JPH1144577A - Infrared sensor and optical sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make compatible both a large light-detection amount and a small light-detection area by constituting a sensor of a condensing element condensing infrared rays radiated from an object to be measured, an infrared-detecting element and a casing, and setting the infrared-detecting element separately from a focal position of the condensing element. SOLUTION: An infrared-detecting element 4 is mounted to a casing 9 in a manner not to detect infrared rays not passing a refraction lens 3 and detect only infrared rays passing the refraction lens 3. An area where the light radiated from a point A does not pass is present at a position further away from the refraction lens 3 than an intersection FX of an optical path K1A and an optical axis and closer to the refraction lens 3 than an image point FA. The area is inside a triangle of the intersection FX, the image point FA and an image point FA'. The infrared-detecting element 4 is arranged inside the triangle, whereby an infrared sensor not detecting the light radiated from the points A, A' located at a boundary is obtained. Only infrared rays radiated from a required area in the vicinity of the optical axis are accordingly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor and an optical sensor.

[0002]

2. Description of the Related Art Conventionally, an infrared sensor that detects infrared rays using an infrared light receiving element has been used. Less than,
An example of the above-described conventional infrared sensor will be described with reference to the drawings.

FIG. 45 shows the structure of a first conventional infrared sensor. In FIG. 45, 9 is a housing, 4 is an infrared sensor, and 10 is an opening.

The operation of the infrared sensor configured as described above will be described below.

[0005] First, the opening 10 is directed to the object to be measured. Infrared rays emitted from the object to be measured pass through the opening of the housing and enter the infrared light receiving element. Taking advantage of the fact that the output of the infrared light receiving element depends on the intensity of the infrared light incident on the infrared light receiving element and the intensity of the infrared light incident on the infrared light receiving element depends on the temperature of the measured object, Is detected, and the presence or absence of an object to be measured is determined. The size of the light receiving area of the infrared sensor is geometrically determined by the size of the infrared light receiving element 4 and the diameter of the opening 4. By reducing the opening diameter of the light receiving section 4 and the opening 10, the light receiving area of the infrared sensor can be reduced.

FIG. 46 shows the configuration of a second conventional infrared sensor. In FIG. 46, 9 is a housing, 4
Denotes an infrared sensor, 10 denotes an opening, and 1 denotes a cylindrical fixing portion for fixing the infrared sensor to a concave portion such as a hole.

The operation of the infrared sensor configured as described above will be described below.

First, the infrared sensor is fixed by inserting the fixing portion 1 into a concave portion such as a hole. Infrared rays emitted from the object to be measured pass through the opening of the fixed part and enter the infrared light receiving element. Taking advantage of the fact that the output of the infrared light receiving element depends on the intensity of the infrared light incident on the infrared light receiving element and the intensity of the infrared light incident on the infrared light receiving element depends on the temperature of the object, Is detected, and the presence or absence of an object to be measured is determined. The size of the light receiving area of the infrared sensor is geometrically determined by the size of the infrared light receiving element 4 and the diameter of the opening 4.

The light receiving area of the infrared sensor can be reduced by reducing the opening diameter of the light receiving section 4 and the opening 10.

[0010]

However, in the configuration shown in the first conventional example, when measuring only a narrow area,
It is necessary to narrow the light receiving area by reducing the size of the opening 10 or the light receiving element 4. Opening 1
0, if the light receiving element 4 is made smaller, the light receiving area becomes smaller, but there is a problem that the light receiving amount becomes smaller. When the amount of received light is small, the S / N of the output of the light receiving element is deteriorated, and the measurement accuracy is reduced.

Further, in the configuration shown in the second conventional example, when the fixed portion is inserted into the object to be measured, the temperature of the fixed portion changes due to the object to be measured, and the amount of infrared rays emitted from the fixed portion changes. In order not to receive the light from the fixed portion, it is necessary to reduce the light receiving area. Therefore, the light receiving area can be reduced by reducing the size of the opening 10 and the light receiving element 4, but there is a problem that the amount of received light also decreases. When the amount of received light is small, the S / N of the output of the light receiving element is deteriorated, and the measurement accuracy is reduced.

In view of the above problems, an object of the present invention is to provide an infrared sensor that achieves both a large light receiving amount and a small light receiving area.

[0013]

In order to achieve the above object, a first infrared sensor according to the present invention comprises at least a light-collecting element for collecting infrared rays radiated from an object to be measured; An infrared light receiving element for receiving infrared light collected by the element,
The light receiving area is limited by including the light-collecting element and a housing for holding the infrared light-receiving element, and disposing the infrared light-receiving element away from the focal position of the light-collecting element.
Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. In addition, by installing the light receiving element away from the focal point of the light collecting element, light incident on the light collecting element from an unnecessary area can travel to a position other than the light receiving element, thereby limiting the light receiving area. Can be.

In the above-mentioned infrared sensor, the infrared light receiving element may be arranged such that the light receiving element is on the same side as a point located on the boundary with respect to the optical axis from a point located on the boundary of the light receiving area on the surface of the object to be measured. A point farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element through the edge of the light-collecting element and located at the boundary by the light-collecting element It is desirable that the light-emitting element be located in a region closer to the light-collecting element than the image point. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

Further, in the above-mentioned infrared sensor, the infrared light receiving element passes through the edge of the light-collecting element on the same side as the point located at the boundary with respect to the optical axis from the point located at the boundary. The triangle formed by the intersection of the optical axis and the optical path reaching the image point of the point located at the boundary by the light-collecting element and the two image points of the point located at the boundary by the light-collecting element It is desirable to install in With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

In the infrared sensor, the infrared light receiving element is located in a region farther from the light condensing element than an image point of the light condensing element at a point located on a boundary of the light receiving region on the object surface. It is desirable to do. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

Further, in the infrared sensor, the infrared light receiving element is passed through an edge of the light collecting element opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary. It is preferable that the light-collecting element be installed in a region sandwiched between two optical paths reaching an image point of a point located at the boundary by the light-collecting element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

In order to achieve the above object, a second infrared sensor according to the present invention comprises a light-collecting element for condensing at least infrared light radiated from an object to be measured, and a light-condensing element. An infrared light receiving element for receiving the infrared light, a housing for holding the light condensing element and the infrared light receiving element, and a fixing portion for fixing a direction to an object to be measured. The light receiving area is limited by installing the element away from the position of the light collecting element. Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. In addition, by installing the light receiving element away from the focal point of the light collecting element, light incident on the light collecting element from an unnecessary area can travel to a position other than the light receiving element, thereby limiting the light receiving area. Can be.

In the above-mentioned infrared sensor, the infrared light receiving element may be arranged such that the light receiving element is located on the same side as a point located on the boundary with respect to the optical axis from a point located on the boundary of the light receiving area on the object surface. It is farther from the light-collecting element than the intersection of the optical path and the optical axis that passes through the edge of the element and reaches the image point of the point located at the boundary by the light-collecting element and is located at the boundary by the light-collecting element. It is desirable that the light source be installed in a region closer to the light-collecting element than the point image point. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

In the infrared sensor, the infrared light receiving element may be moved from a point located at the boundary through an edge of the light collecting element on the same side as a point located at the boundary with respect to an optical axis. Within the triangle formed by the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element, and two image points of the point located at the boundary by the light-collecting element It is desirable to install. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

In the infrared sensor, the infrared light receiving element is located in a region farther from the light condensing element than an image point of the light condensing element at a point located on a boundary of the light receiving region on the object surface. It is desirable to set up.
Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

In the above-mentioned infrared sensor, the infrared light receiving element is passed through an edge of the light collecting element opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary. It is preferable that the light-collecting element be installed in a region sandwiched between two optical paths reaching an image point of a point located at the boundary by the light-collecting element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

In the above-mentioned infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the light collecting element with respect to the optical axis from the edge of the light collecting element. From the point where the straight line intersects the surface of the tip of the fixed part,
The point passing through the edge of the light-collecting element and intersecting with the surface of the tip of the fixed portion is farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point by the light-collecting element, and It is preferable that the light-receiving element be located in a region closer to the light-collecting element than an image point of the light-collecting element at a point crossing the front end surface of the fixed portion. Since a region other than the fixed portion can be used as a light receiving region, a highly accurate infrared sensor which is not affected by a temperature change of the fixed portion can be realized. Further, since the light receiving area can be maximized under the condition that the light receiving area does not receive the light from the fixed portion, S
/ N is improved, and the detection accuracy can be increased.

In the above-mentioned infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the light collecting element with respect to the optical axis from the edge of the light collecting element. An optical path that passes through the edge of the light-collecting element from a point where the straight line intersects the front end surface of the fixed portion to reach two image points of the light converging element at a point where the straight line intersects the front end surface of the fixed portion; Is desirably installed inside a triangle formed by a point intersecting with the optical axis and two image points of the light condensing element at a point intersecting with the surface of the fixed end. Infrared rays from the fixed part can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

In the above-mentioned infrared sensor, the infrared light receiving element may be arranged such that a focal length f of the light collecting element, a radius rs of the infrared light receiving element, and an optical axis from an edge of the light collecting element. The distance rα between the optical axis and a point where a straight line drawn so as to contact the inner wall of the fixed part on the same side as the edge of the light-collecting element, and the light from the edge of the light-collecting element A distance Lα between a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element with respect to an axis and a surface of the tip of the fixed part intersects the light-collecting element; Using the radius r3 of the light collecting element,

[0026]

(Equation 5)

It is desirable that the light source is located farther from the light-collecting element than the focal point of the light-collecting element by L3 given by: Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

In the infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the light collecting element with respect to the optical axis from the edge of the light collecting element. It is desirable to set the point at which the straight line intersects with the surface of the tip of the fixed portion at a position farther from the light-collecting element than an image point by the light-collecting element. Since a region other than the fixed portion can be used as a light receiving region, a highly accurate infrared sensor which is not affected by a temperature change of the fixed portion can be realized. Further, since the light receiving amount can be maximized in the light receiving area under the condition that the light from the fixed portion is not received, the S / N is improved and the detection accuracy can be improved.

In the above-mentioned infrared sensor, the infrared light receiving element may be connected to two points intersecting the front end surface of the fixed portion with respective points intersecting the front end surface of the fixed portion across the optical axis. It is desirable that the light-receiving element be installed in a region between two optical paths that reach an image point of the light-collecting element at two points passing through the edge of the light-collecting element on the opposite side and intersecting the surface of the front end of the fixed part. . Infrared rays from the fixed part can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

In the above-mentioned infrared sensor, the infrared light receiving element may be arranged such that a focal length f of the light collecting element, a radius rs of the infrared light receiving element, and an optical axis from an edge of the light collecting element. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element, and from the edge of the light-collecting element A distance Lα between a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element with respect to the optical axis intersects the surface of the tip of the fixed part and the light-collecting element; Using the radius r3 of the light collecting element,

[0031]

(Equation 6)

It is desirable that the light-receiving element is disposed farther from the light-collecting element than the focal point of the light-collecting element by L3 represented by the following formula. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

In order to achieve the above object, a third infrared sensor according to the present invention comprises a light-collecting element for condensing at least infrared light radiated from an object to be measured, and a light-condensing element. An infrared light receiving element for receiving the infrared light, a housing for holding the light collecting element and the infrared light receiving element, a fixing portion for fixing a direction to the device under test, and an effective area of the light collecting element And a lens aperture stop for limiting the light receiving area, and the light receiving area is limited by installing the infrared light receiving element away from the focal point of the light collecting element. Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. In addition, by installing the light receiving element away from the focal point of the light collecting element, light incident on the light collecting element from an unnecessary area can travel to a position other than the light receiving element, thereby limiting the light receiving area. Can be.

In the infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. An optical path from a point where the straight line intersects the surface of the front end of the fixed portion, passes through the edge of the lens aperture stop, and reaches an image point of the light condensing element at a point where the straight line intersects the surface of the front end of the fixed portion. It is preferable that the light-emitting device be located in a region farther from the light-collecting element than the intersection of the light-collecting element with the optical axis and closer to the light-collecting element than an image point of the light-collecting element at a point that intersects with the front end surface of the fixed portion. . Light incident on the light-collecting element from an unnecessary area can be advanced to a position other than the light-receiving element,
The light receiving area can be limited.

In the infrared sensor, the infrared light receiving element may be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. From the point where the drawn straight line intersects the front end surface of the fixed portion, passes through the edge of the lens aperture stop, and reaches the image point of the light condensing element at the cross point with the front end surface of the fixed portion. It is desirable that the light source is installed inside a triangle formed by an intersection of an optical path and an optical axis and two image points formed by the light-collecting element at a point of intersection with the surface of the tip of the fixed portion.
An optical path and an optical axis that pass through the edge of the lens aperture stop on the same side as the tip of the fixed portion with respect to the optical axis from the tip of the fixed portion and reach the image point at the tip of the fixed portion by the light-collecting element; The light receiving element at a position far from the optical axis even if the light receiving element is located farther from the light condensing element than the intersection with the light condensing element and closer to the light condensing element than the image point of the tip of the fixed part by the light condensing element If it is installed, it will receive infrared rays from the fixed part.
This infrared ray can be prevented from being received.

In the above-mentioned infrared sensor, the infrared light receiving element may be arranged such that a focal length f of the light condensing element, a radius rs of the infrared light receiving element, and an optical axis from an edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the lens aperture stop, and the light from the edge of the lens aperture stop A distance Lα between a point where a straight line drawn so as to be in contact with an inner wall of the fixed portion on the same side as an edge of the lens aperture stop with respect to an axis and a surface of a front end of the fixed portion and the lens aperture stop; Using the distance L2 between the lens aperture stop and the condenser element and the aperture radius r2 of the lens aperture stop,

[0037]

(Equation 7)

The lens is located farther from the light-collecting element than the focal point of the light-collecting element by L3 represented by the following formula, and is located on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part intersects the surface of the tip of the fixed part, the distance rB between a point other than the tip of the fixed part and the optical axis, the light condensing The relationship of rB ≧ rαf (f + L3)> L3 · L2 to the focal length f of the element, the distance L2 between the condenser element and the lens aperture stop, and the distance L3 between the focal point of the condenser element and the infrared receiving element. It is desirable that the following holds. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

In the above-mentioned infrared sensor, the infrared light receiving element is arranged so as to be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. It is desirable that the light source be installed in a region farther from the light-collecting element than an image point of the light-collecting element at a point where a straight line intersects the surface of the tip of the fixed part. Light incident on the light-collecting element from an unnecessary area can be advanced to a position other than the light-receiving element, and the light-receiving area can be limited.

In the infrared sensor, the infrared light receiving element may be located at two points crossing the front end surface of the fixed portion and opposite to the cross points of the front end surface of the fixed portion across the optical axis. It is preferable that the light source is disposed in a region between two optical paths reaching an image point formed by the light-collecting elements at two points passing through the edge of the lens aperture stop on the side and crossing the front end surface of the fixed portion. Infrared rays from the fixed part can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

The radius rs of the infrared light receiving element and a straight line drawn from the edge of the lens aperture stop so as to be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis. The distance rα between the optical axis and a point intersecting with the surface of the front end of the fixed portion, so that the edge of the lens aperture stop is in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis. The distance Lα between the point where the drawn straight line intersects the surface of the fixed part tip and the lens aperture stop, the distance L2 between the lens aperture stop and the condenser element, and the aperture radius r2 of the lens aperture stop are used. hand,

[0042]

(Equation 8)

The lens is located farther from the light-collecting element than the focal point of the light-collecting element by L3, and is located on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part intersects the surface of the tip of the fixed part, the distance rB between a point other than the tip of the fixed part and the optical axis, The relationship of rB ≧ rαf (f + L3)> L3 · L2 to the focal length f of the element, the distance L2 between the condenser element and the lens aperture stop, and the distance L3 between the focal point of the condenser element and the infrared receiving element. It is desirable that the following holds. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

As the light collecting element of the infrared sensor, it is preferable to use a refraction lens, a transmission type diffraction lens, a light collection mirror or a reflection type diffraction lens.

In order to achieve the above object, an optical sensor according to the present invention comprises at least a condensing element for condensing light emitted or reflected from an object to be measured, and a light condensing element for condensing the light condensed by the condensing element. The light receiving element includes a light receiving element that receives light, a light-receiving element, and a housing that holds the light-receiving element. The light-receiving area is limited by installing the light-receiving element away from the focal position of the light-collecting element. Since light emitted or reflected from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. In addition, by installing the light receiving element away from the focal point of the light collecting element, light incident on the light collecting element from an unnecessary area can travel to a position other than the light receiving element, thereby limiting the light receiving area. Can be.

In the above-described optical sensor, the light receiving element may be formed by connecting an edge of the light collecting element on a same side as a point located on the boundary with respect to an optical axis from a point located on the boundary of the light receiving region on the surface of the measured object. An image point of a point that is farther from the light-collecting element than an intersection of an optical path and an optical axis that passes through the light-collecting element and reaches the image point of the point located at the boundary, and that is located at the boundary by the light-collecting element It is desirable to install the light source in a region closer to the light-collecting element. Light from an unnecessary area can be focused on a point other than the light receiving element, and the light receiving area can be limited.

In the above-mentioned optical sensor, the light receiving element is moved from a point located at the boundary to an edge of the light-collecting element on the same side of the optical axis as a point located at the boundary. It is installed in a triangle formed by an intersection of an optical path reaching an image point of a point located at the boundary by an optical element and an optical axis, and two image points of a point located at the boundary by the light-collecting element. It is desirable. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

In the above optical sensor, the light receiving element may be installed in a region farther from the light condensing element than an image point by the light condensing element at a point located on a boundary of the light receiving area on the surface of the object to be measured. desirable. Light from an unnecessary area can be focused on a point other than the light receiving element, and the light receiving area can be limited.

In the above-mentioned optical sensor, the light-receiving element passes the light-collecting element through an edge of the light-collecting element opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary. It is desirable that the device be installed in a region between two optical paths reaching an image point of a point located at the boundary by the element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0050]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an infrared sensor according to a first embodiment of the present invention. In FIG. 1, 3 is a refraction lens, 4 is an infrared light receiving element, 9 is a housing, A and A 'are points located at the boundary between a region to receive light and a region to not receive light, B
Is the point in the area where you do not want to receive light, F is the focal point of the refractive lens, F
A is the image point of A by the refraction lens 3, and FA 'is the refraction lens 3.
A 'is the image point of A', FB is the image point of B by the refracting lens 3, K1A is the light traveling from A to the FA through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis (marginal). K2A is the optical path of light traveling parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is the optical path of light passing from A through the center of the refractive lens 3 and reaching FA. ,
K4A is the optical path of the light (marginal ray) that passes through the edge of the opening of the lens aperture stop 2 opposite to the optical axis from A and reaches FA, and K1A 'is the same side as A' from the optical axis with respect to the optical axis. K2A 'is an optical path of light (marginal ray) that passes through the edge of the aperture of the lens aperture stop 2 and travels to FA'. The light travels from A 'in parallel with the optical axis and passes through the focal point F to reach FA'. K3A 'passes through the center of the refraction lens 3 from A' to F3
K4A 'is an optical path of light reaching A', K3B is an optical path of light (marginal ray) passing through the edge of the opening of lens aperture stop 2 on the opposite side of A from the optical axis and reaching FA '. An optical path of light from B passing through the center of the refractive lens 3 and reaching FB;
FX is the intersection of optical path K1A and optical path K1A '.

An optical system is designed so that only infrared rays radiated from the region to be measured are received by the infrared light receiving element.

The infrared light receiving element 4 is attached to the housing 9 so that infrared light that does not pass through the refractive lens 3 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 1, the light passing through the optical path K2A passes through the refraction lens 3, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, light passing through the optical path K1A passes through the refraction lens 3, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the refraction lens 3, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches the FA without crossing the optical axis. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the point FX where the optical path K1A intersects the optical axis and closer to the refraction lens 3 than FA.
This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

Since the point B outside the region where light is to be received and in the region where light reception is not desired is farther from the optical axis than A, the image point FB of B by the refracting lens 3 may be farther from the optical axis than FA. As is well known. Therefore, FX, FA and FA '
By disposing the infrared light receiving element inside the triangle formed by the light receiving element so as not to receive the infrared light radiated from A and A ′, the infrared light from B is not automatically received.

As described above, by installing the infrared light receiving element 4 inside the triangle formed by FX, FA, and FA ', it is possible to receive only the infrared light radiated from the light receiving area near the optical axis. An infrared sensor is obtained.

FIG. 2 shows an infrared sensor according to a second embodiment of the present invention. In FIG. 2, 3 is a refractive lens, 4 is an infrared light receiving element, 9 is a housing, A and A 'are points located at the boundary between a region where light reception is desired and a region where light reception is not desired, B
Is the point in the area where you do not want to receive light, F is the focal point of the refractive lens, F
A is the image point of A by the refraction lens 3, and FA 'is the refraction lens 3.
A 'is the image point of A', FB is the image point of B by the refracting lens 3, K1A is the light traveling from A to the FA through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis (marginal). K2A is the optical path of light traveling parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is the optical path of light passing from A through the center of the refractive lens 3 and reaching FA. ,
K4A is the optical path of the light (marginal ray) that passes through the edge of the opening of the lens aperture stop 2 opposite to the optical axis from A and reaches FA, and K1A 'is the same side as A' from the optical axis with respect to the optical axis. K2A 'is an optical path of light (marginal ray) that passes through the edge of the aperture of the lens aperture stop 2 and travels to FA'. The light travels from A 'in parallel with the optical axis and passes through the focal point F to reach FA'. K3A 'passes through the center of the refraction lens 3 from A' to F3
K4A 'is an optical path of light reaching A', K3B is an optical path of light (marginal ray) passing through the edge of the opening of lens aperture stop 2 on the opposite side of A from the optical axis and reaching FA '. An optical path of light from B passing through the center of the refractive lens 3 and reaching FB;
FX is the intersection of the optical paths K1A and K1A ', and FY is the intersection of the optical paths K4A and K4A'.

An optical system is designed so that only infrared rays radiated from the area to be measured are received by the infrared light receiving element.

The infrared light receiving element 4 is attached to the housing 9 so that infrared light not passing through the refractive lens 3 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 2, the light passing through the optical path K2A passes through the refracting lens 3 and intersects the optical axis at F at FA.
And moves away from the optical axis. Similarly, the light passing through the optical path K1A passes through the refractive lens 3 and intersects the optical axis, and
And moves away from the optical axis. The light passing through the optical path K3A crosses the optical axis by the refraction lens 3, reaches FA, and moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refracting lens 3, and after passing through the refracting lens 3, reaches the FA without crossing the optical axis, and thereafter approaches or moves away from the optical axis. Go. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the image point FA of A. This area includes the optical path K4A at a portion farther from the refraction lens 3 than FA and the refraction lens 3
This is a region interposed between the optical paths K4A 'at a portion far from the optical path. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

It is well known that B in the region outside the region where light is to be received and not desired to be received is farther from the optical axis than A, so that the image point FB of B by the refracting lens 3 is farther from the optical axis than FA. It is on the street. Therefore, the optical path K4A at a portion farther from the refracting lens 3 than FA and the refracting lens 3 than FA '.
If the infrared ray radiated from A and A 'is prevented from being received by installing the infrared ray detector in the area between the optical paths K4A' far from the The configuration does not receive light.

As described above, the infrared light receiving element 4 is installed in a region between the optical path K4A farther from the refractive lens 3 than FA and the optical path K4A 'farther from the refractive lens 3 than FA'. By doing so, it is possible to obtain an infrared sensor that receives only infrared rays radiated from a region near the optical axis that is desired to be received.

FIG. 3 shows an infrared sensor according to a third embodiment of the present invention. In FIG. 3, reference numeral 3 denotes a refraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, and A and A '. Is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the refractive lens, FA is an image point of A by the refractive lens 3, and FA 'is a refractive lens. 3, the image point of A ′,
FB is an image point of B by the refraction lens 3, K1A is an optical path of light (marginal ray) which travels to A through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A.
Is the optical path of light traveling parallel to the optical axis from A and passing through the focal point F to reach FA; K3A is the optical path of light passing from A through the center of the refractive lens 3 to reach FA; K1A 'is the optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the opposite side with respect to the axis and reaching FA, and K1A' is the lens aperture stop 2 on the same side from A 'with respect to the optical axis. Light that travels to FA 'through the edge of the opening (marginal ray)
K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' reaches FA 'from A' through the center of the refractive lens 3 Light path of light
K4A 'is a lens aperture stop 2 on the opposite side of A from the optical axis.
K3B is an optical path of light (marginal ray) that passes through the edge of the opening and reaches FA ', K3B is an optical path of light passing from B through the center of the refractive lens 3 to FB, and FX is an optical path K1A and an optical path K.
It is the intersection of 1A '.

An optical system is designed such that only infrared rays radiated from a region to be measured near the optical axis are received by the infrared light receiving element.

The infrared light receiving element 4 is attached to the housing 9 so that only the infrared light passing through the refractive lens 3 is received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

The light radiated from A is divided into optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 3, light passing through the optical path K2A passes through the refracting lens 3, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, light passing through the optical path K1A passes through the refraction lens 3, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the refraction lens 3, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches the FA without crossing the optical axis. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the point FX where the optical path K1A intersects the optical axis and closer to the refraction lens 3 than FA.
This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The fixed section 1 is installed so as to be farther from the optical axis than the optical paths K1A and K1A '.

The infrared rays radiated from the fixed portion 1 are replaced with the light radiated from the area on the same surface as the area on which light is not desired to be received. Since point B in the area not to receive light outside the area to receive light is farther from the optical axis than A,
It is well known that the image point FB of B by the refracting lens 3 is farther from the optical axis than FA. Therefore, if an infrared light receiving element is installed inside the triangle formed by FX, FA and FA 'so as not to receive the infrared light radiated from A and A', the infrared light from B is automatically received. No configuration. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light receiving element 4 is installed inside the triangle formed by FX, FA, and FA ', and the optical path K1A,
By providing the fixing portion 1 farther from the optical axis than K1A ', the infrared sensor can be fixed and directed to an area where light reception is desired in a concave portion such as the inside of a hole, and infrared rays emitted from the fixing portion are received. An infrared sensor that receives only infrared rays radiated from an area to be received near the optical axis without receiving the light is obtained.

The housing 9 and the fixing part 1 may be integrated.

FIG. 4 shows an infrared sensor according to a fourth embodiment of the present invention. In FIG. 4, reference numeral 3 denotes a refraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and pointing the infrared sensor to a region to receive light in a concave portion such as the inside of a hole, and A and A ′. Is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the refractive lens, FA is an image point of A by the refractive lens 3, and FA 'is a refractive lens. 3, the image point of A ′,
FB is an image point of B by the refraction lens 3, K1A is an optical path of light (marginal ray) which travels to A through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A.
Is the optical path of light traveling parallel to the optical axis from A and passing through the focal point F to reach FA; K3A is the optical path of light passing from A through the center of the refractive lens 3 to reach FA; K1A 'is the optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the opposite side with respect to the axis and reaching FA, and K1A' is the lens aperture stop 2 on the same side from A 'with respect to the optical axis. Light that travels to FA 'through the edge of the opening (marginal ray)
K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' reaches FA 'from A' through the center of the refractive lens 3 Light path of light
K4A 'is a lens aperture stop 2 on the opposite side of A from the optical axis.
K3B is an optical path of light (marginal ray) that passes through the edge of the opening and reaches FA ', K3B is an optical path of light passing from B through the center of the refractive lens 3 to FB, and FX is an optical path K1A and an optical path K.
It is the intersection of 1A '.

An optical system is designed such that only infrared rays radiated from a region to be measured near the optical axis are received by the infrared light receiving element.

The infrared light receiving element 4 is arranged such that only the infrared light passing through the refractive lens 3 is received by the infrared light receiving element 4.
Attach to The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 4, light passing through the optical path K2A passes through the refracting lens 3 and intersects the optical axis at F at FA.
And moves away from the optical axis. Similarly, the light passing through the optical path K1A passes through the refractive lens 3 and intersects the optical axis, and
And moves away from the optical axis. The light passing through the optical path K3A crosses the optical axis by the refraction lens 3, reaches FA, and moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refracting lens 3, and after passing through the refracting lens 3, reaches the FA without crossing the optical axis, and thereafter approaches or moves away from the optical axis. Go. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the image point FA of A. This area includes the optical path K4A at a portion farther from the refraction lens 3 than FA and the refraction lens 3
This is a region interposed between the optical paths K4A 'at a portion far from the optical path. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

The fixed part 1 is installed so as to be farther from the optical axis than the optical paths K1A and K1A '.

The infrared rays radiated from the fixed part 1 are replaced with the light radiated from the area where it is not desired to receive light. It is well known in geometrical optics that point B in the area outside the area where light is not desired to be received is farther from the optical axis than A, so that image point FB of B by refracting lens 3 is farther from the optical axis than FA. It is on the street. Therefore, by installing the infrared light receiving elements in a region between the optical path K4A farther from the refracting lens 3 than FA and the optical path K4A 'farther from the refracting lens 3 than FA', A and A ' By not receiving the infrared rays radiated from B, the configuration is such that the infrared rays radiated from B are not automatically received. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light receiving element 4 is installed in a region sandwiched between the optical path K4A farther from the refractive lens 3 than FA and the optical path K4A 'farther from the refractive lens 3 than FA'. Then, the fixed portion 1 is moved between the A and the refractive lens 3 by an optical path K.
By providing the infrared sensor farther from the optical axis than 1A and K1A ', the infrared sensor can be stably directed to the area where light is to be received, such as the inside of a hole, in a concave portion, without receiving infrared light radiated from the fixed part. Thus, an infrared sensor that receives only infrared rays radiated from a region desired to be received near the optical axis can be obtained.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIG. 5 shows an infrared sensor according to a fifth embodiment of the present invention. In FIG. 5, reference numeral 3 denotes a refraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to a light receiving region such as the inside of a hole in a concave portion, and α and α ′. Is a point where a straight line contacting the edge of the refractive lens 3 and the inner surface of the fixed part 1 on the same side with respect to the optical axis intersects the front end face of the fixed part, F is the focal point of the refractive lens 3, F
α and Fα ′ are image points of α and α ′ by the refraction lens 3, respectively, and K1 α is the refraction lens 3 on the same side of the optical axis from α.
K2α is the optical path of the light that travels in parallel to the optical axis from α and passes through the focal point F to reach Fα, and K3α is the refraction from α. K4α, the optical path of the light passing through the center of the lens 3 and reaching Fα
K1 is an optical path of light (marginal ray) passing through the edge of the refraction lens 3 on the opposite side of the optical axis and reaching Fα from α.
α ′ is an optical path of light (marginal ray) that travels from α ′ to Fα ′ through the edge of the refraction lens 3 on the same side with respect to the optical axis, and K 2 α ′ travels from α ′ in parallel with the optical axis. K3α 'is the optical path of the light that reaches Fα' after passing through the focal point F, K3α 'is the optical path of the light that reaches Fα' through the center of the refractive lens 3 from α ', and K4α' is the optical axis from α '. FX is the optical path of light (marginal ray) passing through the edge of the refracting lens 3 on the opposite side and reaching Fα ', and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

The infrared light receiving element 4 is attached to the housing 9 so that only the infrared light passing through the refractive lens 3 is received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

In order to receive only the infrared light from the object to be measured, the infrared light radiated from the fixed portion 1 may be prevented from being received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the light passes through the edge of the refractive lens 3 on the same side as the point located at the virtual boundary with respect to the optical axis. What is necessary is just to install the fixing | fixed part 1 so that it may be located far from an optical axis rather than the optical path of light (marginal ray). Therefore, the point located on the virtual boundary is
A point α at which a straight line contacting from the edge of the refracting lens 3 to the inner surface of the fixed portion 1 on the same side with respect to the edge and the optical axis intersects the fixed portion tip surface;
As α ′, the infrared light receiving element 4 is installed inside a triangle formed by Fα, Fα ′ and FX. As a result, the fixed unit 1 is located farther from the optical axis than the optical paths K1α and K1α 'between α and the refracting lens 3, so that an optical system that does not receive light from the fixed unit is obtained.

The above is described in detail below. The light emitted from α reaches the image point Fα of α through the optical paths K1α, K2α, K3α, K4α, and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 5, light passing through the optical path K2.alpha. Passes through the refracting lens 3, crosses the optical axis at F, and reaches F.alpha. Similarly, the light passing through the optical path K1α passes through the refractive lens 3, crosses the optical axis, and reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the refraction lens 3 and then reaches Fα while leaving the optical axis. Light passing through the optical path K4α crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches Fα without crossing the optical axis. As described above, there is an area where light emitted from α does not pass at a position farther from the refraction lens than the point FX where the optical path K1α intersects the optical axis and closer to the refraction lens 3 than Fα. Similarly, α ′ is located at a position farther from the refraction lens than the point where the optical path intersects with the optical path K1α ′ and F
At a position closer to the refractive lens 3 than α ′, there is a region through which light emitted from α ′ does not pass. This Fα, F
By installing the infrared light receiving element 4 inside the triangle formed by α 'and FX, an infrared sensor that does not receive light emitted from α and α' can be obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the refractive lens 3 is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. The intersection of this point with the refractive lens 3 is Fα
It is well known in geometrical optics that it is farther from the optical axis than it is. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received, and therefore no light from the fixed portion 1 will be received. Similarly, light from a portion farther from the optical axis than the optical path K1 α 'between α' and the refractive lens 3 is replaced with light from a point whose distance from the optical axis is larger than α 'in the same plane as α'. Can be It is well known in geometrical optics that the intersection of this point with the refraction lens 3 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, light from a point farther from the optical axis than α ′ will not be received, and therefore no light from the fixed portion 1 will be received. As described above, by disposing the infrared light receiving element 4 inside the triangle formed by Fα, Fα ′ and FX so as not to receive the infrared rays radiated from α and α ′, the fixing part is automatically set. The configuration is such that infrared rays radiated from 1 are not received.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is a refracting lens 3 more than FA.
Close to. At this time, equations (1) and (2) hold.

Lα ≧ f + L3 (1) ∴L3 ≦ Lα−f (2) As shown in FIG. 5, the light receiving surface is located between the point where the optical axis intersects the optical path K1α with the optical axis and Fα. Of the light paths closest to the infrared light receiving element 4 on the light receiving surface is K1α.
It is. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (3).

Rαs1> rs (3) rαS where r3, rαF, r
αS1, L3, and f satisfy Equations (4) and (5) as geometric relationships.

[0088]

(Equation 9)

By substituting equation (5) into equation (3), equation (6) is obtained.

[0090]

(Equation 10)

From the expressions (2) and (6), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is the expression (7).

[0092]

[Equation 11]

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by the following equation (8) as a geometric relationship.
Equation (9) is satisfied.

[0094]

(Equation 12)

By substituting the expression (9) into the expression (7), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 becomes the expression (10).

[0096]

(Equation 13)

Also, from Gauss's formula, equation (11), (1
2) Formula holds.

[0098]

[Equation 14]

By substituting the expression (12) into the expression (11), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the expression (13).

[0100]

(Equation 15)

As described above, in order for the infrared light receiving element 4 not to receive the light radiated from α at the tip of the fixed portion 1,
It is necessary to design the optical system to satisfy the expression (7), the expression (10), or the expression (13). Equation (7), (1
0) and L3 given by equation (13).
Is shifted from the focal point of the refraction lens 3 so that the infrared light emitted from the object to be measured is received only by the infrared light receiving element 4 without receiving the infrared light emitted from the fixed portion 1 by the infrared light receiving element 4. Therefore, it is possible to prevent a measurement error due to a temperature change of the fixing unit 1.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIG. 6 shows an infrared sensor according to a sixth embodiment of the present invention. In FIG. 6, reference numeral 3 denotes a refractive lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, α and α ′. Is a point where a straight line contacting the edge of the refractive lens 3 and the inner surface of the fixed part 1 on the same side with respect to the optical axis intersects the front end face of the fixed part, F is the focal point of the refractive lens 3, F
α and Fα ′ are image points of α and α ′ by the refraction lens 3, respectively, and K1 α is the refraction lens 3 on the same side of the optical axis from α.
K2α is the optical path of the light that travels in parallel to the optical axis from α and passes through the focal point F to reach Fα, and K3α is the refraction from α. K4α, the optical path of the light passing through the center of the lens 3 and reaching Fα
K1 is an optical path of light (marginal ray) passing through the edge of the refraction lens 3 on the opposite side of the optical axis and reaching Fα from α.
α ′ is an optical path of light (marginal ray) that travels from α ′ to Fα ′ through the edge of the refraction lens 3 on the same side with respect to the optical axis, and K 2 α ′ travels from α ′ in parallel with the optical axis. K3α 'is the optical path of the light that reaches Fα' after passing through the focal point F, K3α 'is the optical path of the light that reaches Fα' through the center of the refractive lens 3 from α ', and K4α' is the optical axis from α '. FX is the optical path of light (marginal ray) passing through the edge of the refracting lens 3 on the opposite side and reaching Fα ', and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

The infrared light receiving element 4 is mounted on the housing 9 so that only the infrared light passing through the refractive lens 3 is received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the refractive lens 3 is received.

In order to receive only the infrared light from the object to be measured, the infrared light radiated from the fixed portion 1 may not be received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the light passes through the edge of the refractive lens 3 on the same side as the point located at the virtual boundary with respect to the optical axis. What is necessary is just to install the fixing | fixed part 1 so that it may be located far from an optical axis rather than the optical path of light (marginal ray). Therefore, the point located on the virtual boundary is
A point α at which a straight line contacting from the edge of the refracting lens 3 to the inner surface of the fixed portion 1 on the same side with respect to the edge and the optical axis intersects the fixed portion tip surface;
As α ', an infrared sensor is installed in a region between the optical path K4α farther from the refracting lens 3 than Fα and the optical path K4α' farther from the refracting lens 3 than Fα '.
As a result, the fixed portion 1 moves the optical path K between α and the refractive lens 3.
Since it is located farther from the optical axis than 1α and K1α ', an optical system that does not receive light from the fixed portion can be obtained.

The details will be described below.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 6, the light passing through the optical path K2α passes through the refraction lens 3, crosses the optical axis at F, reaches Fα, and moves away from the optical axis. Similarly, the light passing through the optical path K1α passes through the refractive lens 3, crosses the optical axis, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 3α crosses the optical axis by the refraction lens 3, reaches Fα, and moves away from the optical axis. The light passing through the optical path K4α crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches Fα without crossing the optical axis and thereafter approaches or moves away from the optical axis. To go. Thus, α
There is a region where light emitted from α does not pass at a position farther from the refraction lens than the image point Fα. Similarly, for α ′, there is a region where light emitted from α does not pass at a position further away from the refraction lens than the α image point Fα. By installing an infrared light receiving element in an area sandwiched between the optical path K4α farther from the refractive lens 3 than Fα and the optical path K4α ′ farther from the refractive lens 3 than Fα ′, α, An infrared sensor that does not receive infrared light emitted from α ′ is obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the refractive lens 3 is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the intersection of this point with the refracting lens 3 is farther from the optical axis than Fα. Therefore, if the light from α is not received,
It does not receive light from a point farther from the optical axis than α, and therefore does not receive light from the fixed part 1. Similarly, light from a portion farther from the optical axis than the optical path K1 α 'between α' and the refractive lens 3 is replaced with light from a point whose distance from the optical axis is larger than α 'in the same plane as α'. Can be It is well known in geometrical optics that the intersection of this point with the refraction lens 3 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, light from a point farther from the optical axis than α ′ will not be received, and therefore no light from the fixed portion 1 will be received.
As described above, the infrared light receiving element 4 is provided in a region between the optical path K4α farther from the refraction lens 3 than Fα and the optical path K4α ′ farther from the refraction lens 3 than Fα ′. If infrared rays emitted from α and α 'are not received, infrared rays emitted from the fixing unit 1 are not automatically received.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is a refracting lens 3 more than Fα.
Far from. At this time, equations (14) and (15) hold.

LαF ≦ f + L3 (14) ∴L3 ≧ LαF−f (15) As shown in FIG. 6, since the light receiving surface is farther from the refracting lens 3 than Fα, the light receiving surface of each light path from α to Fα The one that comes closest to the infrared light receiving element 4 is K4α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (16).

Rαs4> rs (16) Here, as is well known in geometrical optics, r3, rαF, LαF,
rαS4, L3, and f are expressed by the following equation (17) as a geometric relationship.
8) Formula is satisfied.

[0113]

FIG. 16

The expression (19) is obtained by substituting the expression (18) into the expression (16).

[0115]

FIG.

From the equations (15) and (19), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (2)
0).

[0117]

FIG.

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by a geometric relationship (21)
Equation (22) is satisfied.

[0119]

FIG.

By substituting the expression (22) into the expression (20), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the expression (23).

[0121]

FIG.

Also, from Gauss's formula, equation (24), (2
5) Formula holds.

[0123]

FIG. 21

By substituting equation (25) into equation (23), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 is given by equation (26).

[0125]

FIG.

As described above, in order to prevent the light radiated from α from being received by the infrared receiving element 4, the optical system must satisfy the condition of the expression (20), the expression (23) or the expression (26). Need to be designed. Expression (20), Expression (23),
By disposing the light receiving element 4 from the focal point of the refraction lens 3 by L3 given by the equation (26), the infrared light radiated from the fixed part 1 is not received by the infrared light receiving element 4 but is received from the object to be measured. Since only the emitted light can be received by the infrared light receiving element 4, a measurement error caused by a temperature change of the fixed portion 1 can be prevented.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIGS. 7 and 8 show an optical system of an infrared sensor according to a seventh embodiment of the present invention. 7 and 8, 3 is a refractive lens, 4 is an infrared light receiving element, 9 is a housing,
1 is a fixing portion for fixing and pointing the infrared sensor to a region where light is to be received in a concave portion such as the inside of a hole, 2 is a lens aperture stop for determining an effective area of the refraction lens 3, and α and α 'are lens aperture stops. A point at which a straight line contacting from the edge of No. 2 to the inner surface of the fixed portion 1 on the same side with respect to this edge and the optical axis intersects the fixed portion tip end face
A is a point at the tip of the fixed part 1, B is a point other than the tip of the fixed part 1, F
Is the focal point of the refractive lens 3, Fα and Fα ′ are the image points of α and α ′ by the refractive lens 3, FA is the image point of A by the refractive lens 3, FB is the image point of B by the refractive lens 3, and K1
α is an optical path of light (marginal ray) which travels to Fα through the edge of the opening of the lens aperture stop 2 on the same side of the optical axis from α, and K2α travels from α in parallel with the optical axis and focuses. F
K3 α is the optical path of light that reaches Fα through α and passes through the center of the refractive lens 3 from α.
K4 α is a lens aperture stop 2 on the opposite side of the optical axis from α.
K1A passes through the edge of the aperture of the lens aperture stop 2 on the same side of the optical axis from A, and travels to FA through the optical path of the light (marginal ray) that passes through the edge of the aperture and reaches Fα. The optical path of light (marginal ray), K2A, is the optical path of light that travels in parallel with the optical axis from A, passes through the focal point F, and reaches FA.
Is the optical path of the light from A passing through the center of the refracting lens 3 to reach FA, and K4A is the light from A passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis and reaching FA. K1B is the optical path of the (marginal ray), K1B is the optical path of the light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis and traveling to FB, and K2B is the optical axis of B from the optical axis. K3B is the optical path of light that travels in parallel to the focal point F and reaches FB, K3B is the optical path of light that passes from B to the center of the refracting lens 3 and reaches FB, and K4B is the opposite optical axis from B across the optical axis. The optical path of the light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the side and reaching FB, FαS1 is the intersection of the optical path K1α with the light receiving surface, FAS1 is the intersection of the optical path K1A and the light receiving surface,
FBS1 is the intersection between the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the point α, rA is the opening radius of the fixed part 1 at the point A, rB is the opening radius of the fixed part 1 at the point B, r2 is the aperture radius of the lens aperture stop 2, r3 .alpha.1 is the distance of the optical path K1 .alpha. from the optical axis of the refractive lens 3, r3A1 is the distance of the optical path K1A from the optical axis of the refractive lens 3, and r3B1 is the optical path K1B.
, The distance from the optical axis of the refractive lens 3, rs is the radius of the infrared light receiving element 4, rαS1 is the distance between FαS1 and the optical axis, rAS1
Is the distance between FAS1 and the optical axis, rBS1 is the distance between FBS1 and the optical axis, rAF is the distance between FA and the optical axis, rBF is the distance between FB and the optical axis, L α is the distance from α to the lens aperture stop 2. Distance, LA is the distance from A to lens aperture stop 2, LB is the distance from B to lens aperture stop 2, L2 is the distance from lens aperture stop 2 to refraction lens 3, f is the focal length of refraction lens 3, L3 Is the distance from F to the infrared light receiving element 4, LαF is the distance from the refractive lens 3 to Fα, and LAF is the refractive lens 3
LFA is the distance from the refractive lens 3 to FB.

Optical design conditions are determined so that light emitted from any point of the fixed portion is not received by the infrared light receiving element 4. For this purpose, the light radiated from α is imagined, and a design condition for preventing the light from being received by the infrared light receiving element 4 is determined. A condition that light is not received by the element 4 is added.

First, the position of the infrared light receiving element 4 is determined as follows so as not to receive the infrared light radiated from α of the fixed portion 1.

The light radiated from α has optical paths K 1 α, K 2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 7, the light passing through the optical path K2.alpha. Passes through the refracting lens 3, crosses the optical axis at F, and reaches F.alpha. Similarly, the light passing through the optical path K1α passes through the refractive lens 3, crosses the optical axis, and reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the refraction lens 3 and then reaches Fα while leaving the optical axis. Optical path K4
The light passing through α crosses the optical axis, passes through the refractive lens 3, and
After passing through the refractive lens 3, the light reaches Fα without crossing the optical axis. As described above, there is a region where the light emitted from α does not pass at a position farther from the refraction lens than the point where the optical path K1α intersects the optical axis and closer to the refraction lens 3 than Fα. By arranging the infrared light receiving element 4 at a position farther from the refraction lens 3 than at the point where the optical path K1 α intersects the optical axis and closer to the refraction lens 3 than Fα, the light radiated from α is not received. An infrared sensor is obtained.

Hereinafter, L3 is obtained.

The infrared light receiving element 4 is a refracting lens 3 more than Fα.
Close to. At this time, equations (27) and (28) hold.

Lα ≧ f + L3 (27) ∴L3 ≦ Lα−f (28) As shown in FIG. 7, the light receiving surface is located between the point where the optical axis intersects the optical path K1α and the optical axis and Fα. Of the light paths closest to the infrared light receiving element 4 on the light receiving surface is K1α.
It is. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (29).

Rαs1> rs (29) Here, as is well known in geometrical optics, r3α1, rαF, Lα
F, rαS1, L3, and f are expressed by the following equation (30) as a geometric relationship:
Equation (31) is satisfied.

[0136]

(Equation 23)

By substituting equation (31) into equation (29), equation (32) is obtained.

[0138]

(Equation 24)

From the equations (28) and (32), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (3)
3) Equation is obtained.

[0140]

(Equation 25)

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (34)
Equation (35) is satisfied.

[0142]

(Equation 26)

By substituting the equation (35) into the equation (33), the condition for preventing the light radiated from α from being received by the infrared receiving element 4 becomes the equation (36).

[0144]

[Equation 27]

Also, from Gauss's formula, equation (37), (3
8) Equation holds.

[0146]

[Equation 28]

By substituting the equation (38) into the equation (36), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the equation (39).

[0148]

(Equation 29)

As is well known in geometrical optics, r2, r
α, Lα, r3α1 and L2 are expressed as geometric relationships (40)
Equation (41) is satisfied.

[0150]

[Equation 30]

By substituting equation (41) into equation (39), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (42).

[0152]

(Equation 31)

As described above, in order to prevent the light radiated from α at the tip of the fixed portion 1 from being received by the infrared light receiving element 4, (3
It is necessary to design the optical system so as to satisfy the condition of the expression (3), the expression (36), the expression (39), or the expression (42).

An infrared sensor whose optical system is designed so as to satisfy the condition of the expression (33), the expression (36), the expression (39) or the expression (42) emits light from a point other than α of the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, a condition for not receiving light from A and B will be described below with reference to FIG.

First, a condition for not receiving the light radiated from A is determined. As shown in FIG. 8, of the light paths from A to FA, the light path closest to the infrared light receiving element 4 on the light receiving surface is K
1A. In the case of a fixed part shape where A and α do not match, K
1A is shielded from light by the fixed part 1 between A and the lens aperture stop 2, and each optical path does not approach the infrared light receiving element 4 on the light receiving surface more than K1A. Therefore, the condition that the light radiated from A is not received by the infrared light receiving element 4 is that the distance rAS1 between the optical axis and FAS1, which is the intersection of K1A and the light receiving surface, is larger than rs. That is, if the following equation is satisfied, the light radiated from A is not received by the infrared light receiving element 4.

RAS1> rs (43) As is well known in geometrical optics, r3A1, rAF, LA, r
As1, f, and L3 are expressed by the geometrical relation (44) and (45).
Satisfy the formula.

[0157]

(Equation 32)

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (46) as a geometric relationship.
7) Formula is satisfied.

[0159]

[Equation 33]

By substituting equation (47) into equation (45), equation (48) is obtained.

[0161]

(Equation 34)

Also, from Gauss's formula, equation (49), (5
Equation (0) holds.

[0163]

(Equation 35)

By substituting equation (50) into equation (48), equation (51) is obtained.

[0165]

[Equation 36]

As is well known in geometrical optics, r2, rA
, LA, r3A1 and L2 are expressed by the following equation (52) as a geometric relationship.
Formula (53) is satisfied.

[0167]

(37)

By substituting equation (53) into equation (51), equation (54) is obtained.

[0169]

(38)

As in the case of rAS1, rαS1 is given by equation (55).

[0171]

[Equation 39]

A is a point at the tip of the fixed portion, and α is a point where a straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed portion 1 on the same side with respect to the optical axis intersects the tip of the fixed portion. ,
The distances from the lens aperture stop 2 to A and α are equal (5
Equation 6) holds, and the distance from the optical axis to A is α from the optical axis.
(57) holds.

LA = Lα (56) rA ≧ rα (57) By substituting equation (56) into equation (55), equation (58) is obtained.

[0174]

(Equation 40)

Since rαS1 satisfies the relationship of equation (29),
If rAS1 is larger than rαS1, that is, if the following expression (59) is satisfied, rAS1 automatically satisfies the relationship of expression (43).

RAS1> rαS1 (59) By substituting equations (55) and (58) into equation (59), equation (60) is obtained.

(RA−r2) × (f (f + L3) −L3 · L2)> (rα−r2) × (f (f + L3) −L3 · L2) (60) From equation (57), equation (60) Is as shown in equation (61).

F (f + L3)> L3 · L2 (61) As described above, the light radiated from the virtual point α and the tip point A of the fixed part 1 is not received by the infrared light receiving element 4 (33). It is necessary to satisfy the condition of the expression, the expression (36), the expression (39), or the expression (42), and the expression (61).

Next, a condition for not receiving light emitted from B will be determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. Since B is a point other than the tip of the fixed portion, B is closer to the refractive lens 3 than the point α on the tip surface of the fixed portion. Therefore, as is well known in geometrical optics, the image point FB is farther from the refraction lens 3 than the image point Fα of the refraction lens 3. That is, equation (62) holds.

LBF> LαF (62) The distance from the refractive lens 3 to the light receiving surface is smaller than the distance from the refractive lens 3 to Fα. Therefore, according to equation (62), the distance from the refractive lens 3 to the light receiving surface is
Is smaller than the distance from to FB. At this time, as shown in FIG. 8, K1B is the light path closest to the infrared light receiving element 4 on the light receiving surface among the optical paths from B to FB.
In order to prevent the light radiated from B from being received by the infrared light receiving element 4, the distance rBS1 between the optical axis and FBS1, which is the intersection of K1B and the light receiving surface, needs to be larger than rs. That is, (6
3) The equation needs to be satisfied.

RBS1> rs (63) As is well known in geometrical optics, r3B1, rBF, LB, r
Bs1, f, and L3 are expressed by the following equations (64) and (65) as geometric relationships.
Satisfy the formula.

[0182]

[Equation 41]

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (66) as a geometric relationship.
7) Formula is satisfied.

[0184]

(Equation 42)

By substituting equation (67) into equation (65), equation (68) is obtained.

[0186]

[Equation 43]

Also, from Gauss's formula, equation (69), (7
Equation (0) holds.

[0188]

[Equation 44]

By substituting equation (70) into equation (68), equation (71) is obtained.

[0190]

[Equation 45]

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are expressed by the following equation (72) as a geometric relationship.
Formula (73) is satisfied.

[0192]

[Equation 46]

By substituting equation (73) into equation (71), equation (74) is obtained.

[0194]

[Equation 47]

As in the case of rBS1, rαS1 is given by equation (75).

[0196]

[Equation 48]

Since rαS1 satisfies the relationship of equation (29),
If rBS1 is larger than rαS1, that is, if equation (76) is satisfied, rBS1 automatically satisfies the relation of equation (63).

RBS1> rαS1 (76) By substituting equations (74) and (75) into equation (76), equation (77) is obtained.

[0199]

[Equation 49]

Here, since α is a point on the tip end surface of the fixed portion 1, Lα and LB satisfy the relations of equations (78) and (79).

[0201]

[Equation 50]

An infrared sensor that satisfies the condition of the expression (33), the expression (36), the expression (39), or the expression (42), and the optical system designed to satisfy the expression (61), In order not to receive the radiated light from points other than the surface, the relationship of the equation (77) needs to be established for each point B.

Therefore, it is necessary to satisfy the expression (80) by considering the relationship between the expressions (61) and (79).

RB−r2 ≧ rα−r2 (80) ∴rB ≧ rα (81) As described above, in order to prevent the light radiated from the fixed part 1 from being received by the infrared light receiving element 4, the following equation (33) is used. Or (36)
It is necessary to satisfy the condition of the expression, the expression (39), or the expression (42), the expression (61), and the expression (81).

The infrared light receiving element 4 is provided away from the focal plane of the refractive lens 3 by an amount given by the expression (33), (36), (39), or (42).
In addition, by adopting an optical design that satisfies the formulas (61) and (81), the infrared light radiated from the object to be measured is received only by the infrared light , It is possible to prevent a measurement error caused by a temperature change of the fixed portion.

The housing 9, the fixed section 1, and the lens aperture stop 2 may be integrated.

FIGS. 9, 10 and 11 show an optical system of an infrared sensor according to the eighth embodiment of the present invention. FIG.
In 10 and 11, 3 is a refraction lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to an area to receive light in a concave portion such as the inside of a hole, 2
Is a lens aperture stop for determining the effective area of the refraction lens 3, and α and α 'are straight lines contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis. A is the point at the tip of the fixed part 1 and B is the fixed part 1
F is the focal point of the refractive lens 3, Fα, F
α ′ is the image point of α and α ′ by the refracting lens 3, respectively, F
A is the image point of A by the refraction lens 3 and FB is the refraction lens 3
Is the image point of B, K1α is the optical path of light (marginal ray) traveling from α to Fα through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis, and K2α is the light from α. The optical path of light traveling parallel to the axis and passing through the focal point F and reaching Fα, K3α is Fα passing through the center of the refractive lens 3 from α.
K4α is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side from α with respect to the optical axis and reaching Fα, and K1A is an optical path from A. The optical path of light (marginal ray) that passes through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the axis and travels to FA, K2A
Is the optical path of light traveling parallel to the optical axis from A and passing through the focal point F to reach FA; K3A is the optical path of light passing from A through the center of the refractive lens 3 to reach FA; K1B is the optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 opposite to the axis and reaching the FA.
K2B passes through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis and travels to FB (marginal ray). K2B travels from B in parallel with the optical axis and passes through the focal point F. K3B is the optical path of the light that reaches FB from B through the center of the refracting lens 3, and K4B is the optical path of the lens aperture stop 2 opposite the optical axis from B across the optical axis. The optical path of the light (marginal ray) that reaches the FB through the edge,
FαS4 is the intersection of the optical path K4α with the light receiving surface, and FAS4 is the optical path K4
FBS4 is the intersection between the optical path K1B and the light receiving surface, FBS1 is the intersection between the optical path K1A and the light receiving surface, FBS1 is the intersection between the optical path K1B and the sensor surface, and rα is the fixed part 1 at the α point. RA is the opening radius of the fixed part 1 at the point A, rB is the opening radius of the fixed part 1 at the point B, and r2 is the lens aperture stop 2.
R3α4 is the distance of the optical path K4α from the optical axis of the refractive lens 3, r3A4 is the distance of the optical path K4A from the optical axis of the refractive lens 3, r3B4 is the distance of the optical path K4B from the optical axis of the refractive lens 3, r3 α1 is the optical path K1
α is the distance of the refracting lens 3 from the optical axis, r3B1 is the distance of the optical path K1B from the optical axis of the refracting lens 3, rs is the radius of the infrared light receiving element 4, rαS4 is the distance between FαS4 and the optical axis,
rAS4 is the distance between FAS4 and the optical axis, rBS4 is the distance between FBS4 and the optical axis, rαS1 is the distance between FαS1 and the optical axis, and rBS1 is FBS.
The distance between BS1 and the optical axis, rαF is the distance between Fα and the optical axis, r
AF is the distance between FA and the optical axis, rBF is the distance between FB and the optical axis,
L α is the distance from α to the lens aperture stop 2, LA is the distance from A to the lens aperture stop 2, LB is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the refractive lens 3. , F is the focal length of the refractive lens 3, L3
Is the distance from F to the infrared light receiving element 4, LαF is the distance from the refractive lens 3 to Fα, and LAF is the distance from the refractive lens 3 to FA.
, LBF is the distance from the refractive lens 3 to FB.

The infrared light radiated from α on the fixed portion 1 is assumed, and the position of the infrared light receiving element 4 is determined as described below so as not to receive this light.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 9, light passing through the optical path K2.alpha. Passes through the refractive lens 3, crosses the optical axis at F, reaches F.alpha., And leaves the optical axis. Similarly, the light passing through the optical path K1α passes through the refractive lens 3, crosses the optical axis, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 3α crosses the optical axis by the refraction lens 3, reaches Fα, and moves away from the optical axis. The light passing through the optical path K4α crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches Fα without crossing the optical axis and thereafter approaches or moves away from the optical axis. To go. Thus, α
There is a region where light emitted from α does not pass at a position farther from the refraction lens than the image point Fα. By installing the infrared light receiving element 4 at a position farther from the refractive lens 3 than the image point Fα of α, an infrared sensor that does not receive light emitted from α can be obtained. Hereinafter, the distance L3 from the focal point of the refracting lens 3 to the light receiving surface is obtained.

The infrared light receiving element 4 is a refracting lens 3 more than Fα.
Far from. At this time, equations (82) and (83) hold.

LαF ≦ f + L3 (82) ∴L3 ≧ LαF-f (83) As shown in FIG. 9, since the light receiving surface is farther from the refracting lens 3 than Fα, the light receiving surface of each light path from α to Fα The one that comes closest to the infrared light receiving element 4 is K4α. Therefore, in order for the infrared light receiving element 4 not to receive the light from α, it is necessary to satisfy the expression (84).

Rαs4> rs (84) Here, as is well known in geometrical optics, r3α4, rαF, Lα
F, rαS4, L3, and f are expressed by the following equation (85) as a geometric relationship:
Equation (86) is satisfied.

[0213]

(Equation 51)

By substituting equation (86) into equation (84), equation (87) is obtained.

[0215]

(Equation 52)

From the equations (83) and (87), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (8
8)

[0219]

(Equation 53)

Furthermore, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (89)
Equation (90) is satisfied.

[0219]

(Equation 54)

By substituting the expression (90) into the expression (88), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the expression (91).

[0221]

[Equation 55]

Further, from Gauss's formula, equation (92), (9
3) Equation holds.

[0223]

[Equation 56]

By substituting equation (93) into equation (91), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (94).

[0225]

[Equation 57]

As is well known in geometrical optics, r 2, r
α, Lα, r3α4, L2 are expressed as a geometric relationship (95)
Equation (96) is satisfied.

[0227]

[Equation 58]

By substituting the expression (96) into the expression (94), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the expression (97).

[0229]

[Equation 59]

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) It is necessary to design an optical system to satisfy the conditions.

An infrared sensor whose optical system is designed so as to satisfy the condition of the expression (88), the expression (91), the expression (94), or the expression (97) emits light from a point other than α of the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, conditions for not receiving light from A and B will be obtained below with reference to FIGS.

First, the condition for not receiving the light radiated from A is determined according to FIG. Since the distance from A to the refractive lens 3 and the distance from α to the refractive lens 3 are equal, the image point F of A and α by the refractive lens 3 is known as geometrical optics.
A and Fα are formed in the same plane. Therefore, the light receiving surface is F
Since it is farther from the refractive lens 3 than α, the light receiving surface is farther than FA. Therefore, as shown in FIG.
K4A is the light path closest to the infrared light receiving element 4 on the light receiving surface among the optical paths up to A. In order to prevent the light emitted from A from being received by the infrared light receiving element 4, the distance rAS4 between the optical axis and FAS4, which is the intersection of K4A and the light receiving surface, needs to be larger than rs. That is, equation (98) needs to be satisfied.

RAS4> rs (98) As is well known in geometrical optics, r3A4, rAF, LAF, r
As4, f, and L3 are expressed as a geometric relationship in equation (99), equation (100).
Satisfy the formula.

[0234]

[Equation 60]

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (101) as a geometric relationship.
02) is satisfied.

[0236]

[Equation 61]

By substituting equation (102) into equation (100), equation (103) is obtained.

[0238]

(Equation 62)

Also, from Gauss's formula, equation (104)
Equation (105) holds.

[0240]

[Equation 63]

By substituting equation (105) into equation (103), equation (106) is obtained.

[0242]

[Equation 64]

As is well known in geometrical optics, r2, rA
, LA, r3A4, and L2 are expressed as geometric relationships (107)
Equation (108) is satisfied.

[0244]

[Equation 65]

By substituting equation (108) into equation (106), equation (109) is obtained.

[0246]

[Equation 66]

Similar to rAS4, rαS4 is given by equation (110).

[0248]

[Equation 67]

Since rαS4 satisfies the relationship of equation (84),
If equation (111) is satisfied, rAS4 automatically satisfies the relation of equation (98).

R AS4> r α S4 (111) By substituting the expressions (109) and (110) into the expression (111), the expression (112) is obtained.

[0251]

[Equation 68]

A is a point at the tip of the fixed portion, and α is a point where a straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed portion 1 on the same side with respect to this edge and the optical axis intersects the tip of the fixed portion. ,
The distances from the lens aperture stop 2 to A and α are equal (1
Expression 13) holds, and the distance from the optical axis to A is equal to or greater than the distance from the optical axis to α, and Expression (114) holds.

LA = Lα (113) rA ≧ rα (114) From the expression (113), the condition of the expression (112) is as shown in the expression (115).

(R2 + rA) × (f (f + L3) −L3 · L2)> (r2 + rα) × (f (f + L3) −L3 · L2) (115) From the expression (114), the condition of the expression (115) is as follows. 116)
Equation (117) is obtained.

F (f + L3) −L3 · L2> 0 (116) f (f + L3)> L3 · L2 (117) Equation (88), Equation (91), Equation (94), or Equation (97) In order that the infrared sensor designed with the optical constants and each positional relationship so as to satisfy the condition (1) does not receive the radiation light from the fixed portion tip A, the optical design needs to satisfy the condition of the expression (117).

Next, a condition for not receiving light emitted from B is determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. B to FB
The light path closest to the infrared light receiving element 4 on the light receiving surface is K4B when the image point FB is closer to the refraction lens 3 than the light receiving surface, as shown in FIG. When the image point FB is closer to the refraction lens 3 than the light receiving surface, K1B is determined.

First, as shown in FIG. 10, when FB is closer to the refraction lens 3 than the light receiving surface, and K4B is closest to the infrared light receiving element 4 in the light receiving surface among the optical paths from B to FB. The following shows a condition in which light emitted from B is not received by the infrared light receiving element 4.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, it is necessary to use the FBS4 at the intersection of K4B and the light receiving surface.
The distance rBS4 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (118) needs to be satisfied.

R BS4> rs (118) As is well known in geometrical optics, r 3B4, rBF, LBF, r
Bs4, f, and L3 are expressed by the following equation (119) as a geometric relationship.
0) is satisfied.

[0260]

[Equation 69]

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (121) as a geometric relationship.
22) Formula is satisfied.

[0262]

[Equation 70]

By substituting equation (122) into equation (120), equation (123) is obtained.

[0264]

[Equation 71]

Also, from Gauss's formula, equation (124)
Equation (125) holds.

[0266]

[Equation 72]

By substituting equation (125) into equation (123), equation (126) is obtained.

[0268]

[Equation 73]

As is well known in geometrical optics, r2, rB
, LB, r3B4, and L2 are expressed as geometric relationships (127)
Equation (128) is satisfied.

[0270]

[Equation 74]

By substituting equation (128) into equation (126), equation (129) is obtained.

[0272]

[Equation 75]

Similarly to rBS4, rαS4 is given by equation (130).

[0274]

[Equation 76]

Since rαS4 satisfies the relationship of equation (84),
If equation (131) is satisfied, rBS4 automatically becomes (118)
This satisfies the relationship of the expression.

R BS4> rα S4 (131) (129) By substituting equation (130) into equation (131), equation (132) is obtained.

[0277]

[Equation 77]

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (133) and (134) hold for Lα and LB.

[0279]

[Equation 78]

The condition of the expression (88), the expression (91), the expression (94), or the expression (97) is satisfied, and (11)
The infrared sensor designed with the optical constants and each positional relationship according to the condition of the expression 7) does not receive the light emitted from any point other than the tip of the fixed part, that is, does not receive the light emitted from any point of the fixed part. To do this, for any B (132)
It is necessary that the relationship of the expressions hold. Therefore, (13
4) In consideration of equation (117), equation (135) needs to be satisfied.

R2 + rB ≧ r2 + rα (135) ∴rB ≧ rα (136) As described above, in order for the light radiated from the fixed portion 1 not to be received by the infrared light receiving element 4, the formula (88) or (91)
Expression (94) or Expression (97) is satisfied, the expression (117) is satisfied, and (13)
6) Formula must be satisfied.

Next, as shown in FIG. 11, FB is farther from the refracting lens 3 than the light receiving surface, and therefore K1B is the light receiving surface of each optical path from B to FB which comes closest to the infrared light receiving element 4. In a certain case, a condition in which light emitted from B is not received by the infrared light receiving element 4 is shown.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, it is necessary to use FBS1 which is the intersection of K1B and the light receiving surface.
The distance rBS1 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (137) needs to be satisfied.

RBS1> rs (137) As is well known in geometrical optics, r3B1, rB, LB, r
Bs1, f, and L3 are expressed by the following equation (138) as a geometric relationship.
9) Formula is satisfied.

[0285]

[Expression 79]

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (140) as a geometric relationship.
41) Formula is satisfied.

[0287]

[Equation 80]

By substituting equation (141) into equation (139), equation (142) is obtained.

[0289]

[Equation 81]

Also, from Gauss's formula, equation (143)
Equation (144) holds.

[0291]

(Equation 82)

By substituting equation (144) into equation (142), equation (145) is obtained.

[0293]

[Equation 83]

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are represented as geometric relationships (146)
Equation (147) is satisfied.

[0295]

[Equation 84]

By substituting equation (147) into equation (145), equation (148) is obtained.

[0297]

[Equation 85]

Similarly to rBS1, rαS1 is given by the following equation (149).

[0299]

[Equation 86]

Here, of the light paths from α to Fα, the light path closest to the infrared light receiving element 4 on the light receiving surface is K4α, and the equation (150) is established.

RαS1> rαS4 (150) Since rαS4 satisfies the relationship of Expression (84), if Expression (151) is satisfied, rBS1 automatically satisfies the relationship of Expression (137).

RBS1> rαS1 (151) (148) By substituting equation (149) into equation (151), equation (152) is obtained.

[0303]

[Equation 87]

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (153) and (154) hold for Lα and LB.

[0305]

[Equation 88]

An infrared sensor having an optical design that satisfies the condition of the expression (88), the expression (91), the expression (94), or the expression (97) and the expressions (117) and (136) is used. In order to not receive the light emitted from any point other than the tip end surface of the fixed portion, that is, to not receive the light emitted from any point of the fixed portion, it is necessary to set (15
2) The relationship of the expression needs to be satisfied. Therefore, (1
The expression (155) needs to be satisfied in consideration of the expressions (54) and (117).

RB−r2 ≧ rα−r2 (155) ∴rB ≧ rα (156) Equations (156) and (136) are equal. Therefore,
As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (88) or (91)
It is necessary to satisfy the condition of the expression, the expression (94), or the expression (97), the expression (117), and the expression (136).

As described above, according to the present embodiment, the infrared light receiving element 4 is replaced by the expression (88), the expression (91) or the expression (9).
The lens is provided away from the focal point of the refractive lens 3 by an amount given by the expression (4) or (97), and the expressions (117) and (13)
6) By using an optical design that satisfies the expression,
The infrared light from the object to be measured can be received by the infrared light receiving element 4 without receiving the infrared light emitted by the infrared light receiving element 4 from the object to be measured, thereby preventing a measurement error due to a temperature change of the fixed portion. Can be.

The housing 9, the fixed section 1, and the lens aperture stop 2 may be integrated.

FIG. 12 shows an infrared sensor according to the ninth embodiment of the present invention. 12, 5 is a transmission type diffraction lens, 4 is an infrared light receiving element, 9 is a housing, A,
A 'is a point located at a boundary between a region where light reception is desired and a region where light reception is not desired, B is a point of a region where light reception is not desired, F is a focal point of the transmission type diffraction lens, and FA is an image point of A by the transmission type diffraction lens 5. , FA ′ is the image point of A ′ by the transmission type diffraction lens 5, F ′
B is an image point of B by the transmission type diffractive lens 5, K1A is an optical path of light (marginal ray) which travels to A through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis from A.
K2A travels from A in parallel with the optical axis, passes through the focal point F, and
K3A is the transmission diffractive lens 5 from A
K4A is an optical path of light (marginal ray) passing through the center of the lens and arriving at FA through K4A, passing through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis with respect to the optical axis. , K1A 'is the optical path of light (marginal ray) traveling from A' to FA 'through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A' is the optical path from A 'to the optical axis. The optical path of light traveling parallel and passing through the focal point F to reach FA ', K3A'
Is the optical path of the light from A 'to reach FA' through the center of the transmissive diffraction lens 5, and K4A 'is the light path from A passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis with respect to the optical axis. The optical path of the light (marginal ray) reaching FA ', K3B is the optical path of light passing from B through the center of the transmissive diffraction lens 5 and reaching FB, and FX is the intersection of the optical paths K1A and K1A'.

An optical system is designed such that only infrared rays radiated from a region to be measured are received by an infrared light receiving element.

[0312] The infrared light receiving element 4 is attached to the housing 9 so that infrared light not passing through the transmission type diffraction lens 5 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 12, the light passing through the optical path K2A passes through the transmission type diffractive lens 5, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, the light passing through the optical path K1A passes through the transmissive diffraction lens 5, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the transmission type diffractive lens 5, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the transmission diffraction lens 5, and after passing through the transmission diffraction lens 5, reaches the FA without crossing the optical axis. As described above, at a position farther from the transmission diffraction lens than the point FX where the optical path K1A and the optical axis intersect and closer to the transmission diffraction lens 5 than FA, A
There is an area through which the light emitted from does not pass. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The point B outside the region where light is to be received and in the region where light reception is not desired is farther from the optical axis than A, so that the image point FB of B by the transmission type diffraction lens 5 is farther from the optical axis than FA. This is well known. Therefore, FX and FA
By disposing an infrared light receiving element inside the triangle formed by F and FA 'so as not to receive infrared light radiated from A and A', it is possible to automatically receive no infrared light from B.

As described above, by installing the infrared light receiving element 4 inside the triangle formed by FX, FA, and FA ', it becomes possible to receive only infrared light radiated from the light receiving area near the optical axis. An infrared sensor is obtained.

FIG. 13 shows an infrared sensor according to the tenth embodiment of the present invention. In FIG. 13, 5 is a transmission type diffraction lens, 4 is an infrared light receiving element, 9 is a housing, A,
A 'is a point located at a boundary between a region where light reception is desired and a region where light reception is not desired, B is a point of a region where light reception is not desired, F is a focal point of the transmission type diffraction lens, and FA is an image point of A by the transmission type diffraction lens 5. , FA ′ is the image point of A ′ by the transmission type diffraction lens 5, F ′
B is an image point of B by the transmission type diffractive lens 5, K1A is an optical path of light (marginal ray) which travels to A through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis from A.
K2A travels from A in parallel with the optical axis, passes through the focal point F, and
K3A is the transmission diffractive lens 5 from A
K4A is an optical path of light (marginal ray) passing through the center of the lens and arriving at FA through K4A, passing through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis with respect to the optical axis. , K1A 'is the optical path of the light (marginal ray) that travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side as the optical axis, and K2A' is the optical path from A 'to the optical axis. The optical path of light traveling parallel and passing through the focal point F to reach FA ', K3A'
Is the optical path of the light from A 'to reach FA' through the center of the transmissive diffraction lens 5, and K4A 'is the light path from A passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis with respect to the optical axis. K3B is the optical path of light (marginal ray) reaching FA ', K3B is the optical path of light passing from the center of the transmissive diffractive lens 5 to FB, FX is the intersection of optical paths K1A and K1A', and FY is the optical path K
This is the intersection of 4A and the optical path K4A '.

An optical system is designed so that only infrared rays radiated from the area to be measured are received by the infrared light receiving element.

The infrared light receiving element 4 is mounted on the housing 9 so that infrared light not passing through the transmission type diffraction lens 5 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

The light emitted from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 13, the light passing through the optical path K2A passes through the transmission type diffractive lens 5, crosses the optical axis at F, reaches FA, and moves away from the optical axis. Similarly, the light passing through the optical path K1A passes through the transmissive diffraction lens 5, crosses the optical axis, reaches FA, and moves away from the optical axis. Optical path K3A
Passes through the transmission type diffraction lens 5 and intersects with the optical axis.
And moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the transmission type diffraction lens 5, and after passing through the transmission type diffraction lens 5, reaches the FA without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is a region where the light emitted from A does not pass at a position farther from the transmission diffraction lens than the image point FA of A. This region includes an optical path K4A at a portion farther from the transmission diffraction lens 5 than FA, and a transmission diffraction lens 5
This is an area sandwiched between the optical paths K4A 'far from the optical path K4A'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

Since B, which is located outside the region where light is to be received and is not desired to be received, is farther from the optical axis than A, it is unlikely that the image point FB of B by the transmission type diffraction lens 5 is farther from the optical axis than FA. As is well known. Therefore, by installing the infrared light receiving element in a region between the optical path K4A farther from the transmission diffraction lens 5 than FA and the light path K4A 'farther from the transmission diffraction lens 5 than FA'. A,
If you do not receive the infrared radiation emitted from A ',
The configuration is such that infrared rays emitted from B are not automatically received.

As described above, the infrared light is received in the region between the optical path K4A farther from the transmission diffraction lens 5 than FA and the light path K4A 'farther from the transmission diffraction lens 5 than FA'. By installing the element 4, an infrared sensor that receives only infrared light emitted from a light receiving area near the optical axis can be obtained.

FIG. 14 shows an infrared sensor according to the eleventh embodiment of the present invention. In FIG. 14, 5 is a transmission type diffractive lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to a region where light is desired to be received, such as the inside of a hole, and A, A 'is a point located at a boundary between a region where light reception is desired and a region where light reception is not desired, B is a point of a region where light reception is not desired, F is a focal point of a transmission type diffraction lens, F
A is the image point of A by the transmission diffraction lens 5, FA 'is the image point of A' by the transmission diffraction lens 5, FB is the image point of B by the transmission diffraction lens 5, and K1A is from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. K3A passes through the center of the transmission type diffractive lens 5 from A to reach FA, and K4A passes from A through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis. K1A 'is the optical path of the light (marginal ray) reaching FA through the light (marginal ray) which travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis. K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' is K4A 'passes through the center of the transmissive diffractive lens 5 and reaches FA', and K4A 'passes through the edge of the aperture of the lens aperture stop 2 on the opposite side of A from the optical axis and FA'. K3B is the optical path of the light (marginal ray) reaching B, the optical path of the light passing from B through the center of the transmissive diffraction lens 5 to FB, and FX is the optical path K
It is the intersection of 1A and the optical path K1A '.

An optical system is designed such that only infrared rays radiated from a region to be measured near the optical axis are received by the infrared light receiving element.

[0324] The infrared light receiving element 4 is attached to the housing 9, and only the infrared light passing through the transmission type diffraction lens 5 is received by the infrared light receiving element 4.
To receive light. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 14, light passing through the optical path K2A passes through the transmission type diffractive lens 5, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, the light passing through the optical path K1A passes through the transmissive diffraction lens 5, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the transmission type diffractive lens 5, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the transmission diffraction lens 5, and after passing through the transmission diffraction lens 5, reaches the FA without crossing the optical axis. As described above, at a position farther from the transmission diffraction lens than the point FX where the optical path K1A and the optical axis intersect and closer to the transmission diffraction lens 5 than FA, A
There is an area through which the light emitted from does not pass. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The fixed part 1 is set so as to be farther from the optical axis than the optical paths K1A and K1A '.

[0327] The infrared rays radiated from the fixed part 1 are replaced with the light radiated from the area not to receive light on the same surface as the area to receive light. Since point B in the area not to receive light outside the area to receive light is farther from the optical axis than A,
It is well known that the image point FB of B by the transmission diffraction lens 5 is farther from the optical axis than FA. Therefore, if an infrared light receiving element is installed inside the triangle formed by FX, FA and FA 'so as not to receive the infrared light radiated from A and A', the infrared light from B is automatically received. No configuration. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light receiving element 4 is installed inside the triangle formed by FX, FA, and FA ', and the optical path K1A,
By providing the fixing portion 1 farther from the optical axis than K1A ', the infrared sensor can be fixed and directed to an area where light reception is desired in a concave portion such as the inside of a hole, and infrared rays emitted from the fixing portion are received. An infrared sensor that receives only infrared rays radiated from an area to be received near the optical axis without receiving the light is obtained.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIG. 15 shows an infrared sensor according to the twelfth embodiment of the present invention. In FIG. 15, 5 is a transmission type diffractive lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving area such as the inside of a hole in a concave portion, A, A 'is a point located at a boundary between a region where light reception is desired and a region where light reception is not desired, B is a point of a region where light reception is not desired, F is a focal point of a transmission type diffraction lens, F
A is the image point of A by the transmission diffraction lens 5, FA 'is the image point of A' by the transmission diffraction lens 5, FB is the image point of B by the transmission diffraction lens 5, and K1A is from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. K3A passes through the center of the transmission type diffractive lens 5 from A to reach FA, and K4A passes from A through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis. K1A 'is the optical path of the light (marginal ray) reaching FA through the light (marginal ray) which travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis. K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' is K4A 'passes through the center of the transmissive diffractive lens 5 and reaches FA', and K4A 'passes through the edge of the aperture of the lens aperture stop 2 on the opposite side of A from the optical axis and FA'. K3B is the optical path of the light (marginal ray) reaching B, the optical path of the light passing from B through the center of the transmissive diffraction lens 5 to FB, and FX is the optical path K
It is the intersection of 1A and the optical path K1A '.

An optical system is designed such that only infrared rays radiated from a region to be measured near the optical axis are received by the infrared light receiving element.

[0332] The infrared light receiving element 4 is mounted on the housing 9 so that only the infrared light passing through the transmission type diffraction lens 5 is received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 15, the light passing through the optical path K2A passes through the transmission type diffractive lens 5, crosses the optical axis at F, reaches FA, and moves away from the optical axis. Similarly, the light passing through the optical path K1A passes through the transmissive diffraction lens 5, crosses the optical axis, reaches FA, and moves away from the optical axis. Optical path K3A
Passes through the transmission type diffraction lens 5 and intersects with the optical axis.
And moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the transmission type diffraction lens 5, and after passing through the transmission type diffraction lens 5, reaches the FA without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is a region where the light emitted from A does not pass at a position farther from the transmission diffraction lens than the image point FA of A. This region includes an optical path K4A at a portion farther from the transmission diffraction lens 5 than FA, and a transmission diffraction lens 5
This is an area sandwiched between the optical paths K4A 'far from the optical path K4A'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

[0334] The fixed part 1 is installed so as to be farther from the optical axis than the optical paths K1A and K1A '.

[0335] The infrared rays radiated from the fixed part 1 are replaced with the light radiated from the area not desired to be received. Since the point B in the area outside the area where light is not desired to be received is farther from the optical axis than A, the fact that the image point FB of B by the transmission type diffractive lens 5 is farther from the optical axis than FA is due to geometrical optics. As is well known. Therefore, by installing the infrared light receiving element in a region between the optical path K4A farther from the transmission diffraction lens 5 than FA and the light path K4A 'farther from the transmission diffraction lens 5 than FA'. If the infrared rays radiated from A and A ′ are not received, the configuration is such that the infrared rays radiated from B are not automatically received. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light is received in the region between the optical path K4A farther from the transmission diffraction lens 5 than FA and the light path K4A 'farther from the transmission diffraction lens 5 than FA'. The element 4 is installed, and the fixed part 1 is provided farther from the optical axis than the optical paths K1A and K1A 'between A and the transmission type diffractive lens 5, so that an infrared sensor is provided in an area where light is to be received in a concave part such as the inside of a hole. Can be directed in a stable state, and an infrared sensor that receives only infrared rays emitted from an area near the optical axis and desired to be received without receiving infrared rays emitted from the fixed portion can be obtained.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIG. 16 shows an infrared sensor according to a thirteenth embodiment of the present invention. In FIG. 16, reference numeral 5 denotes a transmissive diffraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and pointing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, α, α ′ is the fixed part 1 on the same side from the edge of the transmission diffraction lens 5 with respect to this edge and the optical axis.
The point at which the straight line in contact with the inner surface intersects the front end surface of the fixed portion, F is the focal point of the transmission type diffraction lens 5, Fα and Fα ′ are the image points of α and α ′ by the transmission type diffraction lens 5, respectively, and K1 α is the optical axis from α. , The optical path of light (marginal ray) passing through the edge of the transmission type diffractive lens 5 on the same side and traveling to Fα, K2α travels from α in parallel with the optical axis, passes through the focal point F, and reaches Fα. K3α is the optical path of light passing from α to the center of the transmissive diffractive lens 5 and arriving at Fα, and K4α is the transmissive diffractive lens 5 on the opposite side of the optical axis from α. The optical path of light (marginal ray) passing through and reaching Fα, K1
α ′ is the optical path of light (marginal ray) passing through the edge of the transmissive diffraction lens 5 on the same side from α ′ to the optical axis and traveling to Fα ′, and K2 α ′ is parallel to the optical axis from α ′. K3α 'is the optical path of the light that proceeds to pass through the focal point F and reaches Fα', K3α 'is the optical path of the light from α' that passes through the center of the transmissive diffraction lens 5 and reaches Fα ', and K4α' is α ' Is the optical path of light (marginal ray) passing through the edge of the transmissive diffraction lens 5 on the opposite side of the optical axis and reaching Fα ', FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

The infrared light receiving element 4 is attached to the housing 9 and only infrared light passing through the transmission type diffraction lens 5 is
To receive light. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

In order to receive only infrared light from the object to be measured, infrared light emitted from the fixed section 1 may be prevented from being received. Therefore, a point located at the boundary between the region to receive light and the region not to receive light is imagined, and from this point, the edge of the transmission type diffraction lens 5 on the same side as the point located at this imaginary boundary with respect to the optical axis. Light passing through (marginal rays)
The fixed part 1 is located farther from the optical axis than the optical path of
Should be installed. Therefore, the points located at the above-mentioned virtual boundary are defined as points α and α ′ where the straight line contacting the edge of the transmission type diffraction lens 5 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects with the fixed part tip face The infrared light receiving element 4 is set inside a triangle formed by Fα, Fα ′ and FX. As a result, the fixed portion 1 moves the optical path K between α and the transmission type diffraction lens 5.
Since it is located farther from the optical axis than 1α and K1α ', an optical system that does not receive light from the fixed portion can be obtained.

The above is described in detail below. The light emitted from α reaches the image point Fα of α through the optical paths K1α, K2α, K3α, K4α, and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 16, the light passing through the optical path K2α is
After passing through the transmission diffraction lens 5 and intersecting with the optical axis at F, the light reaches Fα while moving away from the optical axis. Similarly, the light passing through the optical path K1α passes through the transmissive diffraction lens 5, crosses the optical axis, and reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the transmission type diffraction lens 5 and then reaches Fα while leaving the optical axis. Optical path K4
The light passing through α crosses the optical axis and passes through the transmissive diffraction lens 5, and after passing through the transmissive diffraction lens 5, reaches Fα without crossing the optical axis. Thus, at a position farther from the transmission diffraction lens than the point FX where the optical path K1α intersects the optical axis and closer to the transmission diffraction lens 5 than Fα, α
There is an area through which the light emitted from does not pass. Similarly, α ′ is also radiated from α ′ at a position farther from the transmission diffraction lens than at the point where the optical path K1 α ′ intersects with the optical axis and closer to the transmission diffraction lens 5 than Fα ′. There is an area through which light does not pass. This Fα, F
By installing the infrared light receiving element 4 inside the triangle formed by α 'and FX, an infrared sensor that does not receive light emitted from α and α' can be obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the transmission type diffraction lens 5 is
It is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the intersection of this point with the transmission type diffraction lens 5 is farther from the optical axis than Fα. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received, and therefore no light from the fixed portion 1 will be received. Similarly,
Light from a portion farther from the optical axis than the optical path K1 α 'between α' and the transmission type diffractive lens 5 is replaced with light from a point larger than α 'in the same plane as α'. . It is well known in geometrical optics that the intersection of this point with the transmission type diffraction lens 5 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, α ′
No light from a point farther from the optical axis is received, and therefore no light from the fixed part 1 is received. Thus, Fα and Fα ′
By installing the infrared light receiving element 4 inside the triangle formed by F and FX so as not to receive the infrared light radiated from α and α ', the infrared light radiated from the fixed part 1 is automatically received. No configuration.

In the following, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is closer to the transmission type diffraction lens 5 than to FA. At this time, the above-described equation (1) (the same applies hereinafter),
Equation (2) holds.

As shown in FIG. 16, the light receiving surface has an optical path K1 α
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (3).

Here, as is well known in geometrical optics, r3, rα
F, rαS1, L3, and f are expressed by the following equation (4) as a geometric relationship.
Equation (5) is satisfied.

By substituting equation (5) into equation (3), equation (6) is obtained.

(2) From the expression (6), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is the expression (7).

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by the following equation (8) as a geometric relationship.
Equation (9) is satisfied.

By substituting the expression (9) into the expression (7), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 becomes the expression (10).

Also, from Gauss's formula, equation (11), (1
2) Formula holds.

By substituting equation (12) into equation (11), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (13).

As described above, in order to prevent the light radiated from α at the tip of the fixed portion 1 from being received by the infrared light receiving element 4,
It is necessary to design the optical system to satisfy the expression (7), the expression (10), or the expression (13). Equation (7), (1
0) and L3 given by equation (13).
Is displaced from the focal point of the transmissive diffraction lens 5 so that the infrared light emitted from the fixed part 1 is not received by the infrared light receiving element 4 and only the radiation light from the measured object is received by the infrared light receiving element 4.
, It is possible to prevent a measurement error due to a temperature change of the fixed unit 1.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIG. 17 shows an infrared sensor according to a fourteenth embodiment of the present invention. In FIG. 17, 5 is a transmission type diffractive lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving area in a concave portion such as the inside of a hole, α, α ′ is the fixed part 1 on the same side from the edge of the transmission diffraction lens 5 with respect to this edge and the optical axis.
The point at which the straight line in contact with the inner surface intersects the front end surface of the fixed portion, F is the focal point of the transmission type diffraction lens 5, Fα and Fα ′ are the image points of α and α ′ by the transmission type diffraction lens 5, respectively, and K1 α is the optical axis from α. , The optical path of light (marginal ray) passing through the edge of the transmission type diffractive lens 5 on the same side and traveling to Fα, K2α travels from α in parallel with the optical axis, passes through the focal point F, and reaches Fα. K3α is the optical path of light passing from α to the center of the transmissive diffractive lens 5 and arriving at Fα, and K4α is the transmissive diffractive lens 5 on the opposite side of the optical axis from α. The optical path of light (marginal ray) passing through and reaching Fα, K1
α ′ is the optical path of light (marginal ray) passing through the edge of the transmissive diffraction lens 5 on the same side from α ′ to the optical axis and traveling to Fα ′, and K2 α ′ is parallel to the optical axis from α ′. K3α 'is the optical path of the light that proceeds to pass through the focal point F and reaches Fα', K3α 'is the optical path of the light from α' that passes through the center of the transmissive diffraction lens 5 and reaches Fα ', and K4α' is α ' Is the optical path of light (marginal ray) passing through the edge of the transmissive diffraction lens 5 on the opposite side of the optical axis and reaching Fα ', FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

The infrared light receiving element 4 is attached to the housing 9 and only infrared light passing through the transmission type diffraction lens 5 is
To receive light. The following design is performed after a configuration is adopted in which only infrared rays passing through the transmission diffraction lens 5 are received.

In order to receive only infrared light from the object to be measured, infrared light emitted from the fixed section 1 may be prevented from being received. Therefore, a point located at the boundary between the region to receive light and the region not to receive light is imagined, and from this point, the edge of the transmission type diffraction lens 5 on the same side as the point located at this imaginary boundary with respect to the optical axis. Light passing through (marginal rays)
The fixed part 1 is located farther from the optical axis than the optical path of
Should be installed. Therefore, the points located at the above-mentioned virtual boundary are defined as points α and α ′ where the straight line contacting the edge of the transmission type diffraction lens 5 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects with the fixed part tip face. An infrared sensor is installed in a region between the optical path K4α farther from the transmission diffraction lens 5 than Fα and the optical path K4α ′ farther from the transmission diffraction lens 5 than Fα ′. As a result, the fixed unit 1 is located farther from the optical axis than the optical paths K1α and K1α 'between α and the transmission type diffraction lens 5, so that an optical system that does not receive light from the fixed unit is obtained. Can be

The above is described in detail below.

The light radiated from α has the optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 17, light passing through the optical path K2α passes through the transmission type diffraction lens 5 and
Crosses the optical axis to reach Fα and moves away from the optical axis. Similarly, light passing through the optical path K1α is
And crosses the optical axis to reach Fα and moves away from the optical axis. The light passing through the optical path K3α crosses the optical axis by the transmission type diffraction lens 5, reaches Fα and moves away from the optical axis. Optical path K
The light passing through 4α crosses the optical axis and passes through the transmission type diffraction lens 5, and after passing through the transmission type diffraction lens 5, reaches Fα without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is an area where light emitted from α does not pass at a position farther from the transmission diffraction lens than the image point Fα of α. Similarly, for α ',
There is an area where light emitted from α does not pass at a position farther from the transmission diffraction lens than the image point Fα of α. An infrared light receiving element is provided in an area between the optical path K4α farther from the transmissive diffraction lens 5 than Fα and the optical path K4α ′ farther from the transmissive diffraction lens 5 than Fα ′. Thus, an infrared sensor that does not receive infrared rays emitted from α and α ′ can be obtained. Light from a portion farther from the optical axis than the optical path K1α between α and the transmission type diffraction lens 5 is
It is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the intersection of this point with the transmission type diffraction lens 5 is farther from the optical axis than Fα. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received, and therefore no light from the fixed portion 1 will be received. Similarly,
Light from a portion farther from the optical axis than the optical path K1 α 'between α' and the transmission type diffractive lens 5 is replaced with light from a point larger than α 'in the same plane as α'. . It is well known in geometrical optics that the intersection of this point with the transmission type diffraction lens 5 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, α ′
No light from a point farther from the optical axis is received, and therefore no light from the fixed part 1 is received. As described above, the optical path K4α at a portion farther from the transmission diffraction lens 5 than Fα and Fα ′
Optical path K4 α 'at a portion farther from transmission diffractive lens 5 than
By placing the infrared light receiving element 4 in the area between
If you do not receive infrared rays emitted from α ',
The infrared ray emitted from the fixing unit 1 is not automatically received.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is farther from the transmission diffraction lens 5 than Fα. At this time, equations (14) and (15) hold. As shown in FIG. 17, since the light receiving surface is farther from the transmission type diffractive lens 5 than Fα, of the light paths from α to Fα, the light receiving surface closest to the infrared light receiving element 4 is K4.
α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (16).

Here, as is well known in geometrical optics, r3, rα
F, LαF, rαS4, L3, and f are expressed as (1
Equations (7) and (18) are satisfied.

By substituting equation (18) into equation (16), equation (19) is obtained.

From the equations (15) and (19), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (2)
0).

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by a geometric relationship (21)
Equation (22) is satisfied.

By substituting the expression (22) into the expression (20), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the expression (23).

Further, from Gauss's formula, equation (24), (2
5) Formula holds.

By substituting equation (25) into equation (23), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 is given by equation (26).

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the optical system must satisfy the condition of the expression (20), the expression (23) or the expression (26). Need to be designed. Expression (20), Expression (23),
By disposing the light receiving element 4 from the focal point of the transmission type diffractive lens 5 by L3 given by the equation (26), the infrared light emitted from the fixed part 1 is measured without being received by the infrared light receiving element 4. Since only the radiated light from the object can be received by the infrared light receiving element 4, a measurement error due to a temperature change of the fixed portion 1 can be prevented.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIGS. 18 and 19 show an optical system of an infrared sensor according to a fifteenth embodiment of the present invention. FIG.
In 19, 5 is a transmission type diffraction lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving region such as the inside of a hole in a concave portion, 2
Is a lens aperture stop for determining the effective area of the transmission type diffractive lens 5, and α and α 'are fixed portions which are straight lines that contact the edge of the lens aperture stop 2 and the inner surface of the fixed portion 1 on the same side with respect to this edge and the optical axis. A point intersecting with the tip surface, A is a point at the tip of the fixed part 1, B is a point other than the tip of the fixed part 1, F is a focal point of the transmission type diffraction lens 5,
Fα and Fα ′ are α, α by the transmission diffraction lens 5, respectively.
The image point of α ', FA is the image point of A by the transmission type diffraction lens 5, FB is the image point of B by the transmission type diffraction lens 5, K1 α
Is a light (marginal ray) traveling from α to Fα through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis.
K2α is an optical path of light that travels in parallel with the optical axis from α and passes through the focal point F to reach Fα, and K3α is light that travels from α and passes through the center of the transmissive diffraction lens 5 to reach Fα. K4α is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side from α with respect to the optical axis and reaching Fα, and K1A is a light path from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. Light path,
K3A passes through the center of the transmission diffractive lens 5 from A, and
K4A is the optical path of light (marginal ray) from A to the FA that passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis and reaches FA, and K1B is the optical axis from B The light path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the same side and traveling to FB, K2B travels from B in parallel with the optical axis, passes through the focal point F, and enters FB. K3B is the optical path of the light that reaches, and K3B is the optical path of the light that passes from the center of the transmissive diffractive lens 5 to FB, and K4B is the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from B. The optical path of the light (marginal ray) that passes through and reaches FB, Fα
S1 is the intersection of the optical path K1α and the light receiving surface, FAS1 is the intersection of the optical path K1A and the light receiving surface, FBS1 is the intersection of the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the α point, and rA is A The radius of the opening of the fixed part 1 at the point, rB is the opening radius of the fixed part 1 at the point B, r2 is the opening radius of the lens aperture stop 2, and r3 α1 is the optical path K1 α from the optical axis of the transmission diffraction lens 5 The distance, r3A1 is the distance of the optical path K1A from the optical axis in the transmission type diffraction lens 5, and r3B1 is the transmission type diffraction lens 5 of the optical path K1B.
, The distance from the optical axis at, rs is the radius of the infrared light receiving element 4,
rαS1 is the distance between FαS1 and the optical axis, rAS1 is the distance between FAS1 and the optical axis, rBS1 is the distance between FBS1 and the optical axis, and rAF is FA
, The distance between FB and the optical axis, and L α is α
, The distance from A to the lens aperture stop 2, LB is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the transmission diffraction lens 5, f Is the focal length of the transmission diffraction lens 5,
L3 is the distance from F to the infrared light receiving element 4, LαF is the distance from the transmission diffraction lens 5 to Fα, LAF is the distance from the transmission diffraction lens 5 to FA, LBF is the distance from the transmission diffraction lens 5 to FB. Distance.

An optical design condition is determined such that light emitted from any point of the fixed portion is not received by the infrared light receiving element 4. For this purpose, the light radiated from α is imagined, and a design condition for preventing the light from being received by the infrared light receiving element 4 is determined. A condition that light is not received by the element 4 is added.

First, the position of the infrared light receiving element 4 is determined as follows so as not to receive the infrared light radiated from α of the fixed portion 1.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 18, light passing through the optical path K2α passes through the transmission type diffraction lens 5 and
And crosses the optical axis, and then reaches Fα while moving away from the optical axis. Similarly, the light passing through the optical path K1α passes through the transmissive diffraction lens 5, crosses the optical axis, and reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the transmission type diffraction lens 5 and then separates from the optical axis to Fα.
To reach. The light passing through the optical path K4α crosses the optical axis and passes through the transmission type diffraction lens 5, and after passing through the transmission type diffraction lens 5, reaches Fα without crossing the optical axis. As described above, the position of the transmission diffraction lens 5 farther from the transmission diffraction lens than the point where the optical path K1α intersects the optical axis and the transmission diffraction lens 5
At a position close to, there is a region through which light emitted from α does not pass. By arranging the infrared light receiving element 4 at a position farther from the transmissive diffraction lens 5 than the point where the optical path K1α intersects with the optical axis and closer to the transmissive diffraction lens 5 than Fα, the light is radiated from α. An infrared sensor that does not receive light is obtained. Hereinafter, L3 is obtained.

The infrared light receiving element 4 is closer to the transmission diffraction lens 5 than Fα. At this time, equations (27) and (28) hold.

As shown in FIG. 18, the light receiving surface has an optical path K1 α
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (29).

Here, as is well known in geometrical optics, r3 α1,
rαF, LαF, rαS1, L3, and f satisfy Equations (30) and (31) as geometric relationships.

By substituting equation (31) into equation (29), equation (32) is obtained.

From the expressions (28) and (32), the condition for not receiving the light radiated from α by the infrared receiving element 4 is (3)
3) Equation is obtained.

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (34)
Equation (35) is satisfied.

By substituting equation (35) into equation (33), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 is given by equation (36).

Further, from Gauss's formula, equation (37), (3
8) Equation holds.

By substituting the equation (38) into the equation (36), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the equation (39).

As is well known in geometrical optics, r 2, r
α, Lα, r3α1 and L2 are expressed as geometric relationships (40)
Equation (41) is satisfied.

By substituting equation (41) into equation (39), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (42).

As described above, in order for the infrared light receiving element 4 not to receive the light radiated from α at the tip of the fixed portion 1, (3
It is necessary to design the optical system so as to satisfy the condition of the expression (3), the expression (36), the expression (39), or the expression (42).

The infrared sensor whose optical system is designed so as to satisfy the condition of the expression (33), the expression (36), the expression (39), or the expression (42) emits light from a point other than α of the fixed portion. A condition is shown in which no light is received, that is, no light is emitted from any point of the fixed portion. For this purpose, a condition for not receiving light from A and B will be described below with reference to FIG.

First, a condition for not receiving light radiated from A is determined. As shown in FIG. 19, of the light paths from A to FA, the light path closest to the infrared light receiving element 4 on the light receiving surface is K1A. In the case of a fixed portion shape in which A and α do not match, K1A is shielded from light by the fixed portion 1 between A and the lens aperture stop 2, and each optical path does not approach the infrared light receiving element 4 closer to the infrared light receiving element 4 than K1A. Therefore, the condition that the light radiated from A is not received by the infrared light receiving element 4 is that the distance rAS1 between the optical axis and FAS1, which is the intersection of K1A and the light receiving surface, is larger than rs. That is, if the expression (43) is satisfied, the light radiated from A is not received by the infrared light receiving element 4.

As is well known in geometrical optics, r3A1, r3
AF, LA, rAs1, f, and L3 are represented as geometric relationships (44)
Equation (45) is satisfied.

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (46) as a geometric relationship.
7) Formula is satisfied.

By substituting equation (47) into equation (45), equation (48) is obtained.

Also, from Gauss's formula, equation (49), (5
Equation (0) holds.

By substituting equation (50) into equation (48), equation (51) is obtained.

As is well known in geometrical optics, r2, rA
, LA, r3A1 and L2 are expressed by the following equation (52) as a geometric relationship.
Formula (53) is satisfied.

By substituting equation (53) into equation (51), equation (54) is obtained.

Similarly to rAS1, rαS1 is as shown in equation (55).

A is the point at the tip of the fixed part, and α is the point at which the straight line that contacts the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (5
Equation 6) holds, and the distance from the optical axis to A is α from the optical axis.
(57) holds.

By substituting equation (56) into equation (55), equation (58) is obtained.

Since rαS1 satisfies the relationship of equation (29),
If rAS1 is larger than rαS1, that is, if equation (59) is satisfied, rAS1 automatically satisfies the relation of equation (43).

(55) By substituting equation (58) into equation (59), equation (60) is obtained.

From equation (57), equation (60) becomes like equation (61).

As described above, in order to prevent the light radiated from the virtual point α and the tip point A of the fixed portion 1 from being received by the infrared light receiving element 4, the expression (33), the expression (36), or the expression (3)
The condition of the expression 9) or the expression (42) is satisfied, and (6)
It is necessary to satisfy the expression 1).

Next, a condition for not receiving light emitted from B will be determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. Since B is a point other than the tip of the fixed portion, B is closer to the transmission diffraction lens 5 than the point α on the tip surface of the fixed portion. Therefore, as is well known in geometrical optics, the image point FB is farther from the transmission type diffraction lens 5 than the image point Fα of the transmission type diffraction lens 5. That is, equation (62) holds.

The distance from the transmission type diffraction lens 5 to the light receiving surface is smaller than the distance from the transmission type diffraction lens 5 to Fα. Therefore, from equation (62), the distance from the transmission type diffraction lens 5 to the light receiving surface is smaller than the distance from the transmission type diffraction lens 5 to FB.

At this time, as shown in FIG.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1B among the respective optical paths up to. In order to prevent the light emitted from B from being received by the infrared light receiving element 4, the distance rBS1 between the optical axis and FBS1, which is the intersection of K1B and the light receiving surface, needs to be larger than rs. That is, equation (63) needs to be satisfied.

Further, as is well known in geometrical optics, r3B1,
BF, LB, rBs1, f and L3 are expressed as a geometric relation (64)
Equation (65) is satisfied.

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (66) as a geometric relationship.
7) Formula is satisfied.

The equation (68) is obtained by substituting the equation (67) into the equation (65).

Further, from Gauss's formula, equation (69), (7
Equation (0) holds.

The equation (71) is obtained by substituting the equation (70) into the equation (68).

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are expressed by the following equation (72) as a geometric relationship.
Formula (73) is satisfied.

The equation (74) can be obtained by substituting the equation (73) into the equation (71).

Similarly to rBS1, rαS1 is given by equation (75).

Since rαS1 satisfies the relationship of equation (29),
If rBS1 is larger than rαS1, that is, if equation (76) is satisfied, rBS1 automatically satisfies the relation of equation (63).

(77) By substituting equations (75) and (76) into equation (76), equation (77) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (78) and (79) hold for Lα and LB.

An infrared sensor which satisfies the condition of the expression (33), the expression (36), the expression (39), or the expression (42), and the optical system designed to satisfy the expression (61), In order not to receive the radiated light from points other than the surface, the relationship of the equation (77) needs to be established for each point B.

Therefore, it is necessary to satisfy Expression (80) by considering the relationship between Expressions (61) and (79).

As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared receiving element 4, the expression (33), the expression (36), the expression (39), or the expression (42) And the condition (61) is satisfied, and (8)
It is necessary to satisfy the expression 1).

The infrared light receiving element 4 is provided away from the focal plane of the transmission type diffraction lens 5 by an amount given by the expression (33), (36), (39) or (42), and (61) ) And (81), the infrared light emitted from the fixed object is not received by the infrared light receiving element 4 but only the radiated light from the measured object is received by the infrared light receiving element 4. Therefore, it is possible to prevent a measurement error caused by a temperature change of the fixed portion.

[0422] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIGS. 20, 21, and 22 show an optical system of an infrared sensor according to a sixteenth embodiment of the present invention. 20, 21, and 22, reference numeral 5 denotes a transmission diffraction lens,
Is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, and 2 is a fixing portion for determining an effective region of the transmission type diffraction lens 5. Α, α ′ are points where a straight line contacting the edge of the lens aperture stop 2 from the edge of the lens aperture stop 2 to the inner surface of the fixed portion 1 on the same side with respect to the optical axis intersects with the front surface of the fixed portion, and A is the tip of the fixed portion 1 Point, B is a point other than the tip of the fixed portion 1, F is the focal point of the transmission type diffraction lens 5, Fα and Fα ′ are the image points of α and α ′ by the transmission type diffraction lens 5, respectively, and FA is the transmission type diffraction lens 5.
Is the image point of A, FB is the image point of B by the transmission type diffraction lens 5, and K1α is the light traveling from α to Fα through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis. The optical path of (marginal ray), K2α is the optical path of light traveling parallel to the optical axis from α and passing through the focal point F to reach Fα, and K3α is Fα passing from α and passing through the center of the transmissive diffraction lens 5. K4α is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side from α with respect to the optical axis and reaching Fα, and K1A is an optical path from A. Passing through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the axis,
The optical path of the light (marginal ray) traveling to A, K2A is the optical path of the light traveling parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is passing from A to the center of the transmission diffractive lens 5. K4A is the optical path of the light that reaches FA, K4A is the optical path of the light (marginal ray) that passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from A and reaches FA, and K1B is B
K2B passes through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis and travels to FB (marginal ray). K2B travels from B in parallel with the optical axis and passes through the focal point F. K3B is the optical path of light that reaches FB from B through the center of the transmission type diffractive lens 5, and K4B is the aperture of the lens aperture stop 2 opposite the optical axis from B with respect to the optical axis. The optical path of the light (marginal ray) passing through the edge of the part and reaching FB, FαS4 is the intersection of the optical path K4α with the light receiving surface, FAS4 is the intersection of the optical path K4A and the light receiving surface, and FBS4 is the optical path K4B and the sensor surface. , The intersection of the optical path K1A and the light receiving surface, FBS
1 is the intersection of the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the point α, rA is the opening radius of the fixed part 1 at the point A,
rB is the aperture radius of the fixed portion 1 at the point B, r2 is the aperture radius of the lens aperture stop 2, r3.alpha.4 is the distance of the optical path K4.alpha. from the optical axis of the transmission diffraction lens 5, and r3A4 is the transmission diffraction of the optical path K4A. The distance of the lens 5 from the optical axis, r3B4 is the distance of the optical path K4B from the optical axis of the transmission diffraction lens 5, r3 α1 is the distance of the optical path K1 α from the optical axis of the transmission diffraction lens 5, and r3B1 is the distance of the optical path K1B. The distance from the optical axis in the transmission diffraction lens 5, rs is the radius of the infrared light receiving element 4, rαS4 is the distance between FαS4 and the optical axis, rAS4 is the distance between FAS4 and the optical axis, and rBS4 is the distance between FBS4 and the optical axis. Distance, rαS1
Is the distance between FαS1 and the optical axis, rBS1 is the distance between FBS1 and the optical axis, rαF is the distance between Fα and the optical axis, rAF is the distance between FA and the optical axis, rBF is the distance between FB and the optical axis, L α is the distance from α to the lens aperture stop 2, and LA is the distance from A to the lens aperture stop 2.
, LB is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the transmission diffraction lens 5, f is the focal length of the transmission diffraction lens 5, L3 is the infrared reception from F. LαF is the distance from the transmission diffraction lens 5 to Fα, LAF is the distance from the transmission diffraction lens 5 to FA, and LBF is the distance from the transmission diffraction lens 5 to FB.

The infrared light emitted from α on the fixed portion 1 is assumed, and the position of the infrared light receiving element 4 is determined as described below so as not to receive this light.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 20, light passing through the optical path K2α passes through the transmission type diffraction lens 5 and
Crosses the optical axis to reach Fα and moves away from the optical axis. Similarly, light passing through the optical path K1α is
And crosses the optical axis to reach Fα and moves away from the optical axis. The light passing through the optical path K3α crosses the optical axis by the transmission type diffraction lens 5, reaches Fα and moves away from the optical axis. Optical path K
The light passing through 4α crosses the optical axis and passes through the transmission type diffraction lens 5, and after passing through the transmission type diffraction lens 5, reaches Fα without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is an area where light emitted from α does not pass at a position farther from the transmission diffraction lens than the image point Fα of α. By installing the infrared light receiving element 4 at a position further away from the transmission diffraction lens 5 than the image point Fα of α, an infrared sensor that does not receive light emitted from α can be obtained. Hereinafter, the distance L3 from the focal point of the transmission type diffraction lens 5 to the light receiving surface is obtained.

The infrared light receiving element 4 is farther from the transmission diffraction lens 5 than Fα. At this time, equations (82) and (83) hold. As shown in FIG. 20, since the light receiving surface is farther from the transmission diffractive lens 5 than Fα, of the light paths from α to Fα, the light receiving surface closest to the infrared light receiving element 4 is K4.
α. Therefore, in order for the infrared light receiving element 4 not to receive the light from α, it is necessary to satisfy the expression (84).

Here, as is well known in geometrical optics, r3 α4,
rαF, LαF, rαS4, L3, and f satisfy the equations (85) and (86) as geometric relationships.

The equation (87) is obtained by substituting the equation (86) into the equation (84).

From the equations (83) and (87), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (8
8)

Furthermore, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (89)
Equation (90) is satisfied.

By substituting equation (90) into equation (88), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (91).

Further, from Gauss's formula, equation (92), (9
3) Equation holds.

By substituting the expression (93) into the expression (91), the condition for preventing the light radiated from α from being received by the infrared receiving element 4 becomes the expression (94).

As is well known in geometrical optics, r2, r
α, Lα, r3α4, L2 are expressed as a geometric relationship (95)
Equation (96) is satisfied.

By substituting the expression (96) into the expression (94), the condition for preventing the light radiated from α from being received by the infrared receiving element 4 becomes the expression (97).

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to design an optical system to satisfy the conditions.

The infrared sensor whose optical system is designed to satisfy the condition of the expression (88), the expression (91), the expression (94) or the expression (97) emits light from a point other than α on the fixed portion. A condition is shown in which no light is received, that is, no light is emitted from any point of the fixed portion. For this purpose, conditions for not receiving light from A and B will be obtained below with reference to FIGS.

First, a condition for not receiving the light radiated from A is determined according to FIG. A to transmission diffractive lens 5
And the distance between α and the transmission diffractive lens 5 are equal, so that the image points FA and Fα of A and α by the transmission diffractive lens 5 are formed in the same plane as is well known in geometrical optics.
Accordingly, since the light receiving surface is farther from the transmission diffraction lens 5 than Fα, the light receiving surface is farther than FA. Therefore, as shown in FIG. 21, K4A is the light path closest to the infrared light receiving element 4 on the light receiving surface among the light paths from A to FA. A
In order not to receive the light radiated from the infrared light receiving element 4, the distance rAS4 between the optical axis and FAS4, which is the intersection point between K4A and the light receiving surface, needs to be larger than rs.

That is, equation (98) needs to be satisfied.

As is well known in geometrical optics, r3A4, r3
AF, LAF, rAs4, f, and L3 are expressed as a geometric relationship (99)
Equation (100) is satisfied.

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (101) as a geometric relationship.
02) is satisfied.

By substituting equation (102) into equation (100), equation (103) is obtained.

Also, from Gauss's formula, equation (104)
Equation (105) holds.

By substituting equation (105) into equation (103), equation (106) is obtained.

As is well known in geometrical optics, r2, rA
, LA, r3A4, and L2 are expressed as geometric relationships (107)
Equation (108) is satisfied.

By substituting equation (108) into equation (106), equation (109) is obtained.

Similarly to rAS4, rαS4 is as shown in equation (110).

Since rαS4 satisfies the relationship of equation (84),
If equation (111) is satisfied, rAS4 automatically satisfies the relation of equation (98).

(109) By substituting equation (110) into equation (111), equation (112) is obtained.

A is the point at the tip of the fixed part, and α is the point at which the straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (1
Expression 13) holds, and the distance from the optical axis to A is equal to or greater than the distance from the optical axis to α, and Expression (114) holds.

From the expression (113), the condition of the expression (112) is as shown in the expression (115).

From the expression (114), the conditions of the expression (115) are as shown in the expressions (116) and (117).

The infrared sensor, whose optical constants and positional relationships are designed to satisfy the conditions of Expression (88), Expression (91), Expression (94), or Expression (97), In order not to receive the radiated light, the optical design needs to satisfy the condition of the expression (117).

Next, a condition for not receiving light emitted from B will be determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. B to FB
The light path closest to the infrared light receiving element 4 on the light receiving surface is K4B when the image point FB is closer to the transmission diffraction lens 5 than the light receiving surface as shown in FIG.
If the image point FB is closer to the transmission diffraction lens 5 than the light receiving surface as shown in FIG.

First, as shown in FIG. 21, FB is closer to the transmissive diffraction lens 5 than the light receiving surface.
In the case where K4B is the light receiving surface closest to the infrared light receiving element 4 among the light paths up to K4B, the conditions under which the light emitted from B is not received by the infrared light receiving element 4 are shown.

In order for the infrared light receiving element 4 not to receive the light radiated from B, it is necessary to use FBS4, which is the intersection of K4B and the light receiving surface.
The distance rBS4 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (118) needs to be satisfied.

As is well known in geometrical optics, r3B4, r3
BF, LBF, rBs4, f, and L3 are represented as (11
Equations 9) and (120) are satisfied.

Further, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (121) as a geometric relationship.
22) Formula is satisfied.

By substituting equation (122) into equation (120), equation (123) is obtained.

Also, from Gauss's formula, equation (124)
Equation (125) holds.

By substituting equation (125) into equation (123), equation (126) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B4, and L2 are expressed as geometric relationships (127)
Equation (128) is satisfied.

By substituting equation (128) into equation (126), equation (129) is obtained.

[0464] Similarly to rBS4, rαS4 is given by equation (130).

Since rαS4 satisfies the relationship of equation (84),
If equation (131) is satisfied, rBS4 automatically becomes (118)
This satisfies the relationship of the expression.

(129) By substituting equation (130) into equation (131), equation (132) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of the equations (133) and (134) hold for Lα and LB.

The condition of the expression (88), the expression (91), the expression (94), or the expression (97) is satisfied, and (11)
The infrared sensor designed with the optical constants and each positional relationship according to the condition of the expression 7) does not receive the light emitted from any point other than the tip of the fixed part, that is, does not receive the light emitted from any point of the fixed part. To do this, for any B (132)
It is necessary that the relationship of the expressions hold. Therefore, (13
4) In consideration of equation (117), equation (135) needs to be satisfied. As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, (88)
Expression, or Expression (91), Expression (94), or Expression (9)
It is necessary to satisfy the condition of the expression (7), the condition of the expression (117), and the expression (136).

Next, as shown in FIG. 22, FB is farther from the transmissive diffractive lens 5 than the light receiving surface, and therefore, among the optical paths from B to FB, the one closest to the infrared light receiving element 4 on the light receiving surface. In the case of K1B, a condition that light emitted from B is not received by the infrared light receiving element 4 is shown.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, it is necessary to use FBS1 at the intersection of K1B and the light receiving surface.
The distance rBS1 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (137) needs to be satisfied.

As is well known in geometrical optics, r3B1, r3
B, LB, rBs1, f, and L3 are expressed as geometric relationships (13
8) and (139) are satisfied.

Further, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (140) as a geometric relationship.
41) Formula is satisfied.

By substituting equation (141) into equation (139), equation (142) is obtained.

Also, from Gauss's formula, equation (143)
Equation (144) holds.

By substituting equation (144) into equation (142), equation (145) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are represented as geometric relationships (146)
Equation (147) is satisfied.

By substituting equation (147) into equation (145), equation (148) is obtained.

Similarly to rBS1, rαS1 is as shown in equation (149).

Here, of the respective optical paths from α to Fα, the one closest to the infrared light receiving element 4 on the light receiving surface is K4α, and the equation (150) is established.

Since rαS4 satisfies the relationship of equation (84),
If equation (151) is satisfied, rBS1 automatically becomes (137)
This satisfies the relationship of the expression.

(148) By substituting equation (149) into equation (151), equation (152) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of the equations (153) and (154) are established for Lα and LB.

An infrared sensor having an optical design that satisfies the condition of the expression (88), the expression (91), the expression (94), or the expression (97) and the expressions (117) and (136) is used. In order to not receive the light emitted from any point other than the tip end surface of the fixed portion, that is, to not receive the light emitted from any point of the fixed portion, it is necessary to set (15
2) The relationship of the expression needs to be satisfied. Therefore, (1
The expression (155) needs to be satisfied in consideration of the expressions (54) and (117).

The equations (156) and (136) are equal.
Therefore, as described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to satisfy the condition, satisfy the expression (117), and further satisfy the expression (136).

As described above, according to the present embodiment, the infrared light receiving element 4 is replaced by the expression (88), the expression (91), or the expression (9).
By providing an optical design that is provided away from the focal point of the transmissive diffraction lens 5 by an amount given by Expression 4) or Expression (97) and that satisfies Expressions (117) and (136), radiation from the fixed unit 1 is obtained. Since only infrared radiation from the object to be measured can be received by the infrared light receiving element 4 without receiving infrared light by the infrared light receiving element 4, a measurement error due to a temperature change of the fixed portion can be prevented.

[0486] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIG. 23 shows an infrared sensor according to a seventeenth embodiment of the present invention. In FIG. 23, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, A and A 'are points located at a boundary between a region to receive light and a region not to receive light, and B is a region located not to receive light. F, F is the focal point of the condenser mirror, FA is the image point of A by the condenser mirror 6, FA 'is the image point of A' by the condenser mirror 6, and FB is B of the condenser mirror 6.
K1A is an optical path of light (marginal ray) traveling from A to the FA through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A is parallel to the optical axis from A. K3A is an optical path of light that travels through the focal point F to reach FA, K3A is an optical path of light that passes from the center of the condenser mirror 6 to reach FA, and K4A is an optical path from A opposite to the optical axis. K1A ', the optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 and arriving at FA, passes through the edge of the aperture of the lens aperture stop 2 on the same side from A' with respect to the optical axis. K2A 'is an optical path of light (marginal ray) traveling parallel to the optical axis from A' and passing through the focal point F to reach FA ', and K3A' is a light path from A '. K4A 'is an optical path of light passing through the center of the optical mirror 6 and arriving at FA'; K4A 'is an opening of the lens aperture stop 2 on the opposite side of A from the optical axis. FA passes through the edge '
K3B is the optical path of the light reaching the FB from B through the center of the converging mirror 6, and FX is the intersection of the optical paths K1A and K1A '.

An optical system is designed such that only infrared rays emitted from the region to be measured are received by the infrared light receiving element.

[0489] The infrared light receiving element 4 is attached to the housing 9 so that infrared light not passing through the condenser mirror 6 is not received by the infrared light receiving element 4. The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 23, the light passing through the optical path K2A passes through the condenser mirror 6, intersects the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, light passing through the optical path K1A passes through the condenser mirror 6, crosses the optical axis, and then reaches FA while leaving the optical axis. Optical path K3A
Passes through the condenser mirror 6 and crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the collecting mirror 6, and after passing through the collecting mirror 6, reaches the FA without crossing the optical axis. As described above, there is a region where the light radiated from A does not pass at a position farther from the converging mirror than the point FX where the optical path K1A intersects with the optical axis and closer to the converging mirror 6 than FA. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The point B outside the region where light is to be received and in the region where light reception is not desired is farther from the optical axis than A, so that the image point FB of B by the condenser mirror 6 is farther from the optical axis than FA. Is well known. Therefore, FX, FA and FA '
By disposing the infrared light receiving element inside the triangle formed by the light receiving element so as not to receive the infrared light radiated from A and A ′, the infrared light from B is not automatically received.

As described above, by arranging the infrared light receiving element 4 inside the triangle formed by FX, FA, and FA ', it is possible to receive only the infrared light radiated from the light receiving area near the optical axis. An infrared sensor is obtained.

FIG. 24 shows an infrared sensor according to the eighteenth embodiment of the present invention. In FIG. 24, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, A and A 'are points located at a boundary between a region where light reception is desired and a region where light reception is not desired, and B is a region where light reception is not desired. F, F is the focal point of the condenser mirror, FA is the image point of A by the condenser mirror 6, FA 'is the image point of A' by the condenser mirror 6, and FB is B of the condenser mirror 6.
K1A is an optical path of light (marginal ray) traveling from A to the FA through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A is parallel to the optical axis from A. K3A is an optical path of light that travels through the focal point F to reach FA, K3A is an optical path of light that passes from the center of the condenser mirror 6 to reach FA, and K4A is an optical path from A opposite to the optical axis. K1A ', the optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 and arriving at FA, passes through the edge of the aperture of the lens aperture stop 2 on the same side from A' with respect to the optical axis. K2A 'is an optical path of light (marginal ray) traveling parallel to the optical axis from A' and passing through the focal point F to reach FA ', and K3A' is a light path from A '. K4A 'is an optical path of light passing through the center of the optical mirror 6 and arriving at FA'; K4A 'is an opening of the lens aperture stop 2 on the opposite side of A from the optical axis. FA passes through the edge '
K3B is the optical path of light reaching the FB from B through the center of the focusing mirror 6, FX is the intersection of the optical paths K1A and K1A ', and FY is the optical path K
This is the intersection of 4A and the optical path K4A '.

[0494] An optical system is designed so that only infrared rays radiated from the area to be measured are received by the infrared light receiving element.

[0495] The infrared light receiving element 4 is attached to the housing 9 so that infrared light not passing through the condenser mirror 6 is not received by the infrared light receiving element 4. The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 24, the light passing through the optical path K2A passes through the condenser mirror 6 and intersects the optical axis at F at F.
It reaches A and moves away from the optical axis. Similarly, the optical path K1A
Passes through the condenser mirror 6, crosses the optical axis, and
It reaches A and moves away from the optical axis. The light passing through the optical path K3A is
The light converging mirror 6 crosses the optical axis to reach FA and moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, reaches the FA without crossing the optical axis, and then approaches the optical axis or Go away. As described above, there is an area where the light emitted from A does not pass at a position farther from the collecting mirror than the image point FA of A. This region is a region sandwiched between an optical path K4A farther from the light collecting mirror 6 than FA and a light path K4A 'farther from the light collecting mirror 6 than FA'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

It is well known that B in an area outside the area where light is desired to be received and not in the area where light is not desired is farther from the optical axis than A, so that the image point FB of B by the condenser mirror 6 is farther from the optical axis than FA. It is as follows. Therefore, the optical path K4A at a portion farther from the converging mirror 6 than FA and the converging mirror 6
If the infrared ray radiated from A and A 'is prevented from being received by installing the infrared ray detector in the area between the optical paths K4A' far from the The configuration does not receive light.

As described above, the infrared light receiving element 4 is located within the region sandwiched between the optical path K4A farther from the converging mirror 6 than FA and the optical path K4A 'farther from the converging mirror 6 than FA'. Is provided, an infrared sensor that receives only infrared rays emitted from a region near the optical axis that is desired to be received can be obtained.

FIG. 25 shows an infrared sensor according to a nineteenth embodiment of the present invention. In FIG. 25, reference numeral 6 denotes a condensing mirror, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to an area to receive light in a concave portion such as the inside of a hole, and A and A. 'Is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the condenser mirror, FA is an image point of A by the condenser mirror 6, FA' Is the image point of A 'by the condenser mirror 6, FB is the image point of B by the condenser mirror 6, K1A is FA from the A through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis. K2A is an optical path of light (marginal ray) traveling in parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is an optical path from A passing through the center of the focusing mirror 6 from A. The optical path of light reaching FA, K4A, passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from A. The optical path of the light (marginal light) that reaches the FA,
K1A 'is the optical path of the light (marginal ray) traveling from A' to FA 'through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A' is parallel from A 'to the optical axis. K3A 'is the optical path of light that reaches the point FA' through the focal point F, K3A 'is the optical path of the light that reaches the point FA' through the center of the condenser mirror 6, and K4A 'is the optical axis from the point A. K3B is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the lens and reaching FA '.
Is the optical path of the light that reaches the FB through the center of the optical path, and FX is the intersection of the optical paths K1A and K1A '.

An optical system is designed such that only infrared rays radiated from an area to be measured near the optical axis are received by the infrared light receiving element.

[0501] The infrared light receiving element 4 is attached to the housing 9, and only the infrared light passing through the condenser mirror 6 is received by the infrared light receiving element 4. The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 25, the light passing through the optical path K2A passes through the condenser mirror 6, intersects the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, light passing through the optical path K1A passes through the condenser mirror 6, crosses the optical axis, and then reaches FA while leaving the optical axis. Optical path K3A
Passes through the condenser mirror 6 and crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the collecting mirror 6, and after passing through the collecting mirror 6, reaches the FA without crossing the optical axis. As described above, there is a region where the light radiated from A does not pass at a position farther from the converging mirror than the point FX where the optical path K1A intersects with the optical axis and closer to the converging mirror 6 than FA. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The fixed part 1 is set so as to be farther from the optical axis than the optical paths K1A and K1A '.

[0504] The infrared rays radiated from the fixed portion 1 are replaced with the light radiated from the area on the same surface as the area on which light reception is not desired. Since point B in the area not to receive light outside the area to receive light is farther from the optical axis than A,
It is well known that the image point FB of B by the condenser mirror 6 is farther from the optical axis than FA. Therefore, if an infrared light receiving element is installed inside the triangle formed by FX, FA and FA 'so as not to receive the infrared light radiated from A and A', the infrared light from B is automatically received. No configuration. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light receiving element 4 is installed inside the triangle formed by FX, FA, and FA ', and the optical path K1A,
By providing the fixing portion 1 farther from the optical axis than K1A ', the infrared sensor can be fixed and directed to an area where light reception is desired in a concave portion such as the inside of a hole, and infrared rays emitted from the fixing portion are received. An infrared sensor that receives only infrared rays radiated from an area to be received near the optical axis without receiving the light is obtained.

[0506] The housing 9 and the fixed portion 1 may be integrated.

FIG. 26 shows an infrared sensor according to the twentieth embodiment of the present invention. In FIG. 26, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving area in a concave portion such as the inside of a hole, and A and A. 'Is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the condenser mirror, FA is an image point of A by the condenser mirror 6, FA' Is the image point of A 'by the condenser mirror 6, FB is the image point of B by the condenser mirror 6, K1A is FA from the A through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis. K2A is an optical path of light (marginal ray) traveling in parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is an optical path from A passing through the center of the focusing mirror 6 from A. The optical path of light reaching FA, K4A, passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from A. The optical path of the light (marginal light) that reaches the FA,
K1A 'is the optical path of the light (marginal ray) traveling from A' to FA 'through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis, and K2A' is parallel from A 'to the optical axis. K3A 'is the optical path of light that reaches the point FA' through the focal point F, K3A 'is the optical path of the light that reaches the point FA' through the center of the condenser mirror 6, and K4A 'is the optical axis from the point A. K3B is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the lens and reaching FA '.
Is the optical path of the light that reaches the FB through the center of the optical path, and FX is the intersection of the optical paths K1A and K1A '.

An optical system is designed such that only infrared rays radiated from the region to be measured near the optical axis are received by the infrared light receiving element.

[0509] The housing 9 is arranged so that the infrared receiving element 4 receives only infrared light passing through the condenser mirror 6.
Attach to The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 26, the light passing through the optical path K2A passes through the condenser mirror 6 and intersects the optical axis at F at F.
It reaches A and moves away from the optical axis. Similarly, the optical path K1A
Passes through the condenser mirror 6, crosses the optical axis, and
It reaches A and moves away from the optical axis. The light passing through the optical path K3A is
The light converging mirror 6 crosses the optical axis to reach FA and moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, reaches the FA without crossing the optical axis, and then approaches the optical axis or Go away. As described above, there is an area where the light emitted from A does not pass at a position farther from the collecting mirror than the image point FA of A. This region is a region sandwiched between an optical path K4A farther from the light collecting mirror 6 than FA and a light path K4A 'farther from the light collecting mirror 6 than FA'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

[0511] The fixed part 1 is installed so as to be farther from the optical axis than the optical paths K1A and K1A '.

[0512] The infrared light emitted from the fixed portion 1 is replaced with light emitted from an area where light reception is not desired. It is well known in geometrical optics that the point B in the area outside the area where light is not desired to be received is farther from the optical axis than A, so that the image point FB of B by the condenser mirror 6 is farther from the optical axis than FA. It is as follows. Therefore, by installing an infrared light receiving element in a region sandwiched between the optical path K4A at a portion farther from the converging mirror 6 than FA and the optical path K4A 'at a portion farther from the converging mirror 6 than FA', A If the infrared rays emitted from A 'are not received, the infrared rays emitted from B are not automatically received. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

[0513] As described above, the infrared light receiving element 4 is located in the region sandwiched between the optical path K4A farther from the converging mirror 6 than FA and the light path K4A 'farther from the converging mirror 6 than FA'. Is installed, and the fixed part 1 is connected to the optical path K between A and the condenser mirror 6.
By providing the infrared sensor farther from the optical axis than 1A and K1A ', the infrared sensor can be stably directed to the area where light is to be received, such as the inside of a hole, in a concave portion, without receiving infrared light radiated from the fixed part. Thus, an infrared sensor that receives only infrared rays radiated from a region desired to be received near the optical axis can be obtained.

[0514] The housing 9 and the fixed portion 1 may be integrated.

FIG. 27 shows an infrared sensor according to a twenty-first embodiment of the present invention. In FIG. 27, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving area such as the inside of a hole in a concave portion, α, α 'Is a point where a straight line from the edge of the converging mirror 6 to the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects the front end face of the fixed part, F is the focal point of the condensing mirror 6, Fα, Fα' Α by the condenser mirror 6,
The image point of α ', K1 α is the optical path of light (marginal ray) traveling from F to Fα through the edge of the condenser mirror 6 on the same side with respect to the optical axis, and K2 α is parallel from α to the optical axis. , The optical path of light passing through the focal point F and arriving at Fα, K3α is the optical path of light arriving from α and passing through the center of the focusing mirror 6 to Fα, and K4α is interposing the optical axis from α. Condensing mirror 6 on the other side
K1α 'is an optical path of light (marginal ray) that passes through the edge of F and arrives at Fα. Light that travels from α ′ to Fα ′ through the edge of the converging mirror 6 on the same side with respect to the optical axis ( K2 α 'is an optical path of light which travels from α' in parallel with the optical axis, passes through the focal point F and reaches Fα ', K3 α'
Is the optical path of light from α ′ to the Fα ′ through the center of the condensing mirror 6 and K4 α ′ is Fα ′ from α ′ passing through the edge of the condensing mirror 6 on the opposite side of the optical axis with respect to the optical axis. Is the optical path of the light (marginal ray) reaching the optical path, and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

[0517] The infrared light receiving element 4 is attached to the housing 9, and only the infrared light passing through the condenser mirror 6 is received by the infrared light receiving element 4. The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

[0518] In order to receive only infrared light from the object to be measured, infrared light radiated from the fixed portion 1 may be prevented from being received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the light passes through the edge of the condenser mirror 6 on the same side as the point located at this virtual boundary with respect to the optical axis. The fixing unit 1 may be installed so as to be located farther from the optical axis than the optical path of the light (marginal ray). Therefore, the point located on the virtual boundary is
A point α at which a straight line that contacts the inner surface of the fixed portion 1 on the same side as the edge and the optical axis from the edge of the condensing mirror 6 intersects with the fixed portion tip surface,
As α ′, the infrared light receiving element 4 is installed inside a triangle formed by Fα, Fα ′ and FX. As a result, the fixed unit 1 is located farther from the optical axis than the optical paths K1α and K1α ′ between α and the condenser mirror 6, so that an optical system that does not receive light from the fixed unit can be obtained. .

The above will be described in detail below. The light emitted from α reaches the image point Fα of α through the optical paths K1α, K2α, K3α, K4α, and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 27, the light passing through the optical path K2α is
After passing through the condenser mirror 6 and intersecting with the optical axis at F, the light reaches Fα while leaving the optical axis. Similarly, the optical path K1 α
Passes through the condenser mirror 6, crosses the optical axis, and then reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the condenser mirror 6 and then reaches Fα while leaving the optical axis. The light passing through the optical path K4α crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, reaches Fα without crossing the optical axis. As described above, there is a region where the light emitted from α does not pass at a position farther from the collecting mirror than the point FX where the optical path K1α intersects the optical axis and closer to the collecting mirror 6 than Fα. .

Similarly, for α ′, the optical path K1
There is an area where light emitted from α ′ does not pass, at a position farther from the condenser mirror than at a point where α ′ intersects with the optical axis and closer to the condenser mirror 6 than at Fα ′. This, F
By installing the infrared light receiving element 4 inside the triangle formed by α, Fα ′ and FX, an infrared sensor that does not receive light emitted from α and α ′ can be obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the converging mirror 6 is
It is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the point of intersection of this point by the condenser mirror 6 is farther from the optical axis than Fα. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received,
Therefore, it does not receive light from the fixed part 1. Similarly, light from a portion farther from the optical axis than the optical path K1α 'between α' and the condenser mirror 6 is light from a point larger than α 'in the same plane as α'. Be replaced. It is well known in geometrical optics that the point of intersection of this point by the condenser mirror 6 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, light from a point farther from the optical axis than α ′ will not be received, and therefore no light from the fixed portion 1 will be received. Thus, by placing the infrared light receiving element 4 inside the triangle formed by Fα, Fα ′ and FX, α,
If you do not receive infrared rays emitted from α ',
The infrared ray emitted from the fixing unit 1 is not automatically received.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

[0522] The infrared light receiving element 4 is more converging mirror 6 than FA.
Close to. At this time, equations (1) and (2) hold.

As shown in FIG. 27, the light receiving surface has an optical path K1 α
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (3).

Here, as is well known in geometrical optics, r3, rα
F, rαS1, L3, and f are expressed by the following equation (4) as a geometric relationship.
Equation (5) is satisfied.

The equation (6) can be obtained by substituting the equation (5) into the equation (3).

From the expressions (2) and (6), the condition for not receiving the light emitted from α by the infrared light receiving element 4 is the expression (7).

Furthermore, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by the following equation (8) as a geometric relationship.
Equation (9) is satisfied.

By substituting the expression (9) into the expression (7), the condition for preventing the light radiated from α from being received by the infrared receiving element 4 becomes the expression (10).

Also, from Gauss's formula, equation (11), (1
2) Formula holds.

By substituting equation (12) into equation (11), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (13).

As described above, in order for the infrared light receiving element 4 not to receive the light radiated from α at the tip of the fixed portion 1,
It is necessary to design the optical system to satisfy the expression (7), the expression (10), or the expression (13). Equation (7), (1
0) and L3 given by equation (13).
Is displaced from the focal point of the focusing mirror 6 so that the infrared light emitted from the fixed part 1 is not received by the infrared light receiving element 4 but only the radiated light from the measured object is received by the infrared light receiving element 4. Therefore, it is possible to prevent a measurement error caused by a temperature change of the fixed unit 1.

[0532] The housing 9 and the fixing portion 1 may be integrated.

FIG. 28 shows an infrared sensor according to the twenty-second embodiment of the present invention. In FIG. 28, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to a light receiving region such as the inside of a hole in a concave portion, α, α 'Is a point where a straight line from the edge of the converging mirror 6 to the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects the front end face of the fixed part, F is the focal point of the condensing mirror 6, Fα, Fα' Α by the condenser mirror 6,
The image point of α ', K1 α is the optical path of light (marginal ray) traveling from F to Fα through the edge of the condenser mirror 6 on the same side with respect to the optical axis, and K2 α is parallel from α to the optical axis. , The optical path of light passing through the focal point F and arriving at Fα, K3α is the optical path of light arriving from α and passing through the center of the focusing mirror 6 to Fα, and K4α is interposing the optical axis from α. Condensing mirror 6 on the other side
K1α 'is an optical path of light (marginal ray) that passes through the edge of F and arrives at Fα. Light that travels from α ′ to Fα ′ through the edge of the converging mirror 6 on the same side with respect to the optical axis ( K2 α 'is an optical path of light which travels from α' in parallel with the optical axis, passes through the focal point F and reaches Fα ', K3 α'
Is the optical path of light from α ′ to the Fα ′ through the center of the condensing mirror 6 and K4 α ′ is Fα ′ from α ′ passing through the edge of the condensing mirror 6 on the opposite side of the optical axis with respect to the optical axis. Is the optical path of the light (marginal ray) reaching the optical path, and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

[0535] The infrared light receiving element 4 is attached to the housing 9, and only infrared light passing through the condenser mirror 6 is received by the infrared light receiving element 4. The following design is performed after the configuration is such that only infrared rays passing through the condenser mirror 6 are received.

In order to receive only infrared light from the object to be measured, infrared light emitted from the fixed section 1 may be prevented from being received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the light passes through the edge of the condenser mirror 6 on the same side as the point located at this virtual boundary with respect to the optical axis. The fixing unit 1 may be installed so as to be located farther from the optical axis than the optical path of the light (marginal ray). Therefore, the point located on the virtual boundary is
A point α at which a straight line that contacts the inner surface of the fixed portion 1 on the same side as the edge and the optical axis from the edge of the converging mirror 6 intersects with the front end surface of the fixed portion,
As α ′, an infrared sensor is installed in a region between the optical path K4 α farther from the converging mirror 6 than Fα and the optical path K4 α ′ farther from the converging mirror 6 than Fα ′.
As a result, the fixed portion 1 is moved between the α and the condenser mirror 6 in the optical path K.
Since it is located farther from the optical axis than 1α and K1α ', an optical system that does not receive light from the fixed portion can be obtained.

The above is described in detail below.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 28, the light passing through the optical path K2α passes through the condenser mirror 6, crosses the optical axis at F, reaches Fα, and moves away from the optical axis. Similarly, the light passing through the optical path K1α passes through the condenser mirror 6, crosses the optical axis, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 3α crosses the optical axis at the condenser mirror 6, reaches Fα, and moves away from the optical axis. The light passing through the optical path K4α crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, arrives at Fα without crossing the optical axis and then approaches the optical axis. Or go away. Thus, α
There is an area where light emitted from α does not pass at a position further from the light collecting mirror than the image point Fα. Similarly, for α ′, there is a region where light emitted from α does not pass at a position further away from the light collecting mirror than the image point Fα of α. By installing an infrared light receiving element in a region sandwiched between the optical path K4α farther from the converging mirror 6 than Fα and the optical path K4α ′ farther from the converging mirror 6 than Fα ′. An infrared sensor that does not receive infrared rays emitted from α and α ′ is obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the condensing mirror 6 is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the point of intersection of this point by the condenser mirror 6 is farther from the optical axis than Fα. Therefore, if the light from α is not received,
It does not receive light from a point farther from the optical axis than α, and therefore does not receive light from the fixed part 1. Similarly, light from a portion farther from the optical axis than the optical path K1α 'between α' and the condenser mirror 6 is light from a point larger than α 'in the same plane as α'. Be replaced. It is well known in geometrical optics that the point of intersection of this point by the condenser mirror 6 is farther from the optical axis than Fα ′.

Therefore, if light from α ′ is not received, light from a point farther from the optical axis than α ′ will not be received, and therefore no light from the fixed portion 1 will be received. As described above, the optical path K4α at a portion farther from the converging mirror 6 than Fα
And the optical path K4 at a portion farther from the focusing mirror 6 than Fα '.
If the infrared ray radiated from α and α ′ is not received by installing the infrared light receiving element 4 in the area sandwiched by α ′, the infrared ray radiated from the fixed part 1 is not automatically received. Becomes

In the following, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

[0537] The infrared light receiving element 4 is more converging mirror 6 than Fα.
Far from. At this time, equations (14) and (15) hold.

As shown in FIG. 28, since the light receiving surface is farther from the converging mirror 6 than Fα, of the optical paths from α to Fα, the light receiving surface closest to the infrared light receiving element 4 is K 4 α.
It is. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (16).

Here, as is well known in geometrical optics, r3, rα
F, LαF, rαS4, L3, and f are expressed as (1
Equations (7) and (18) are satisfied.

The equation (19) is obtained by substituting the equation (18) into the equation (16).

From the expressions (15) and (19), the condition for not receiving the light radiated from α by the infrared receiving element 4 is (2)
0).

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by a geometric relationship (21)
Equation (22) is satisfied.

By substituting the expression (22) into the expression (20), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the expression (23).

Also, from Gauss's formula, equation (24), (2
5) Formula holds.

By substituting equation (25) into equation (23), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (26).

As described above, in order to prevent the light radiated from α from being received by the infrared receiving element 4, the optical system must satisfy the condition of the expression (20), the expression (23) or the expression (26). Need to be designed. Expression (20), Expression (23),
By disposing the light receiving element 4 from the focal point of the condenser mirror 6 by L3 given by the equation (26), the infrared light radiated from the fixed portion 1 is not received by the infrared light receiving element 4 and the object to be measured is not received. , Only infrared radiation can be received by the infrared light receiving element 4, so that a measurement error due to a temperature change of the fixed portion 1 can be prevented.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIGS. 29 and 30 show an optical system of an infrared sensor according to the twenty-third embodiment of the present invention. FIG.
In 30, 6 is a condenser mirror, 4 is an infrared light receiving element,
9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to a region where light is to be received in a concave portion such as the inside of a hole, 2 is a lens aperture stop for determining an effective region of the condenser mirror 6,
α and α ′ are points where a straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to the optical axis with the edge intersects the tip of the fixed part, A is a point at the tip of the fixed part 1, and B is Points other than the tip of the fixed portion 1, F is the focal point of the condenser mirror 6, Fα and Fα ′ are α and α ′ image points by the condenser mirror 6, FA is an image point of A by the condenser mirror 6, and FB is B by focusing mirror 6
K1α is an optical path of light (marginal ray) which travels from F to α through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis and travels to Fα. The optical path of light traveling parallel and passing through the focal point F and reaching Fα, K3α
Is the optical path of the light that reaches Fα from α through the center of the condenser mirror 6, and K4 α reaches Fα from α through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis. The optical path of the light (marginal ray), K1A, passes through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis from A and passes through FA.
K2A is an optical path of light (marginal ray) traveling in parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is an optical path from A passing through the center of the focusing mirror 6 from A. F
K4A is an optical path of light reaching A, K1A is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from A to reach FA, and K1B is an optical path from B. An optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the axis and traveling to FB, K2B
Is the optical path of light traveling parallel to the optical axis from B and passing through the focal point F to reach FB, K3B is the optical path of light passing from B through the center of the focusing mirror 6 to reach FB, and K4B is from B The optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis and reaching FB, FαS1 is the intersection of the optical path K1α with the light receiving surface, and FAS1 is the optical path K1A. The intersection point with the light receiving surface, FBS1 is the intersection point between the optical path K1B and the sensor surface, r
α is the opening radius of the fixed part 1 at the point α, rA is the opening radius of the fixed part 1 at the point A, rB is the opening radius of the fixed part 1 at the point B,
r2 is the aperture radius of the lens aperture stop 2, and r3 α1 is the optical path K
1α is the distance from the optical axis of the condenser mirror 6, r3A1 is the distance of the optical path K1A from the optical axis of the condenser mirror 6, r3B
1 is the distance of the optical path K1B from the optical axis of the condenser mirror 6,
rs is the radius of the infrared light receiving element 4, rαS1 is the distance between FαS1 and the optical axis, rAS1 is the distance between FAS1 and the optical axis, and rBS1 is FBS1.
RAF is the distance between FA and the optical axis, and rBF is F
The distance between B and the optical axis, L α is the distance from α to the lens aperture stop 2, LA is the distance from A to the lens aperture stop 2, LB
Is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the condenser mirror 6, f is the focal length of the condenser mirror 6, L3 is the distance from F to the infrared light receiving element 4, LαF Is the distance from the condenser mirror 6 to Fα, LAF is the distance from the condenser mirror 6 to FA, and LBF is the condenser mirror 6
Is the distance from to FB.

An optical design condition is determined so that light emitted from any point of the fixed portion is not received by the infrared light receiving element 4. For this purpose, the light radiated from α is imagined, and a design condition for preventing the light from being received by the infrared light receiving element 4 is determined. A condition that light is not received by the element 4 is added.

First, the position of the infrared light receiving element 4 is determined as follows so as not to receive the infrared light radiated from α of the fixed portion 1.

The light radiated from α has optical paths K 1 α and K 2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 29, the light passing through the optical path K2α passes through the condenser mirror 6, crosses the optical axis at F, and reaches Fα while leaving the optical axis. Similarly, light passing through the optical path K1α passes through the condenser mirror 6, crosses the optical axis, and then reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the condenser mirror 6 and then reaches Fα while leaving the optical axis. Optical path K
4 The light passing through α crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, the F
reaches α. As described above, there is a region where light emitted from α does not pass at a position farther from the condenser mirror than the point where the optical path K1α intersects with the optical axis and closer to the condenser mirror 6 than Fα. By locating the infrared light receiving element 4 at a position farther from the converging mirror 6 than at the point where the optical path K1α intersects with the optical axis and closer to the converging mirror 6 than Fα,
An infrared sensor that does not receive light emitted from α is obtained. Hereinafter, L3 is obtained.

[0556] The infrared light receiving element 4 is more converging mirror 6 than Fα.
Close to. At this time, equations (27) and (28) hold.

As shown in FIG. 29, the light receiving surface has an optical path K1 α
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (29).

Here, as is well known in geometrical optics, r3 α1,
rαF, LαF, rαS1, L3, and f satisfy Equations (30) and (31) as geometric relationships.

The equation (32) is obtained by substituting the equation (31) into the equation (29).

From the equations (28) and (32), the condition for not receiving the light radiated from α by the infrared receiving element 4 is (3)
3) Equation is obtained.

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (34)
Equation (35) is satisfied.

By substituting the equation (35) into the equation (33), the condition for preventing the infrared light receiving element 4 from receiving the light radiated from α becomes the following equation (36).

Also, from Gauss's formula, equation (37), (3
8) Equation holds.

By substituting equation (38) into equation (36), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (39).

As is well known in geometrical optics, r 2, r
α, Lα, r3α1 and L2 are expressed as geometric relationships (40)
Equation (41) is satisfied.

By substituting equation (41) into equation (39), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (42).

As described above, in order for the light radiated from α at the tip of the fixed portion 1 not to be received by the infrared light receiving element 4, (3
It is necessary to design the optical system so as to satisfy the condition of the expression (3), the expression (36), the expression (39), or the expression (42).

The infrared sensor whose optical system is designed so as to satisfy the condition of the expression (33), the expression (36), the expression (39), or the expression (42) emits light from a point other than α of the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, a condition for not receiving light from A and B is determined below with reference to FIG.

First, a condition for not receiving the light radiated from A is determined. As shown in FIG. 30, the light path closest to the infrared light receiving element 4 on the light receiving surface is K1A among the light paths from A to FA. In the case of a fixed portion shape in which A and α do not match, K1A is shielded from light by the fixed portion 1 between A and the lens aperture stop 2, and each optical path does not approach the infrared light receiving element 4 closer to the infrared light receiving element 4 than K1A. Therefore, the condition that the light radiated from A is not received by the infrared light receiving element 4 is that the distance rAS1 between the optical axis and FAS1, which is the intersection of K1A and the light receiving surface, is larger than rs. That is, if the expression (43) is satisfied, the light radiated from A is not received by the infrared light receiving element 4.

As is well known in geometrical optics, r3A1, r3
AF, LA, rAs1, f, and L3 are represented as geometric relationships (44)
Equation (45) is satisfied.

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (46) as a geometric relationship.
7) Formula is satisfied.

By substituting equation (47) into equation (45), equation (48) is obtained.

Also, from Gauss's formula, equation (49), (5
Equation (0) holds.

By substituting equation (50) into equation (48), equation (51) is obtained.

As is well known in geometrical optics, r2, rA
, LA, r3A1 and L2 are expressed by the following equation (52) as a geometric relationship.
Formula (53) is satisfied.

By substituting equation (53) into equation (51), equation (54) is obtained.

Similarly to rAS1, rαS1 is as shown in equation (55).

A is the point at the tip of the fixed part, and α is the point at which the straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (5
Equation 6) holds, and the distance from the optical axis to A is α from the optical axis.
(57) holds.

By substituting equation (56) into equation (55), equation (58) is obtained.

Since rαS1 satisfies the relationship of equation (29),
If rAS1 is larger than rαS1, that is, if equation (59) is satisfied, rAS1 automatically satisfies the relation of equation (43).

(55) By substituting equation (58) into equation (59), equation (60) is obtained.

From equation (57), equation (60) becomes equation (61).

As described above, in order to prevent the light radiated from the virtual point α and the tip point A of the fixed portion 1 from being received by the infrared light receiving element 4, the expression (33), the expression (36), or the expression (3)
The condition of the expression 9) or the expression (42) is satisfied, and (6)
It is necessary to satisfy the expression 1).

Next, a condition for not receiving light emitted from B will be determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. Since B is a point other than the tip of the fixed portion, B is closer to the condenser mirror 6 than the point α on the tip surface of the fixed portion. Therefore, as is well known in geometrical optics, the image point FB is farther from the light collecting mirror 6 than the image point Fα of the light collecting mirror 6. That is, equation (62) holds.

The distance from the light collecting mirror 6 to the light receiving surface is smaller than the distance from the light collecting mirror 6 to Fα. Therefore, from the equation (62), the distance from the light collecting mirror 6 to the light receiving surface is smaller than the distance from the light collecting mirror 6 to FB. At this time, as shown in FIG. 30, the light path closest to the infrared light receiving element 4 on the light receiving surface is K1B among the optical paths from B to FB. In order to prevent the light radiated from B from being received by the infrared light receiving element 4, FBS1 which is the intersection of K1B and the light receiving surface is used.
The distance rBS1 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (63) needs to be satisfied.

As is well known in geometrical optics, r3B1, r3
BF, LB, rBs1, f and L3 are expressed as a geometric relation (64)
Equation (65) is satisfied.

Further, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (66) as a geometric relationship.
7) Formula is satisfied.

By substituting equation (67) into equation (65), equation (68) is obtained.

From Gauss's formula, equation (69), (7
Equation (0) holds.

By substituting equation (70) into equation (68), equation (71) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are expressed by the following equation (72) as a geometric relationship.
Formula (73) is satisfied.

By substituting equation (73) into equation (71), equation (74) is obtained.

Similarly to rBS1, rαS1 is as shown in equation (75).

Since rαS1 satisfies the relationship of equation (29),
If rBS1 is larger than rαS1, that is, if equation (76) is satisfied, rBS1 automatically satisfies the relation of equation (63).

(74) By substituting equation (75) into equation (76), equation (77) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (78) and (79) are established for Lα and LB.

An infrared sensor that satisfies the condition of the expression (33), the expression (36), the expression (39), or the expression (42), and the optical system designed to satisfy the expression (61), In order not to receive the radiated light from points other than the surface, the relationship of the equation (77) needs to be established for each point B.

Therefore, it is necessary to satisfy Expression (80) by considering the relationship between Expressions (61) and (79).

As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared receiving element 4, the expression (33), the expression (36), the expression (39), or the expression (42) And the condition (61) is satisfied, and (8)
It is necessary to satisfy the expression 1).

The infrared light receiving element 4 is provided away from the focal plane of the condenser mirror 6 by an amount given by the expression (33), (36), (39), or (42).
In addition, by adopting an optical design that satisfies the formulas (61) and (81), the infrared light radiated from the object to be measured is received only by the infrared light , It is possible to prevent a measurement error caused by a temperature change of the fixed portion.

[0601] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIGS. 31, 32, and 33 show an optical system of an infrared sensor according to a twenty-fourth embodiment of the present invention. In FIGS. 31, 32 and 33, 6 is a condensing mirror, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving region such as the inside of a hole in a concave portion. Reference numeral 2 denotes a lens aperture stop for determining the effective area of the condenser mirror 6, and α and α 'are fixed lines that are in contact with the edge of the lens aperture stop 2 and the inner surface of the fixed portion 1 on the same side with respect to this edge and the optical axis. A is a point at the tip of the fixed part 1, A is a point other than the tip of the fixed part 1, F is a focal point of the condenser mirror 6,
α and Fα ′ are the image points of α and α ′ by the condenser mirror 6, FA is the image point of A by the condenser mirror 6, FB is the image point of B by the condenser mirror 6, and K1 α is the optical axis from α. The optical path of the light (marginal ray) that passes through the edge of the opening of the lens aperture stop 2 on the same side and travels to Fα, K2α travels from α in parallel with the optical axis, passes through the focal point F, and passes through Fα. K3α is the optical path of the light from α that passes through the center of the condenser mirror 6 and reaches Fα, and K4α is the opening of the lens aperture stop 2 on the opposite side of α from the optical axis. Through the edge of
K1A is the optical path of the light (marginal ray) that reaches from the point A to the optical axis, passing through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis and traveling to FA.
K2A travels from A in parallel with the optical axis, passes through the focal point F, and
K3A is the optical path of light from A passing through the center of the condenser mirror 6 to reach FA, and K4A is the edge of the aperture of the lens aperture stop 2 on the opposite side of A from the optical axis. Path of light (marginal ray) that passes through and reaches FA, K1B
Is a light (marginal ray) traveling from B to FB through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis.
K2B is an optical path of light traveling parallel to the optical axis from B and passing through the focal point F to reach FB; K3B is an optical path of light passing from B through the center of the focusing mirror 6 and reaching FB; K4B is B
, The optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the opposite side with respect to the optical axis and reaching FB, FαS4 is the intersection of the optical path K4α with the light receiving surface, and FAS4 is the optical path K4A. FBS4 is the intersection of the optical path K4B and the sensor surface, FαS1 is the intersection of the optical path K1A and the light receiving surface, FBS1
Is the intersection of the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the point α, rA is the opening radius of the fixed part 1 at the point A, r
B is the aperture radius of the fixed portion 1 at the point B, r2 is the aperture radius of the lens aperture stop 2, and r3 α4 is the condenser mirror 6 of the optical path K4 α.
, R3A4 is the distance of the optical path K4A from the optical axis in the collecting mirror 6, r3B4 is the distance of the optical path K4B from the optical axis in the collecting mirror 6, and r3 α1 is the optical path K1.
α is the distance from the optical axis of the condenser mirror 6, r3B1 is the distance of the optical path K1B from the optical axis of the condenser mirror 6, rs is the radius of the infrared light receiving element 4, rαS4 is the distance between FαS4 and the optical axis,
rAS4 is the distance between FAS4 and the optical axis, rBS4 is the distance between FBS4 and the optical axis, rαS1 is the distance between FαS1 and the optical axis, and rBS1 is FBS.
The distance between BS1 and the optical axis, rαF is the distance between Fα and the optical axis, r
AF is the distance between FA and the optical axis, rBF is the distance between FB and the optical axis,
L α is the distance from α to the lens aperture stop 2, LA is the distance from A to the lens aperture stop 2, LB is the distance from B to the lens aperture stop 2, and L2 is the distance from the lens aperture stop 2 to the condenser mirror 6. Distance, f is the focal length of the condenser mirror 6, L3
Is the distance from F to the infrared light receiving element 4, LαF is the distance from the condenser mirror 6 to Fα, and LAF is the distance from the condenser mirror 6 to FA.
LBF is the distance from the condenser mirror 6 to FB.

The infrared light emitted from α on the fixed part 1 is assumed, and the position of the infrared light receiving element 4 is determined as described below so as not to receive this light.

The light radiated from α has optical paths K 1 α and K 2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 31, the light passing through the optical path K2α passes through the condenser mirror 6, crosses the optical axis at F, reaches Fα, and moves away from the optical axis. Similarly, the light passing through the optical path K1α passes through the condenser mirror 6, crosses the optical axis, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 3α crosses the optical axis at the condenser mirror 6, reaches Fα, and moves away from the optical axis. The light passing through the optical path K4α crosses the optical axis and passes through the converging mirror 6, and after passing through the converging mirror 6, arrives at Fα without crossing the optical axis and then approaches the optical axis. Or go away. Thus, α
There is an area where light emitted from α does not pass at a position further from the light collecting mirror than the image point Fα. By installing the infrared light receiving element 4 at a position more distant from the light collecting mirror 6 than the image point Fα of α, an infrared sensor that does not receive light emitted from α can be obtained. Hereinafter, the distance L3 from the focal point of the condenser mirror 6 to the light receiving surface will be determined.

[0605] The infrared light receiving element 4 is more converging mirror 6 than Fα.
Far from. At this time, equations (82) and (83) hold.

As shown in FIG. 31, since the light receiving surface is farther from the converging mirror 6 than Fα, of the light paths from α to Fα, the light receiving surface closest to the infrared light receiving element 4 is K4α.
It is. Therefore, in order for the infrared light receiving element 4 not to receive the light from α, it is necessary to satisfy the expression (84).

Here, as is well known in geometrical optics, r3α4,
rαF, LαF, rαS4, L3, and f satisfy the equations (85) and (86) as geometric relationships.

The equation (87) is obtained by substituting the equation (86) into the equation (84).

From the equations (83) and (87), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (8
8)

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (89)
Equation (90) is satisfied.

By substituting the expression (90) into the expression (88), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the expression (91).

Also, from Gauss's formula, equation (92), (9
3) Equation holds.

By substituting equation (93) into equation (91), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (94).

As is well known in geometrical optics, r2, r
α, Lα, r3α4, L2 are expressed as a geometric relationship (95)
Equation (96) is satisfied.

By substituting the expression (96) into the expression (94), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the expression (97).

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to design an optical system to satisfy the conditions.

The infrared sensor whose optical system is designed to satisfy the condition of the expression (88), the expression (91), the expression (94), or the expression (97) emits light from a point other than α on the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, conditions for not receiving light from A and B are determined below with reference to FIGS.

First, referring to FIG. 32, a condition for not receiving light emitted from A is determined. Since the distance from A to the condenser mirror 6 and the distance from α to the condenser mirror 6 are equal, the image points F of A and α by the condenser mirror 6 are well known in geometrical optics.
A and Fα are formed in the same plane. Therefore, the light receiving surface is F
Since it is farther from the converging mirror 6 than α, the light receiving surface is farther than FA. Therefore, as shown in FIG.
K4A is the light path closest to the infrared light receiving element 4 on the light receiving surface among the optical paths up to A. In order to prevent the light emitted from A from being received by the infrared light receiving element 4, the distance rAS4 between the optical axis and FAS4, which is the intersection of K4A and the light receiving surface, needs to be larger than rs. That is, equation (98) needs to be satisfied.

As is well known in geometrical optics, r3A4, r3
AF, LAF, rAs4, f, and L3 are expressed as a geometric relationship (99)
Equation (100) is satisfied.

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (101) as a geometric relationship.
02) is satisfied.

By substituting equation (102) into equation (100), equation (103) is obtained.

Also, from Gauss's formula, equation (104)
Equation (105) holds.

By substituting equation (105) into equation (103), equation (106) is obtained.

As is well known in geometrical optics, r2, rA
, LA, r3A4, and L2 are expressed as geometric relationships (107)
Equation (108) is satisfied.

By substituting equation (108) into equation (106), equation (109) is obtained.

Similarly to rAS4, rαS4 is as shown in equation (110).

Since rαS4 satisfies the relationship of equation (84),
If equation (111) is satisfied, rAS4 automatically satisfies the relation of equation (98).

(109) By substituting equation (110) into equation (111), equation (112) is obtained.

A is the point at the tip of the fixed part, and α is the point at which the straight line that contacts the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (1
Expression 13) holds, and the distance from the optical axis to A is equal to or greater than the distance from the optical axis to α, and Expression (114) holds.

From the expression (113), the condition of the expression (112) is as shown in the expression (115).

From the expression (114), the condition of the expression (115) is as shown in the expressions (116) and (117).

The infrared sensor designed with the optical constants and each positional relationship so as to satisfy the condition of the expression (88), the expression (91), the expression (94), or the expression (97) is used. In order not to receive the radiated light, the optical design needs to satisfy the condition of the expression (117).

Next, a condition for not receiving the light radiated from B is determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. B to FB
The light path closest to the infrared light receiving element 4 on the light receiving surface among the respective optical paths up to is K4B when the image point FB is closer to the condenser mirror 6 than the light receiving surface as shown in FIG. As shown, when the image point FB is closer to the condenser mirror 6 than the light receiving surface, it is K1B.

First, as shown in FIG. 32, FB is closer to the converging mirror 6 than the light receiving surface, and therefore K4B is the light receiving surface of each optical path from B to FB that comes closest to the infrared light receiving element 4. A case is shown in which the light emitted from B is not received by the infrared light receiving element 4.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, it is necessary to use FBS4, which is the intersection of K4B and the light receiving surface.
The distance rBS4 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (118) needs to be satisfied.

As is well known in geometrical optics, r3B4, r3
BF, LBF, rBs4, f, and L3 are represented as (11
Equations 9) and (120) are satisfied.

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (121) as a geometric relationship.
22) Formula is satisfied.

By substituting equation (122) into equation (120), equation (123) is obtained.

From Gauss's formula, equation (124)
Equation (125) holds.

By substituting equation (125) into equation (123), equation (126) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B4, and L2 are expressed as geometric relationships (127)
Equation (128) is satisfied.

The equation (129) is obtained by substituting the equation (128) into the equation (126).

[0643] Similarly to rBS4, rαS4 is given by equation (130).

Since rαS4 satisfies the relationship of equation (84),
If equation (131) is satisfied, rBS4 automatically becomes (118)
This satisfies the relationship of the expression.

(129) By substituting equation (130) into equation (131), equation (132) is obtained.

Here, since α is a point on the tip end surface of the fixed part 1, the relations of the equations (133) and (134) hold for Lα and LB.

The condition of the expression (88), the expression (91), the expression (94), or the expression (97) is satisfied, and (11)
The infrared sensor designed with the optical constants and each positional relationship according to the condition of the expression 7) does not receive the light emitted from any point other than the tip of the fixed part, that is, does not receive the light emitted from any point of the fixed part. To do this, for any B (132)
It is necessary that the relationship of the expressions hold. Therefore, (13
4) In consideration of equation (117), equation (135) needs to be satisfied.

As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. Must be satisfied, the condition of expression (117) must be satisfied, and the expression (136) must be satisfied.

Next, as shown in FIG. 33, FB is farther from the converging mirror 6 than the light receiving surface, and therefore, of the respective optical paths from B to FB, the one closest to the infrared light receiving element 4 on the light receiving surface is K1B. In the case of, the condition that the light emitted from B is not received by the infrared light receiving element 4 is shown.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, FBS1 which is the intersection of K1B and the light receiving surface is used.
The distance rBS1 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (137) needs to be satisfied.

As is well known in geometrical optics, r3B1, r3
B, LB, rBs1, f, and L3 are expressed as geometric relationships (13
8) and (139) are satisfied.

As is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (140) as a geometric relationship.
41) Formula is satisfied.

The equation (142) is obtained by substituting the equation (141) into the equation (139).

Also, from Gauss's formula, equation (143)
Equation (144) holds.

[0655] By substituting equation (144) into equation (142), equation (145) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are represented as geometric relationships (146)
Equation (147) is satisfied.

[0657] By substituting equation (147) into equation (145), equation (148) is obtained.

As with rBS1, rαS1 is given by equation (149).

Here, of the respective optical paths from α to Fα, the one closest to the infrared light receiving element 4 on the light receiving surface is K4α, and the equation (150) is established.

Since rαS4 satisfies the relationship of equation (84),
If equation (151) is satisfied, rBS1 automatically becomes (137)
This satisfies the relationship of the expression.

(148) By substituting equation (149) into equation (151), equation (152) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (153) and (154) are established for Lα and LB.

An infrared sensor having an optical design that satisfies the condition of the expression (88), the expression (91), the expression (94), or the expression (97) and the expressions (117) and (136) is used. In order to not receive the light emitted from any point other than the tip end surface of the fixed portion, that is, to not receive the light emitted from any point of the fixed portion, it is necessary to set (15
2) The relationship of the expression needs to be satisfied. Therefore, (1
The expression (155) needs to be satisfied in consideration of the expressions (54) and (117).

The equations (156) and (136) are equal.
Therefore, as described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to satisfy the condition, satisfy the expression (117), and further satisfy the expression (136).

As described above, according to the present embodiment, the infrared light receiving element 4 is replaced by the expression (88), the expression (91), or the expression (9).
It is provided away from the focal point of the condenser mirror 6 by an amount given by the expression (4) or (97), and the expressions (117) and (13)
6) By using an optical design that satisfies the expression,
The infrared light from the object to be measured can be received by the infrared light receiving element 4 without receiving the infrared light emitted by the infrared light receiving element 4 from the object to be measured, thereby preventing a measurement error due to a temperature change of the fixed portion. Can be.

[0666] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIG. 34 shows an infrared sensor according to a twenty-fifth embodiment of the present invention. In FIG. 34, 7 is a reflective diffraction lens, 4 is an infrared light receiving element, 9 is a housing, A,
A 'is a point located at a boundary between a region where light reception is desired and a region where light reception is not desired; B is a point of a region where light reception is not desired; F is a focal point of the reflection type diffraction lens 6;
FA ′ is the image point of A ′ by the reflective diffraction lens 6,
FB is an image point of B by the reflection type diffraction lens 6, K1A is an optical path of a light (marginal ray) which travels to A through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis from A, K2A is the optical path of light that travels from A in parallel with the optical axis and passes through the focal point F to reach FA, K3A is the optical path of light that passes from A through the center of the reflective diffractive lens 6 and reaches FA, and K4A is the optical path of light. K1A 'is an optical path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 opposite to the optical axis from A and reaching the FA, and K1A' is a lens on the same side as A 'with respect to the optical axis. K2A 'is an optical path of light (marginal ray) which passes through the edge of the aperture of the aperture stop 2 and travels to FA'. Light that travels from A 'in parallel with the optical axis, passes through the focal point F, and reaches FA'. Light path, K3
A ′ passes through the center of the reflective diffraction lens 6 from A ′ and
K4A 'is an optical path of light reaching A', K3B is an optical path of light (marginal ray) passing through the edge of the opening of lens aperture stop 2 on the opposite side of A from the optical axis and reaching FA '. FX is the optical path of light that reaches FB from B through the center of the reflective diffraction lens 6, and FX is the intersection of the optical paths K1A and K1A '.

An optical system is designed so that only infrared rays radiated from the area to be measured are received by the infrared light receiving element.

[0669] The infrared light receiving element 4 is attached to the housing 9 so that infrared light that does not pass through the reflective diffraction lens 6 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

The light radiated from A is divided into optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 34, the light passing through the optical path K2A passes through the reflective diffraction lens 6, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, the light passing through the optical path K1A passes through the reflection type diffraction lens 6, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the reflection type diffraction lens 6, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the reflective diffraction lens 6, and after passing through the reflective diffraction lens 6, reaches the FA without crossing the optical axis. As described above, at a position farther from the reflection type diffraction lens than the point FX where the optical path K1A and the optical axis intersect, and a position closer to the reflection type diffraction lens 6 than FA,
There is an area through which the light emitted from does not pass. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The point B outside the area to receive light and in the area not to receive light is farther from the optical axis than A, so that the image point FB of B by the reflective diffraction lens 6 is farther from the optical axis than FA. This is well known. Therefore, FX and FA
By disposing an infrared light receiving element inside the triangle formed by F and FA 'so as not to receive infrared light radiated from A and A', it is possible to automatically receive no infrared light from B.

As described above, by installing the infrared light receiving element 4 inside the triangle formed by FX, FA and FA ', it is possible to receive only infrared light radiated from a region near the optical axis where light is desired to be received. An infrared sensor is obtained.

FIG. 35 shows an infrared sensor according to a twenty-sixth embodiment of the present invention. In FIG. 35, 6 is a reflective diffraction lens, 4 is an infrared light receiving element, 9 is a housing,
A 'is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of a reflective diffractive lens, and FA is an image point of A by a reflective diffractive lens 6. , FA ′ are the image points of A ′ by the reflection type diffraction lens 6,
B is an image point of B by the reflection type diffractive lens 6, K1A is an optical path of light (marginal ray) which travels to A through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis from A,
K2A travels from A in parallel with the optical axis, passes through the focal point F, and
K3A is a reflection type diffraction lens 6 from A
K4A is an optical path of light (marginal ray) passing through the center of the lens and arriving at FA through K4A, passing through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis with respect to the optical axis. , K1A 'is the optical path of the light (marginal ray) that travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side as the optical axis, and K2A' is the optical path from A 'to the optical axis. The optical path of light traveling parallel and passing through the focal point F to reach FA ', K3A'
Is the optical path of light from A 'that reaches FA' through the center of the reflective diffractive lens 6, and K4A 'is the light path from A passing through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis with respect to the optical axis. K3B is the optical path of the light (marginal ray) reaching FA ', K3B is the optical path of the light passing from the center of the reflective diffractive lens 6 to B and reaches FX, FX is the intersection of the optical paths K1A and K1A', and FY is the optical path K
This is the intersection of 4A and the optical path K4A '.

An optical system is designed such that only infrared rays radiated from the area to be measured are received by the infrared light receiving element.

[0675] The infrared light receiving element 4 is attached to the housing 9 so that infrared light that does not pass through the reflective diffraction lens 6 is not received by the infrared light receiving element 4. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

The light radiated from A is divided into optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 35, the light passing through the optical path K2A passes through the reflective diffraction lens 6, crosses the optical axis at F, reaches FA, and leaves the optical axis. Similarly, the light passing through the optical path K1A passes through the reflective diffraction lens 6, crosses the optical axis, reaches FA, and moves away from the optical axis. Optical path K3A
Passes through the reflection type diffractive lens 6 and intersects with the optical axis.
And moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the reflective diffraction lens 6, and after passing through the reflective diffractive lens 6, reaches the FA without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is a region where the light emitted from A does not pass at a position farther from the reflective diffraction lens than the image point FA of A. This region includes the optical path K4A at a portion farther from the reflection type diffraction lens 6 than FA, and the reflection type diffraction lens 6
This is an area sandwiched between the optical paths K4A 'far from the optical path K4A'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

[0679] Since B in the area outside the area where light is to be received and in the area where light is not desired to be received is farther from the optical axis than A, it is unlikely that the image point FB of B by the reflective diffraction lens 6 is farther from the optical axis than FA. As is well known. Therefore, by installing the infrared light receiving element in a region between the optical path K4A farther from the reflective diffraction lens 6 than FA and the optical path K4A 'farther from the reflective diffraction lens 6 than FA'. A,
If you do not receive the infrared radiation emitted from A ',
The configuration is such that infrared rays emitted from B are not automatically received.

As described above, the infrared light is received in the area between the optical path K4A farther from the reflective diffraction lens 6 than FA and the optical path K4A 'farther from the reflective diffraction lens 6 than FA'. By installing the element 4, an infrared sensor that receives only infrared light emitted from a light receiving area near the optical axis can be obtained.

FIG. 36 shows an infrared sensor according to a twenty-seventh embodiment of the present invention. In FIG. 36, reference numeral 6 denotes a reflection type diffraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to a region to receive light in a concave portion such as the inside of a hole, and A, A 'is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the reflection type diffraction lens, F
A is an image point of A by the reflection type diffraction lens 6, FA 'is an image point of A' by the reflection type diffraction lens 6, FB is an image point of B by the reflection type diffraction lens 6, and K1A is from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. K3A passes through the center of the reflective diffraction lens 6 from A to reach FA, and K4A passes from A through the edge of the aperture of the lens aperture stop 2 on the opposite side with respect to the optical axis. K1A 'is the optical path of the light (marginal ray) reaching FA through the light (marginal ray) which travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis. K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' is K4A 'passes through the center of the reflection type diffractive lens 6 and reaches FA', and K4A 'passes through the edge of the aperture of the lens aperture stop 2 on the opposite side of A from the optical axis and FA'. K3B is the optical path of the light (marginal ray) that reaches FB, passes through the center of the reflective diffraction lens 6 from B and reaches FB, and FX is the optical path K
It is the intersection of 1A and the optical path K1A '.

An optical system is designed such that only infrared rays radiated from a region to be measured near the optical axis are received by the infrared light receiving element.

The infrared light receiving element 4 is attached to the housing 9 and only infrared light passing through the reflection type diffraction lens 6 is
To receive light. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

The light emitted from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 36, the light passing through the optical path K2A passes through the reflection type diffractive lens 6, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, the light passing through the optical path K1A passes through the reflection type diffraction lens 6, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the reflection type diffraction lens 6, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the reflective diffraction lens 6, and after passing through the reflective diffraction lens 6, reaches the FA without crossing the optical axis. As described above, at a position farther from the reflection type diffraction lens than the point FX where the optical path K1A and the optical axis intersect, and a position closer to the reflection type diffraction lens 6 than FA,
There is an area through which the light emitted from does not pass. This region is inside the triangle formed by FX, FA and FA '. By installing the infrared light receiving element 4 inside this triangle, an infrared sensor that does not receive light emitted from A and A ′ can be obtained.

The fixed part 1 is installed so as to be farther from the optical axis than the optical paths K1A and K1A '.

The infrared rays radiated from the fixed portion 1 are replaced with light radiated from the area on the same surface as the area on which light reception is not desired. Since point B in the area not to receive light outside the area to receive light is farther from the optical axis than A,
It is well known that the image point FB of B by the reflection type diffraction lens 6 is farther from the optical axis than FA. Therefore, if an infrared light receiving element is installed inside the triangle formed by FX, FA and FA 'so as not to receive the infrared light radiated from A and A', the infrared light from B is automatically received. No configuration. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light receiving element 4 is installed inside the triangle formed by FX, FA, and FA ', and the optical path K1A,
By providing the fixing portion 1 farther from the optical axis than K1A ', the infrared sensor can be fixed and directed to an area where light reception is desired in a concave portion such as the inside of a hole, and infrared rays emitted from the fixing portion are received. An infrared sensor that receives only infrared rays radiated from an area to be received near the optical axis without receiving the light is obtained.

[0686] The housing 9 and the fixed portion 1 may be integrated.

FIG. 37 shows an infrared sensor according to a twenty-eighth embodiment of the present invention. In FIG. 37, reference numeral 6 denotes a reflection type diffraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and pointing the infrared sensor to a light receiving region, such as the inside of a hole, in a concave portion. A 'is a point located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is a focal point of the reflection type diffraction lens, F
A is an image point of A by the reflection type diffraction lens 6, FA 'is an image point of A' by the reflection type diffraction lens 6, FB is an image point of B by the reflection type diffraction lens 6, and K1A is from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. K3A passes through the center of the reflective diffraction lens 6 from A to reach FA, and K4A passes from A through the edge of the aperture of the lens aperture stop 2 on the opposite side with respect to the optical axis. K1A 'is the optical path of the light (marginal ray) reaching FA through the light (marginal ray) which travels from A' to FA 'through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis. K2A 'is an optical path of light traveling from A' in parallel with the optical axis and passing through the focal point F to reach FA ', and K3A' is K4A 'passes through the center of the reflection type diffractive lens 6 and reaches FA', and K4A 'passes through the edge of the aperture of the lens aperture stop 2 on the opposite side of A from the optical axis and FA'. K3B is the optical path of the light (marginal ray) that reaches FB, passes through the center of the reflective diffraction lens 6 from B and reaches FB, and FX is the optical path K
It is the intersection of 1A and the optical path K1A '.

An optical system is designed such that only infrared rays radiated from an area to be measured near the optical axis are received by the infrared light receiving element.

[0689] The infrared light receiving element 4 is attached to the housing 9 so that the infrared light receiving element 4 receives only infrared light passing through the reflective diffraction lens 6. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

The light radiated from A has optical paths K1A, K2A, K
It reaches the image point FA of A through 3A, K4A and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 37, the light passing through the optical path K2A passes through the reflection type diffractive lens 6, crosses the optical axis at F, reaches FA, and moves away from the optical axis. Similarly, the light passing through the optical path K1A passes through the reflective diffraction lens 6, crosses the optical axis, reaches FA, and moves away from the optical axis. Optical path K3A
Passes through the reflection type diffractive lens 6 and intersects with the optical axis.
And moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the reflective diffraction lens 6, and after passing through the reflective diffractive lens 6, reaches the FA without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is a region where the light emitted from A does not pass at a position farther from the reflective diffraction lens than the image point FA of A. This region includes the optical path K4A at a portion farther from the reflection type diffraction lens 6 than FA, and the reflection type diffraction lens 6
This is an area sandwiched between the optical paths K4A 'far from the optical path K4A'. By installing an infrared sensor in this region, an optical system that does not receive infrared rays radiated from A and A ′ can be realized.

The fixed part 1 is set so as to be farther from the optical axis than the optical paths K1A and K1A '.

The infrared rays radiated from the fixed part 1 are replaced with light radiated from a region that is not desired to be received. Since the point B in the area outside the area where light is not desired to be received is farther from the optical axis than A, the fact that the image point FB of B by the reflective diffractive lens 6 is farther from the optical axis than FA is due to geometrical optics. As is well known. Therefore, by installing the infrared light receiving element in a region between the optical path K4A farther from the reflective diffraction lens 6 than FA and the optical path K4A 'farther from the reflective diffraction lens 6 than FA'. If the infrared rays radiated from A and A ′ are not received, the configuration is such that the infrared rays radiated from B are not automatically received. That is, the configuration is such that infrared rays emitted from the fixing unit 1 are not automatically received.

As described above, the infrared light is received in the area between the optical path K4A farther from the reflective diffraction lens 6 than FA and the optical path K4A 'farther from the reflective diffraction lens 6 than FA'. By installing the element 4 and providing the fixed part 1 between the A and the reflective diffraction lens 6 farther from the optical axis than the optical paths K1A and K1A ', an infrared sensor is provided in an area where light is to be received in a concave part such as inside a hole. Can be directed in a stable state, and an infrared sensor that receives only infrared rays emitted from an area near the optical axis and desired to be received without receiving infrared rays emitted from the fixed portion can be obtained.

[0694] The housing 9 and the fixed portion 1 may be integrated.

FIG. 38 shows an infrared sensor according to the twenty-ninth embodiment of the present invention. In FIG. 38, reference numeral 6 denotes a reflection type diffraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and pointing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, α, α ′ is the fixed portion 1 on the same side of the edge of the reflection type diffraction lens 6 with respect to this edge and the optical axis.
The point at which the straight line contacting the inner surface intersects the tip surface of the fixed portion, F is the focal point of the reflective diffraction lens 6, Fα and Fα ′ are the image points of α and α ′ by the reflective diffraction lens 6, respectively, and K1 α is the optical axis from α. , The optical path of light (marginal ray) passing through the edge of the reflective diffraction lens 6 on the same side and traveling to Fα, K2α travels from α in parallel with the optical axis, passes through the focal point F, and reaches Fα. K3α is the optical path of light from α and passing through the center of the reflective diffractive lens 6 to Fα, and K4α is the optical path of the reflective diffractive lens 6 on the opposite side of α from the optical axis. The optical path of light (marginal ray) passing through and reaching Fα, K1
α ′ is the optical path of light (marginal ray) that travels from F ′ to the Fα ′ through the edge of the reflective diffraction lens 6 on the same side with respect to the optical axis, and K 2 α ′ is parallel to the optical axis from α ′. K3α 'is an optical path of light that travels through the focal point F and reaches Fα', K3α 'is an optical path of light from α' and passes through the center of the reflective diffractive lens 6 to Fα ', and K4α' is α ' Is the optical path of light (marginal ray) passing through the edge of the reflective diffraction lens 6 on the opposite side with respect to the optical axis and reaching Fα ', and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as the inner wall of a hole is designed.

[0697] The infrared light receiving element 4 is attached to the housing 9, and only infrared light passing through the reflection type diffraction lens 6 is received by the infrared light receiving element 4.
To receive light. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

In order to receive only infrared light from the object to be measured, infrared light emitted from the fixed part 1 may be prevented from being received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the edge of the reflective diffraction lens 6 on the same side as the point located at this imaginary boundary with respect to the optical axis. Light passing through (marginal rays)
The fixed part 1 is located farther from the optical axis than the optical path of
Should be installed. Therefore, the points located at the virtual boundaries are defined as points α and α ′ where a straight line that contacts the inner surface of the fixed part 1 on the same side with respect to the optical axis from the edge of the reflective diffraction lens 6 intersects the fixed part tip surface. The infrared light receiving element 4 is set inside a triangle formed by Fα, Fα ′ and FX. As a result, the fixed portion 1 moves the optical path K between α and the reflective diffraction lens 6.
Since it is located farther from the optical axis than 1α and K1α ', an optical system that does not receive light from the fixed portion can be obtained.

The above is described in detail below. The light emitted from α reaches the image point Fα of α through the optical paths K1α, K2α, K3α, K4α, and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 38, the light passing through the optical path K2α is
After passing through the reflective diffraction lens 6 and intersecting with the optical axis at F, it reaches Fα while moving away from the optical axis. Similarly, the light passing through the optical path K1α passes through the reflective diffraction lens 6, crosses the optical axis, and then reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the reflective diffraction lens 6, and then reaches Fα while leaving the optical axis. Optical path K4
The light passing through α crosses the optical axis, passes through the reflective diffraction lens 6, and after passing through the reflective diffraction lens 6, reaches Fα without crossing the optical axis. As described above, at a position farther from the reflective diffraction lens than the point FX where the optical path K1α and the optical axis intersect and closer to the reflective diffraction lens 6 than Fα, α
There is an area through which the light emitted from does not pass. Similarly, α ′ is radiated from α ′ at a position farther from the reflective diffraction lens than at the point where the optical path K1 α ′ intersects with the optical axis and closer to the reflective diffraction lens 6 than Fα ′. There is an area through which light does not pass. This Fα, F
By installing the infrared light receiving element 4 inside the triangle formed by α 'and FX, an infrared sensor that does not receive light emitted from α and α' can be obtained. Light from a portion farther from the optical axis than the optical path K1 α between α and the reflection type diffraction lens 6 is
It is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the intersection of this point with the reflection type diffraction lens 6 is farther from the optical axis than Fα. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received, and therefore no light from the fixed portion 1 will be received. Similarly,
Light from a portion farther from the optical axis than the optical path K1 α 'between α' and the reflective diffraction lens 6 is replaced with light from a point whose distance from the optical axis is larger than α 'in the same plane as α'. . It is well known in geometrical optics that the point of intersection of this point by the reflective diffraction lens 6 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, α ′
No light from a point farther from the optical axis is received, and therefore no light from the fixed part 1 is received. Thus, Fα and Fα ′
By installing the infrared light receiving element 4 inside the triangle formed by F and FX so as not to receive the infrared light radiated from α and α ', the infrared light radiated from the fixed part 1 is automatically received. No configuration.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is closer to the reflection type diffraction lens 6 than FA. At this time, equations (1) and (2) hold.

As shown in FIG. 38, the light receiving surface has an optical path K1 α
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (3).

Here, as is well known in geometrical optics, r3, rα
F, rαS1, L3, and f are expressed by the following equation (4) as a geometric relationship.
Equation (5) is satisfied.

By substituting equation (5) into equation (3), equation (6) is obtained.

From the expressions (2) and (6), the condition for not receiving the light emitted from α by the infrared light receiving element 4 is the expression (7).

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by the following equation (8) as a geometric relationship.
Equation (9) is satisfied.

By substituting the expression (9) into the expression (7), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 becomes the expression (10).

From Gauss's formula, the equation (11) and (1
2) Formula holds.

By substituting the expression (12) into the expression (11), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is the expression (13).

As described above, in order for the infrared light receiving element 4 not to receive the light radiated from α at the tip of the fixed portion 1,
It is necessary to design the optical system to satisfy the expression (7), the expression (10), or the expression (13). Equation (7), (1
0) and L3 given by equation (13).
Is displaced from the focal point of the reflection type diffraction lens 6 so that the infrared light emitted from the fixed part 1 is not received by the infrared light receiving element 4 and only the radiated light from the measured object is received by the infrared light receiving element 4.
, It is possible to prevent a measurement error due to a temperature change of the fixed unit 1.

[0711] The housing 9 and the fixed portion 1 may be integrated.

FIG. 39 shows an infrared sensor according to the thirtieth embodiment of the present invention. In FIG. 39, reference numeral 6 denotes a reflection type diffraction lens, 4 denotes an infrared light receiving element, 9 denotes a housing, 1 denotes a fixing portion for fixing and directing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, α, α ′ is the fixed portion 1 on the same side of the edge of the reflection type diffraction lens 6 with respect to this edge and the optical axis.
The point at which the straight line contacting the inner surface intersects the tip surface of the fixed portion, F is the focal point of the reflective diffraction lens 6, Fα and Fα ′ are the image points of α and α ′ by the reflective diffraction lens 6, respectively, and K1 α is the optical axis from α. , The optical path of light (marginal ray) passing through the edge of the reflective diffraction lens 6 on the same side and traveling to Fα, K2α travels from α in parallel with the optical axis, passes through the focal point F, and reaches Fα. K3α is the optical path of light from α and passing through the center of the reflective diffractive lens 6 to Fα, and K4α is the optical path of the reflective diffractive lens 6 on the opposite side of α from the optical axis. The optical path of light (marginal ray) passing through and reaching Fα, K1
α ′ is the optical path of light (marginal ray) that travels from F ′ to the Fα ′ through the edge of the reflective diffraction lens 6 on the same side with respect to the optical axis, and K 2 α ′ is parallel to the optical axis from α ′. K3α 'is an optical path of light that travels through the focal point F and reaches Fα', K3α 'is an optical path of light from α' and passes through the center of the reflective diffractive lens 6 to Fα ', and K4α' is α ' Is the optical path of light (marginal ray) passing through the edge of the reflective diffraction lens 6 on the opposite side with respect to the optical axis and reaching Fα ', and FX is the intersection of the optical path K1α with the optical axis.

An optical system designed to receive only infrared light radiated from a concave portion such as an inner wall of a hole is designed.

[0714] The infrared light receiving element 4 is attached to the housing 9, and only infrared light passing through the reflection type diffraction lens 6 is received by the infrared light receiving element 4.
To receive light. The following design is performed after a configuration is adopted in which only infrared light that has passed through the reflective diffraction lens 6 is received.

[0715] In order to receive only infrared light from the object to be measured, infrared light radiated from the fixed part 1 may be prevented from being received. Therefore, a point located at the boundary between the region where light reception is desired and the region where light reception is not desired is imagined, and from this point, the edge of the reflective diffraction lens 6 on the same side as the point located at this imaginary boundary with respect to the optical axis. Light passing through (marginal rays)
The fixed part 1 is located farther from the optical axis than the optical path of
Should be installed. Therefore, the points located at the virtual boundaries are defined as points α and α ′ where a straight line that contacts the inner surface of the fixed part 1 on the same side with respect to the optical axis from the edge of the reflective diffraction lens 6 intersects the fixed part tip surface. An infrared sensor is installed in a region between the optical path K4α farther from the reflective diffraction lens 6 than Fα and the optical path K4α ′ farther from the reflective diffraction lens 6 than Fα ′. As a result, the fixed portion 1 is located farther from the optical axis than the optical paths K1α and K1α ′ between α and the reflective diffraction lens 6, so that an optical system that does not receive light from the fixed portion is obtained. Can be

The above is described in detail below.

The light emitted from α has the optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 39, the light passing through the optical path K2α passes through the reflection type
Crosses the optical axis to reach Fα and moves away from the optical axis. Similarly, the light passing through the optical path K1α is reflected by the reflection type diffraction lens 6.
And crosses the optical axis to reach Fα and moves away from the optical axis. The light passing through the optical path K3α crosses the optical axis by the reflective diffraction lens 6, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 4α crosses the optical axis and passes through the reflective diffractive lens 6, and after passing through the reflective diffractive lens 6, reaches Fα without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is an area where the light emitted from α does not pass at a position farther from the reflective diffraction lens than the image point Fα of α. Similarly, for α ',
There is an area where light emitted from α does not pass at a position farther from the reflective diffraction lens than the image point Fα of α. An infrared light receiving element is provided in an area between the optical path K4α farther from the reflective diffraction lens 6 than Fα and the optical path K4α ′ farther from the reflective diffraction lens 6 than Fα '. Thus, an infrared sensor that does not receive infrared rays emitted from α and α ′ can be obtained. Light from a portion farther from the optical axis than the optical path K1α between α and the reflective diffraction lens 6 is
It is replaced with light from a point whose distance from the optical axis is larger than α in the same plane as α. It is well known in geometrical optics that the intersection of this point with the reflection type diffraction lens 6 is farther from the optical axis than Fα. Therefore, if light from α is not received, light from a point farther from the optical axis than α will not be received, and therefore no light from the fixed portion 1 will be received. Similarly,
Light from a portion farther from the optical axis than the optical path K1 α 'between α' and the reflective diffraction lens 6 is replaced with light from a point whose distance from the optical axis is larger than α 'in the same plane as α'. . It is well known in geometrical optics that the point of intersection of this point by the reflective diffraction lens 6 is farther from the optical axis than Fα ′. Therefore, if light from α ′ is not received, α ′
No light from a point farther from the optical axis is received, and therefore no light from the fixed part 1 is received. As described above, the optical path K4α at a portion farther from the reflection type diffraction lens 6 than Fα and Fα ′
Optical path K4 α 'farther from the reflective diffraction lens 6 than
By placing the infrared light receiving element 4 in the area between
If you do not receive infrared rays emitted from α ',
The infrared ray emitted from the fixing unit 1 is not automatically received.

Hereinafter, the position of the infrared light receiving element 4 which does not receive the light from α will be obtained.

The infrared light receiving element 4 is farther from the reflective diffraction lens 6 than Fα. At this time, equations (14) and (15) hold. As shown in FIG. 39, the light receiving surface is farther from the reflection type diffractive lens 6 than Fα, and the light receiving surface closest to the infrared light receiving element 4 among the light paths from α to Fα is K4.
α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (16).

Here, as is well known in geometrical optics, r3, rα
F, LαF, rαS4, L3, and f are expressed as (1
Equations (7) and (18) are satisfied.

By substituting equation (18) into equation (16), equation (19) is obtained.

From the expressions (15) and (19), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (2)
0).

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed by a geometric relationship (21)
Equation (22) is satisfied.

By substituting the expression (22) into the expression (20), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 becomes the expression (23).

From the Gauss's formula, equation (24), (2
5) Formula holds.

By substituting equation (25) into equation (23), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (26).

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the optical system must satisfy the condition of the expression (20), the expression (23) or the expression (26). Need to be designed. Expression (20), Expression (23),
By disposing the light receiving element 4 from the focal point of the reflection type diffraction lens 6 by L3 given by the equation (26), the infrared light emitted from the fixed portion 1 is measured without being received by the infrared light receiving element 4. Since only the radiated light from the object can be received by the infrared light receiving element 4, a measurement error due to a temperature change of the fixed portion 1 can be prevented.

Note that the housing 9 and the fixed portion 1 may be integrated.

FIGS. 40 and 41 show an optical system of an infrared sensor according to a thirty-first embodiment of the present invention. FIG.
In 41, 6 is a reflection type diffractive lens, 4 is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and pointing the infrared sensor to an area to receive light in a concave portion such as the inside of a hole, 2
Is a lens aperture stop for determining an effective area of the reflection type diffraction lens 6, and α and α 'are fixed portions which are straight lines that contact the inner surface of the fixed portion 1 on the same side as the edge and the optical axis from the edge of the lens aperture stop 2. A point intersecting with the tip surface, A is a point at the tip of the fixed part 1, B is a point other than the tip of the fixed part 1, F is a focal point of the reflective diffraction lens 6,
Fα and Fα ′ are α, respectively due to the reflective diffraction lens 6,
The image point of α ', FA is the image point of A by the reflection type diffraction lens 6, FB is the image point of B by the reflection type diffraction lens 6, K1 α
Is a light (marginal ray) traveling from α to Fα through the edge of the opening of the lens aperture stop 2 on the same side with respect to the optical axis.
K2α is an optical path of light that travels from α to be parallel to the optical axis and passes through the focal point F to reach Fα, and K3α is light that travels from α through the center of the reflective diffraction lens 6 and reaches Fα. K4α is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side from α with respect to the optical axis and reaching Fα, and K1A is a light path from A to the optical axis. An optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the same side to the FA (marginal ray), K2A travels in parallel with the optical axis from A, passes through the focal point F and reaches the FA. Light path,
K3A passes through the center of the reflection type diffractive lens 6 from A and FA
K4A is the optical path of light (marginal ray) from A to the FA that passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis and reaches FA, and K1B is the optical axis from B The light path of light (marginal ray) passing through the edge of the aperture of the lens aperture stop 2 on the same side and traveling to FB, K2B travels from B in parallel with the optical axis, passes through the focal point F, and enters FB. K3B is the optical path of the light that arrives, K3B is the optical path of the light that passes through the center of the reflective diffraction lens 6 from B and reaches FB, and K4B is the edge of the aperture of the lens aperture stop 2 on the opposite side of the optical axis from B. The optical path of the light (marginal ray) that passes through and reaches FB, Fα
S1 is the intersection between the optical path K1α and the light receiving surface, FAS1 is the intersection between the optical path K1A and the light receiving surface, FBS1 is the intersection between the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the α point, and rA is A The radius of the opening of the fixed portion 1 at the point, rB is the opening radius of the fixed portion 1 at the point B, r2 is the opening radius of the lens aperture stop 2, and r3 α1 is the optical path K1 α from the optical axis of the reflection type diffraction lens 6. Distance, r3A1 is the distance of the optical path K1A from the optical axis in the reflective diffractive lens 6, and r3B1 is the reflective diffractive lens 6 in the optical path K1B.
, The distance from the optical axis at, rs is the radius of the infrared light receiving element 4,
rαS1 is the distance between FαS1 and the optical axis, rAS1 is the distance between FAS1 and the optical axis, rBS1 is the distance between FBS1 and the optical axis, and rAF is FA
, The distance between FB and the optical axis, and L α is α
, L is the distance from A to the lens aperture stop 2, LB is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the reflective diffraction lens 6, f Is the focal length of the reflective diffraction lens 6,
L3 is the distance from F to the infrared light receiving element 4, LαF is the distance from the reflection type diffraction lens 6 to Fα, LAF is the distance from the reflection type diffraction lens 6 to FA, LBF is the distance from the reflection type diffraction lens 6 to FB. Distance.

An optical design condition is determined such that light emitted from any point of the fixed portion is not received by the infrared light receiving element 4. For this purpose, the light radiated from α is imagined, and a design condition for preventing the light from being received by the infrared light receiving element 4 is determined. A condition that light is not received by the element 4 is added.

First, the position of the infrared light receiving element 4 is determined as follows so as not to receive the infrared light radiated from α of the fixed portion 1.

The light emitted from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 40, the light passing through the optical path K2α passes through the reflection type
And crosses the optical axis, and then reaches Fα while moving away from the optical axis. Similarly, the light passing through the optical path K1α passes through the reflective diffraction lens 6, crosses the optical axis, and then reaches Fα while leaving the optical axis. The light passing through the optical path K3α crosses the optical axis by the reflection type diffraction lens 6 and then separates from the optical axis to Fα.
To reach. The light passing through the optical path K4α crosses the optical axis and passes through the reflective diffraction lens 6, and after passing through the reflective diffraction lens 6, reaches Fα without crossing the optical axis. As described above, the position which is farther from the reflection type diffraction lens than the point where the optical path K1.alpha.
At a position close to, there is a region through which light emitted from α does not pass. By arranging the infrared light receiving element 4 at a position farther from the reflection type diffraction lens 6 than the point where the optical path K1α intersects with the optical axis and closer to the reflection type diffraction lens 6 than Fα, the light is radiated from α. An infrared sensor that does not receive light is obtained. Hereinafter, L3 is obtained.

The infrared light receiving element 4 is closer to the reflection type diffraction lens 6 than Fα. At this time, equations (27) and (28) hold.

[0734] As shown in FIG. 40, the light-receiving surface has an optical path K1α.
Is between the point where the optical axis intersects with the optical axis and Fα.
The light path closest to the infrared light receiving element 4 on the light receiving surface is K1α. Therefore, in order for the light from α to not be received by the infrared light receiving element 4, it is necessary to satisfy the expression (29).

Here, as is well known in geometrical optics, r3 α1,
rαF, LαF, rαS1, L3, and f satisfy Equations (30) and (31) as geometric relationships.

By substituting equation (31) into equation (29), equation (32) is obtained.

From the equations (28) and (32), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (3)
3) Equation is obtained.

As is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (34)
Equation (35) is satisfied.

By substituting equation (35) into equation (33), the condition for preventing the light radiated from α from being received by the infrared light receiving element 4 becomes equation (36).

Also, from Gauss's formula, equation (37), (3
8) Equation holds.

By substituting equation (38) into equation (36), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (39).

As is well known in geometrical optics, r2, r
α, Lα, r3α1 and L2 are expressed as geometric relationships (40)
Equation (41) is satisfied.

By substituting equation (41) into equation (39), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is given by equation (42).

As described above, in order to prevent the light radiated from α at the tip of the fixed portion 1 from being received by the infrared light receiving element 4, (3
It is necessary to design the optical system so as to satisfy the condition of the expression (3), the expression (36), the expression (39), or the expression (42).

The infrared sensor whose optical system is designed to satisfy the condition of the expression (33), the expression (36), the expression (39) or the expression (42) emits light from a point other than α of the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, a condition for not receiving light from A and B is determined below with reference to FIG.

First, the condition for not receiving the light radiated from A is determined. As shown in FIG. 41, of the light paths from A to FA, the light path closest to the infrared light receiving element 4 on the light receiving surface is K1A. In the case of a fixed portion shape in which A and α do not match, K1A is shielded from light by the fixed portion 1 between A and the lens aperture stop 2, and each optical path does not approach the infrared light receiving element 4 closer to the infrared light receiving element 4 than K1A. Therefore, the condition that the light radiated from A is not received by the infrared light receiving element 4 is that the distance rAS1 between the optical axis and FAS1, which is the intersection of K1A and the light receiving surface, is larger than rs. That is, if the expression (43) is satisfied, the light radiated from A is not received by the infrared light receiving element 4.

Also, as is well known in geometrical optics, r3A1,
AF, LA, rAs1, f, and L3 are represented as geometric relationships (44)
Equation (45) is satisfied.

As is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (46) as a geometric relationship.
7) Formula is satisfied.

By substituting equation (47) into equation (45), equation (48) is obtained.

From the Gauss's formula, equation (49) and (5
Equation (0) holds.

By substituting equation (50) into equation (48), equation (51) is obtained.

As is well known in geometrical optics, r2, rA
, LA, r3A1 and L2 are expressed by the following equation (52) as a geometric relationship.
Formula (53) is satisfied.

By substituting equation (53) into equation (51), equation (54) is obtained.

[0753] Like rAS1, rαS1 is as shown in equation (55).

A is the point at the tip of the fixed part, and α is the point at which the straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to this edge and the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (5
Equation 6) holds, and the distance from the optical axis to A is α from the optical axis.
(57) holds.

By substituting equation (56) into equation (55), equation (58) is obtained.

Since rαS1 satisfies the relationship of equation (29),
If rAS1 is larger than rαS1, that is, if equation (59) is satisfied, rAS1 automatically satisfies the relation of equation (43).

(55) By substituting equations (58) into equation (59), equation (60) is obtained.

From the expression (57), the expression (60) becomes the expression (61).

As described above, in order to prevent the light radiated from the virtual point α and the tip point A of the fixed part 1 from being received by the infrared light receiving element 4, the expression (33), the expression (36), or the expression (3)
The condition of the expression 9) or the expression (42) is satisfied, and (6)
It is necessary to satisfy the expression 1).

Next, a condition for not receiving light emitted from B will be determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. Since B is a point other than the tip of the fixed part, B is closer to the reflective diffraction lens 6 than the point α on the tip face of the fixed part. Therefore, as is well known in geometrical optics, the image point FB is farther from the reflection type diffraction lens 6 than the image point Fα of the reflection type diffraction lens 6. That is, equation (62) holds.

[0762] The distance from the reflective diffraction lens 6 to the light receiving surface is smaller than the distance from the reflective diffraction lens 6 to Fα. Therefore, according to the equation (62), the distance from the reflection type diffraction lens 6 to the light receiving surface is smaller than the distance from the reflection type diffraction lens 6 to FB. At this time, as shown in FIG. 41, the light path closest to the infrared light receiving element 4 on the light receiving surface is K1B among the optical paths from B to FB. In order to prevent the light radiated from B from being received by the infrared light receiving element 4, the distance rBS1 between the optical axis and FBS1, which is the intersection of K1B and the light receiving surface, is r
Must be greater than s. That is, equation (63) needs to be satisfied.

As is well known in geometrical optics, r3B1,
BF, LB, rBs1, f and L3 are expressed as a geometric relation (64)
Equation (65) is satisfied.

Also, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (66) as a geometric relationship.
7) Formula is satisfied.

By substituting equation (67) into equation (65), equation (68) is obtained.

Also, from Gauss's formula, equation (69), (7
Equation (0) holds.

The equation (71) is obtained by substituting the equation (70) into the equation (68).

As is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are expressed by the following equation (72) as a geometric relationship.
Formula (73) is satisfied.

By substituting equation (73) into equation (71), equation (74) is obtained.

[0770] Similarly to rBS1, rαS1 is as shown in equation (75).

Since rαS1 satisfies the relationship of equation (29),
If rBS1 is larger than rαS1, that is, if equation (76) is satisfied, rBS1 automatically satisfies the relation of equation (63).

(74) By substituting equation (75) into equation (76), equation (77) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, the relations of equations (78) and (79) hold for Lα and LB.

The infrared sensor which satisfies the condition of the expression (33), the expression (36), the expression (39), or the expression (42) and the optical system designed so as to satisfy the expression (61) can be used at any leading edge. In order not to receive the radiated light from points other than the surface, the relationship of the equation (77) needs to be established for each point B.

Therefore, it is necessary to satisfy Expression (80) by considering the relationship between Expressions (61) and (79).

As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (33), the expression (36), the expression (39), or the expression (42) And the condition (61) is satisfied, and (8)
It is necessary to satisfy the expression 1).

The infrared light receiving element 4 is provided away from the focal plane of the reflection type diffraction lens 6 by an amount given by the expression (33), (36), (39), or (42), and (61) ) And (81), the infrared light emitted from the fixed object is not received by the infrared light receiving element 4 but only the radiated light from the measured object is received by the infrared light receiving element 4. Therefore, it is possible to prevent a measurement error caused by a temperature change of the fixed portion.

[0778] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIGS. 42, 43 and 44 show an optical system of an infrared sensor according to the 32nd embodiment of the present invention. 42, 43 and 44, 6 is a reflection type diffraction lens, 4
Is an infrared light receiving element, 9 is a housing, 1 is a fixing portion for fixing and directing the infrared sensor to a light receiving region in a concave portion such as the inside of a hole, and 2 is a device for determining an effective region of the reflection type diffraction lens 6. Α, α ′ are points where a straight line contacting the edge of the lens aperture stop 2 from the edge of the lens aperture stop 2 to the inner surface of the fixed portion 1 on the same side with respect to the optical axis intersects with the front surface of the fixed portion, and A is the tip of the fixed portion 1 Point, B is a point other than the tip of the fixed part 1, F is the focal point of the reflection type diffraction lens 6, Fα and Fα ′ are the image points of α and α ′ by the reflection type diffraction lens 6, respectively, and FA is the reflection type diffraction lens 6.
Is the image point of A, FB is the image point of B by the reflective diffraction lens 6, and K1α is the light traveling from α to Fα through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis. The optical path of (marginal ray), K2α is the optical path of light traveling parallel to the optical axis from α and passing through the focal point F and reaching Fα, and K3α is Fα passing from α and passing through the center of the reflective diffractive lens 6. K4α is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side from α with respect to the optical axis and reaching Fα, and K1A is an optical path from A. Passing through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the axis,
The optical path of the light (marginal ray) traveling to A, K2A is the optical path of the light traveling parallel to the optical axis from A and passing through the focal point F to reach FA, and K3A is passing the center of the reflective diffractive lens 6 from A. K4A is the optical path of the light that reaches FA, K4A is the optical path of the light (marginal ray) that passes through the edge of the opening of the lens aperture stop 2 on the opposite side of the optical axis from A and reaches FA, and K1B is B
K2B passes through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis and travels to FB (marginal ray). K2B travels from B in parallel with the optical axis and passes through the focal point F. K3B is the optical path of light that reaches FB from B through the center of the reflective diffractive lens 6, and K4B is the aperture of the lens aperture stop 2 on the opposite side of the optical axis from B. The optical path of the light (marginal ray) passing through the edge of the part and reaching FB, FαS4 is the intersection of the optical path K4α with the light receiving surface, FAS4 is the intersection of the optical path K4A and the light receiving surface, and FBS4 is the optical path K4B and the sensor surface. , The intersection of the optical path K1A and the light receiving surface, FBS
1 is the intersection of the optical path K1B and the sensor surface, rα is the opening radius of the fixed part 1 at the point α, rA is the opening radius of the fixed part 1 at the point A,
rB is the aperture radius of the fixed portion 1 at the point B, r2 is the aperture radius of the lens aperture stop 2, r3 .alpha.4 is the distance of the optical path K4 .alpha. from the optical axis of the reflective diffraction lens 6, and r3A4 is the reflective diffraction of the optical path K4A. R3B4 is the distance of the optical path K4B from the optical axis of the reflective diffraction lens 6, r3 α1 is the distance of the optical path K1 α from the optical axis of the reflective diffractive lens 6, and r3B1 is the distance of the optical path K1B. The distance from the optical axis in the reflective diffraction lens 6, rs is the radius of the infrared light receiving element 4, rαS4 is the distance between FαS4 and the optical axis, rAS4 is the distance between FAS4 and the optical axis, and rBS4 is the distance between FBS4 and the optical axis. Distance, rαS1
Is the distance between FαS1 and the optical axis, rBS1 is the distance between FBS1 and the optical axis, rαF is the distance between Fα and the optical axis, rAF is the distance between FA and the optical axis, rBF is the distance between FB and the optical axis, L α is the distance from α to the lens aperture stop 2, and LA is the distance from A to the lens aperture stop 2.
, LB is the distance from B to the lens aperture stop 2, L2 is the distance from the lens aperture stop 2 to the reflective diffractive lens 6, f is the focal length of the reflective diffractive lens 6, and L3 is the infrared light from F. LαF is the distance from the reflective diffractive lens 6 to Fα, LAF is the distance from the reflective diffractive lens 6 to FA, and LBF is the distance from the reflective diffractive lens 6 to FB.

[0780] The infrared light emitted from α on the fixed portion 1 is assumed, and the position of the infrared light receiving element 4 is determined as described below so as not to receive this light.

The light radiated from α has optical paths K1 α, K2
It reaches the image point Fα of α through α, K3α, K4α and the like. As is well known in geometrical optics, the image point Fα of α is formed on the opposite side of α with respect to the optical axis. As shown in FIG. 42, the light passing through the optical path K2α passes through the reflection type
Crosses the optical axis to reach Fα and moves away from the optical axis. Similarly, the light passing through the optical path K1α is reflected by the reflection type diffraction lens 6.
And crosses the optical axis to reach Fα and moves away from the optical axis. The light passing through the optical path K3α crosses the optical axis by the reflective diffraction lens 6, reaches Fα, and moves away from the optical axis. Optical path K
The light passing through 4α crosses the optical axis and passes through the reflective diffractive lens 6, and after passing through the reflective diffractive lens 6, reaches Fα without crossing the optical axis and thereafter approaches the optical axis. Or go away. As described above, there is an area where the light emitted from α does not pass at a position farther from the reflective diffraction lens than the image point Fα of α. By installing the infrared light receiving element 4 at a position farther from the reflection type diffraction lens 6 than the image point Fα of α, an infrared sensor that does not receive light emitted from α can be obtained. Hereinafter, the distance L3 from the focal point of the reflection type diffraction lens 6 to the light receiving surface is obtained.

[0782] The infrared light receiving element 4 is farther from the reflective diffraction lens 6 than Fα. At this time, equations (82) and (83) hold. As shown in FIG. 42, since the light receiving surface is farther from the reflective diffraction lens 6 than Fα, the light receiving surface closest to the infrared light receiving element 4 among the optical paths from α to Fα is K4
α. Therefore, in order for the infrared light receiving element 4 not to receive the light from α, it is necessary to satisfy the expression (84).

Here, as is well known in geometrical optics, r3 α4,
rαF, LαF, rαS4, L3, and f satisfy the equations (85) and (86) as geometric relationships.

By substituting equation (86) into equation (84), equation (87) is obtained.

From the equations (83) and (87), the condition for not receiving the light radiated from α by the infrared light receiving element 4 is (8
8)

Further, as is well known in geometrical optics, rα, L
α, L2, rαF, and LαF are expressed as a geometric relationship (89)
Equation (90) is satisfied.

[0787] By substituting the equation (90) into the equation (88), the condition for not receiving the light radiated from α by the infrared receiving element 4 becomes the equation (91).

Also, from Gauss's formula, equation (92), (9
3) Equation holds.

By substituting the expression (93) into the expression (91), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the expression (94).

As is well known in geometrical optics, r 2, r
α, Lα, r3α4, L2 are expressed as a geometric relationship (95)
Equation (96) is satisfied.

By substituting the expression (96) into the expression (94), the condition for not receiving the light radiated from α by the infrared light receiving element 4 becomes the expression (97).

As described above, in order to prevent the light radiated from α from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to design an optical system to satisfy the conditions.

The infrared sensor whose optical system is designed to satisfy the conditions of the expression (88), the expression (91), the expression (94), or the expression (97) emits light from a point other than α on the fixed portion. A condition is shown in which no light is received, that is, no light emitted from any point of the fixed portion is received. For this purpose, conditions for not receiving light from A and B will be determined below with reference to FIGS.

First, referring to FIG. 43, a condition for not receiving light emitted from A is determined. A to reflective diffractive lens 6
And the distance between α and the reflection-type diffractive lens 6 are equal, so that the image points FA and Fα of A and α by the reflection-type diffractive lens 6 are formed in the same plane as is well known in geometrical optics.
Accordingly, since the light receiving surface is farther from the reflection type diffraction lens 6 than Fα, the light receiving surface is farther than FA. Therefore, as shown in FIG. 43, the light path closest to the infrared light receiving element 4 on the light receiving surface among the light paths from A to FA is K4A. A
In order not to receive the light radiated from the infrared light receiving element 4, the distance rAS4 between the optical axis and FAS4, which is the intersection point between K4A and the light receiving surface, needs to be larger than rs.

That is, the expression (98) needs to be satisfied.

As is well known in geometrical optics, r3A4, r3
AF, LAF, rAs4, f, and L3 are expressed as a geometric relationship (99)
Equation (100) is satisfied.

Also, as is well known in geometrical optics, rA, LA,
L2, rAF, and LAF are expressed by the following equation (101) as a geometric relationship.
02) is satisfied.

By substituting equation (102) into equation (100), equation (103) is obtained.

From Gauss's formula, equation (104),
Equation (105) holds.

The equation (106) is obtained by substituting the equation (105) into the equation (103).

As is well known in geometrical optics, r2, rA
, LA, r3A4, and L2 are expressed as geometric relationships (107)
Equation (108) is satisfied.

By substituting equation (108) into equation (106), equation (109) is obtained.

[0813] Like rAS4, rαS4 is given by equation (110).

Since rαS4 satisfies the relationship of equation (84),
If equation (111) is satisfied, rAS4 automatically satisfies the relation of equation (98).

(109) By substituting equation (110) into equation (111), equation (112) is obtained.

A is the point at the tip of the fixed part, and α is the point at which the straight line contacting the edge of the lens aperture stop 2 and the inner surface of the fixed part 1 on the same side with respect to the optical axis intersects the tip of the fixed part. ,
The distances from the lens aperture stop 2 to A and α are equal (1
Expression 13) holds, and the distance from the optical axis to A is equal to or greater than the distance from the optical axis to α, and Expression (114) holds.

From the expression (113), the condition of the expression (112) is as shown in the expression (115).

From the expression (114), the conditions of the expression (115) are as shown in the expressions (116) and (117).

An infrared sensor designed with optical constants and respective positional relationships so as to satisfy the conditions of the expression (88), the expression (91), the expression (94), or the expression (97) is used. In order not to receive the radiated light, the optical design needs to satisfy the condition of the expression (117).

Next, a condition for not receiving the light emitted from B is determined. The light emitted from B is K1B, K2B, K3B,
It reaches the image point FB of B through K4B and the like. B to FB
The light path closest to the infrared light receiving element 4 on the light receiving surface is K4B when the image point FB is closer to the reflective diffraction lens 6 than the light receiving surface as shown in FIG.
When the image point FB is closer to the reflection type diffraction lens 6 than the light receiving surface as shown in FIG.

First, as shown in FIG. 43, FB is closer to the reflection type diffractive lens 6 than the light receiving surface.
In the case where K4B is the light receiving surface closest to the infrared light receiving element 4 among the light paths up to K4B, the conditions under which the light emitted from B is not received by the infrared light receiving element 4 are shown.

In order for the infrared light receiving element 4 not to receive the light radiated from B, it is necessary to use the FBS4 at the intersection of K4B and the light receiving surface.
The distance rBS4 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (118) needs to be satisfied.

Also, as is well known in geometrical optics, r3B4, r3
BF, LBF, rBs4, f, and L3 are represented as (11
Equations 9) and (120) are satisfied.

Also, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (121) as a geometric relationship.
22) Formula is satisfied.

By substituting equation (122) into equation (120), equation (123) is obtained.

Also, from Gauss's formula, equation (124)
Equation (125) holds.

By substituting equation (125) for equation (123), equation (126) is obtained.

As is well known in geometrical optics, r2, rB
, LB, r3B4, and L2 are expressed as geometric relationships (127)
Equation (128) is satisfied.

By substituting equation (128) into equation (126), equation (129) is obtained.

[0820] Similarly to rBS4, rαS4 is given by equation (130).

Since rαS4 satisfies the relationship of equation (84),
If equation (131) is satisfied, rBS4 automatically becomes (118)
This satisfies the relationship of the expression.

(129) By substituting equation (130) into equation (131), equation (132) is obtained.

Here, since α is a point on the tip end surface of the fixed part 1, the relations of the equations (133) and (134) are established for Lα and LB.

The conditions of Expression (88), Expression (91), Expression (94), or Expression (97) are satisfied, and (11)
The infrared sensor designed with the optical constants and each positional relationship according to the condition of the expression 7) does not receive the light emitted from any point other than the tip of the fixed part, that is, does not receive the light emitted from any point of the fixed part. To do this, for any B (132)
It is necessary that the relationship of the expressions hold. Therefore, (13
4) In consideration of equation (117), equation (135) needs to be satisfied.

As described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. Must be satisfied, the condition of expression (117) must be satisfied, and the expression (136) must be satisfied.

Next, as shown in FIG. 44, FB is farther from the reflection type diffractive lens 6 than the light receiving surface, and therefore, among the optical paths from B to FB, the one closest to the infrared light receiving element 4 in the light receiving surface. In the case of K1B, a condition that light emitted from B is not received by the infrared light receiving element 4 is shown.

In order to prevent the light radiated from B from being received by the infrared light receiving element 4, it is necessary to set FBS1 at the intersection of K1B and the light receiving surface.
The distance rBS1 between the optical axis and the optical axis needs to be larger than rs.
That is, equation (137) needs to be satisfied.

As is well known in geometrical optics, r3B1,
B, LB, rBs1, f, and L3 are expressed as geometric relationships (13
8) and (139) are satisfied.

Also, as is well known in geometrical optics, rB, LB,
L2, rBF, and LBF are expressed by the following equation (140) as a geometric relationship.
41) Formula is satisfied.

By substituting equation (141) into equation (139), equation (142) is obtained.

Also, from Gauss's formula, equation (143)
Equation (144) holds.

By substituting equation (144) into equation (142), equation (145) is obtained.

Also, as is well known in geometrical optics, r2, rB
, LB, r3B1 and L2 are represented as geometric relationships (146)
Equation (147) is satisfied.

By substituting equation (147) into equation (145), equation (148) is obtained.

[0832] Like rBS1, rαS1 is given by equation (149).

Here, of the respective optical paths from α to Fα, the one closest to the infrared light receiving element 4 on the light receiving surface is K4α, and the equation (150) is established.

Since rαS4 satisfies the relationship of equation (84),
If equation (151) is satisfied, rBS1 automatically becomes (137)
This satisfies the relationship of the expression.

(148) By substituting equation (149) into equation (151), equation (152) is obtained.

Here, since α is a point on the tip end surface of the fixed portion 1, Lα and LB satisfy the relations of equations (153) and (154).

An infrared sensor having an optical design that satisfies the condition of the expression (88), the expression (91), the expression (94), or the expression (97) and the expressions (117) and (136) is used. In order to not receive the light emitted from any point other than the tip end surface of the fixed portion, that is, to not receive the light emitted from any point of the fixed portion, it is necessary to set (15
2) The relationship of the expression needs to be satisfied. Therefore, (1
The expression (155) needs to be satisfied in consideration of the expressions (54) and (117).

The equations (156) and (136) are equal.
Therefore, as described above, in order to prevent the light radiated from the fixed portion 1 from being received by the infrared light receiving element 4, the expression (88), the expression (91), the expression (94), or the expression (97) is used. It is necessary to satisfy the condition, satisfy the expression (117), and further satisfy the expression (136).

As described above, according to the present embodiment, the infrared light receiving element 4 is replaced by the expression (88), the expression (91) or the expression (9).
By providing an optical design that is provided away from the focal point of the reflective diffraction lens 6 by an amount given by the expression 4) or (97) and that satisfies the expressions (117) and (136), the radiation from the fixed unit 1 is obtained. Since only infrared radiation from the object to be measured can be received by the infrared light receiving element 4 without receiving infrared light by the infrared light receiving element 4, a measurement error due to a temperature change of the fixed portion can be prevented.

[0843] The housing 9, the fixed portion 1, and the lens aperture stop 2 may be integrated.

FIG. 47 shows an optical sensor according to the thirty-third embodiment of the present invention. The optical sensor includes an infrared sensor that receives and detects the infrared light and the far-infrared light described above, but also includes a sensor that receives and detects visible light and ultraviolet light. In FIG. 1, 3 is a refraction lens, 8 is a light receiving element, 9 is a housing, A and A 'are points located at the boundary between a region where light reception is desired and a region where light reception is not desired, B is a point of a region where light reception is not desired, F is the focal point of the refractive lens, FA is the image point of A by the refractive lens 3, FA 'is the image point of A' by the refractive lens 3, FB is the image point of B by the refractive lens 3, K1A
Is a light (marginal ray) traveling from A to FA through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis.
K2A is an optical path of light traveling from A to the optical axis and traveling through the focal point F to reach FA, K3A is an optical path of light from A passing through the center of the refractive lens 3 to reach FA, and K4A is Is A
K1A 'is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis and arriving at FA; K2A 'is an optical path of light (marginal ray) which passes through the edge of the opening of the aperture 2 and travels to FA'. Light path, K3A '
Is the optical path of light from A 'to reach FA' through the center of the refracting lens 3, and K4A 'is FA' passing through the edge of the opening of the lens aperture stop 2 on the opposite side of A from the optical axis. K3B is the refracting lens 3 from B
Is the optical path of the light that reaches the FB through the center of the optical path, and FX is the intersection of the optical paths K1A and K1A '.

[0845] An optical system is designed such that only light emitted or reflected from the region to be measured is received by the light receiving element.

[0846] The light receiving element 8 is mounted on the housing 9 so that light that does not pass through the refractive lens 3 is not received by the light receiving element 8. The following design is performed after the configuration is such that only light passing through the refraction lens 3 is received. The light emitted from A is the optical path K1
A reaches the image point FA of A through A, K2A, K3A, K4A, and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 1, the light passing through the optical path K2A passes through the refraction lens 3, crosses the optical axis at F, and then reaches FA while leaving the optical axis. Similarly, light passing through the optical path K1A passes through the refraction lens 3, crosses the optical axis, and then reaches FA while leaving the optical axis. The light passing through the optical path K3A crosses the optical axis by the refraction lens 3, and then reaches FA while leaving the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refraction lens 3, and after passing through the refraction lens 3, reaches the FA without crossing the optical axis. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the point FX where the optical path K1A intersects the optical axis and closer to the refraction lens 3 than FA. This region is inside the triangle formed by FX, FA and FA '. The light receiving element 8 is located inside the triangle.
Is provided, an optical sensor that does not receive light emitted from A and A ′ can be obtained.

[0847] The point B outside the area to receive light and in the area not to receive light is farther from the optical axis than A, so that the image point FB of B by the refracting lens 3 is farther from the optical axis than FA. As is well known. Therefore, FX, FA and FA '
If a light-receiving element is arranged inside the triangle formed by the light-receiving element so that light emitted or reflected from A and A 'is not received, light from B is not automatically received.

As described above, by installing the light receiving element 8 inside the triangle formed by FX, FA and FA ',
An optical sensor that receives only light emitted or reflected from a region near the optical axis that is desired to be received can be obtained.

FIG. 48 shows an optical sensor according to a thirty-fourth embodiment of the present invention. The optical sensor includes an infrared sensor that receives and detects the infrared light and the far-infrared light described above, but also includes a sensor that receives and detects visible light and ultraviolet light. In FIG. 2, 3 is a refraction lens, 4 is a light receiving element, 9 is a housing, A and A 'are points located at a boundary between a region to receive light and a region not to receive light, B is a point in a region not to receive light, F is the focal point of the refractive lens, FA is the image point of A by the refractive lens 3, FA 'is the image point of A' by the refractive lens 3, FB is the image point of B by the refractive lens 3, K1A
Is a light (marginal ray) traveling from A to FA through the edge of the aperture of the lens aperture stop 2 on the same side with respect to the optical axis.
K2A is an optical path of light traveling from A to the optical axis and traveling through the focal point F to reach FA, K3A is an optical path of light from A passing through the center of the refractive lens 3 to reach FA, and K4A is Is A
K1A 'is an optical path of light (marginal ray) passing through the edge of the opening of the lens aperture stop 2 on the opposite side with respect to the optical axis and arriving at FA; K2A 'is an optical path of light (marginal ray) which passes through the edge of the opening of the aperture 2 and travels to FA'. Light path, K3A '
Is the optical path of light from A 'to reach FA' through the center of the refracting lens 3, and K4A 'is FA' passing through the edge of the opening of the lens aperture stop 2 on the opposite side of A from the optical axis. K3B is the refracting lens 3 from B
The optical path of light reaching the FB after passing through the center of the optical path, FX is the intersection of the optical paths K1A and K1A ', and FY is the optical path K4A and the optical path K4A'.
Is the intersection of

[0850] An optical system is designed such that only light emitted or reflected from the region to be measured is received by the light receiving element.

[0851] The light receiving element 8 is mounted on the housing 9 so that light not passing through the refractive lens 3 is not received by the light receiving element 8. The following design is performed after the configuration is such that only light passing through the refraction lens 3 is received. The light emitted from A is the optical path K1
A reaches the image point FA of A through A, K2A, K3A, K4A, and the like. As is well known in geometrical optics, the image point FA of A is formed on the opposite side of A with respect to the optical axis. As shown in FIG. 2, light passing through the optical path K2A passes through the refracting lens 3, crosses the optical axis at F, reaches FA, and leaves the optical axis. Similarly, light passing through the optical path K1A passes through the refraction lens 3, crosses the optical axis, reaches FA, and moves away from the optical axis. Optical path K3A
Passes through the refracting lens 3 and intersects the optical axis, reaches FA, and moves away from the optical axis. The light passing through the optical path K4A crosses the optical axis and passes through the refracting lens 3, and after passing through the refracting lens 3, reaches the FA without crossing the optical axis, and thereafter approaches or moves away from the optical axis. Go. As described above, there is a region where the light emitted from A does not pass at a position farther from the refraction lens than the image point FA of A. This region is a region sandwiched between an optical path K4A at a portion farther from the refraction lens 3 than FA and an optical path K4A 'at a portion farther from the refraction lens 3 than FA'. By installing an optical sensor in this area, A,
An optical system that does not receive light rays emitted from A ′ can be realized.

It is well known that B in the region outside the region where light is to be received and not desired to be received is farther from the optical axis than A, so that the image point FB of B by the refracting lens 3 is farther from the optical axis than FA. It is on the street. Therefore, the optical path K4A at a portion farther from the refracting lens 3 than FA and the refracting lens 3 than FA '.
If a light-receiving element is installed in a region between the optical paths K4A 'far from the light-receiving element so as not to receive the light emitted from A and A', the light emitted from B is not automatically received. Configuration.

[0853] As described above, the infrared light receiving element 8 is installed in a region between the optical path K4A farther from the refraction lens 3 than FA and the light path K4A 'farther from the refraction lens 3 than FA'. By doing so, it is possible to obtain an optical sensor that receives only light rays emitted from a region near the optical axis that is desired to be received.

Although the first to thirty-second embodiments have been described using infrared light as an example, the same configuration can be used to realize both a small light receiving area and a large light receiving amount for visible light, ultraviolet light, and the like. it can.

[0855]

As described above, according to the first infrared sensor of the present invention, at least the light condensing element for condensing the infrared light radiated from the object to be measured, and the light condensing by the light condensing element. An infrared light receiving element for receiving the infrared light, and a housing for holding the light collecting element and the infrared light receiving element, wherein the infrared light receiving element is set apart from a focal position of the light collecting element. With this, the light receiving area is limited. Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. Also, the light receiving element is
By installing the light collecting element away from the focal position of the light collecting element, light incident on the light collecting element from an unnecessary area can be advanced to a position other than the light receiving element, and the light receiving area can be limited.

[0856] In the above infrared sensor, the infrared light receiving element is located on the same side as the point located on the boundary with respect to the optical axis from the point located on the boundary of the light receiving region on the surface of the object to be measured. A point farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element through the edge of the light-collecting element and located at the boundary by the light-collecting element Is located in a region closer to the light-collecting element than the image point of. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

[0857] In the infrared sensor described above, the infrared light receiving element passes through the edge of the light-collecting element on the same side as the point located at the boundary with respect to the optical axis from the point located at the boundary. The triangle formed by the intersection of the optical axis and the optical path reaching the image point of the point located at the boundary by the light-collecting element and the two image points of the point located at the boundary by the light-collecting element Installed in With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0858] In the infrared sensor, the infrared light receiving element is located in a region farther from the light condensing element than an image point of the light condensing element at a point located on a boundary of the light receiving area on the object surface. I do. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

[0859] In the infrared sensor, the infrared light receiving element may be moved from a point located at the boundary through an edge of the light collecting element opposite to a point located at the boundary with the optical axis interposed therebetween. It is installed in a region sandwiched between two optical paths reaching an image point of a point located at the boundary by the light-collecting element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

According to the second infrared sensor of the present invention, at least a light condensing element for condensing infrared light radiated from an object to be measured and an infrared light condensed by the light condensing element are received. An infrared light receiving element, a housing for holding the light collecting element and the infrared light receiving element, and a fixing portion for fixing a direction to an object to be measured; The light receiving area is limited by installing the device away from the position. Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. Further, by installing the light receiving element away from the focal position of the light collecting element, light incident on the light collecting element from an unnecessary area can be advanced to a position other than the light receiving element,
The light receiving area can be limited.

[0861] In the infrared sensor, the infrared light receiving element may be arranged so that the front light-collecting element is located on the same side as the point located on the boundary with respect to the optical axis from the point located on the boundary of the light receiving area on the surface of the object to be measured. It is farther from the light-collecting element than the intersection of the optical path and the optical axis that passes through the edge of the element and reaches the image point of the point located at the boundary by the light-collecting element and is located at the boundary by the light-collecting element. It is installed in a region closer to the light-collecting element than a point image point. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

[0861] In the infrared sensor, the infrared light receiving element is moved from a point located at the boundary to an edge of the light-collecting element on the same side of the optical axis as a point located at the boundary. Within the triangle formed by the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element, and two image points of the point located at the boundary by the light-collecting element Install. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0863] In the infrared sensor, the infrared light receiving element is located in a region farther from the light condensing element than an image point of the light condensing element at a point located on the boundary of the light receiving area on the object surface. Set up to do. Infrared rays from unnecessary areas can be focused on points other than the light receiving element, and the light receiving area can be limited.

[0864] In the infrared sensor, the infrared light-receiving element is moved from the point located at the boundary through the edge of the light-collecting element on the opposite side of the point located at the boundary across the optical axis. It is installed in a region sandwiched between two optical paths reaching an image point of a point located at the boundary by the light-collecting element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0865] In the infrared sensor, the infrared light receiving element is connected to the inner wall of the fixed portion on the same side as the optical axis from the edge of the light collecting element with respect to the optical axis. From the point where the straight line intersects the surface of the tip of the fixed part,
The point passing through the edge of the light-collecting element and intersecting with the surface of the tip of the fixed portion is farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point by the light-collecting element, and It is installed in a region closer to the light-collecting element than an image point of the light-collecting element at a point intersecting with the surface of the front end of the fixed portion. Since a region other than the fixed portion can be used as a light receiving region, a highly accurate infrared sensor which is not affected by a temperature change of the fixed portion can be realized.
Further, since the light receiving amount can be maximized in the light receiving area under the condition that the light from the fixed portion is not received, the S / N is improved and the detection accuracy can be improved.

[0866] In the infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the light collecting element with respect to the optical axis from the edge of the light collecting element. An optical path that passes through the edge of the light-collecting element from a point where the straight line intersects the front end surface of the fixed portion to reach two image points of the light converging element at a point where the straight line intersects the front end surface of the fixed portion; Are located inside a triangle formed by a point intersecting with the optical axis and two image points of the condensing element at a point intersecting with the surface of the fixed portion tip. Infrared rays from the fixed part can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

[0867] In the infrared sensor, the infrared light receiving element may be arranged such that a focal length f of the light collecting element, a radius rs of the infrared light receiving element, and an optical axis from an edge of the light collecting element. The distance rα between the optical axis and a point where a straight line drawn so as to contact the inner wall of the fixed part on the same side as the edge of the light-collecting element, and the light from the edge of the light-collecting element A distance Lα between a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element with respect to an axis and a surface of the tip of the fixed part intersects the light-collecting element; Using the radius r3 of the light collecting element,

[0868]

[Equation 89]

[0869] The light-emitting device is set farther from the light-collecting element by the distance L3 given by

[0870] This realizes a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion.

[0871] In the infrared sensor, the infrared light receiving element is so arranged as to be in contact with the inner wall of the fixed portion on the same side as the edge of the light collecting element with respect to the optical axis from the edge of the light collecting element. The point where the straight line intersects the surface of the tip of the fixed portion is located farther from the light-collecting element than the image point of the light-collecting element. Since a region other than the fixed portion can be used as a light receiving region, a highly accurate infrared sensor which is not affected by a temperature change of the fixed portion can be realized. Further, since the light receiving amount can be maximized in the light receiving area under the condition that the light from the fixed portion is not received, the S / N is improved and the detection accuracy can be improved. Further, in the infrared sensor, the infrared light receiving element may be located on two sides intersecting the front end surface of the fixed portion and opposite points intersecting the front end surface of the fixed portion across the optical axis. It is installed in a region sandwiched between two optical paths that reach an image point by the light-collecting element at two points passing through the edge of the light-collecting element and intersecting the surface of the tip of the fixed part. Infrared rays from the fixed part can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

[0832] In the infrared sensor, the infrared light receiving element may be arranged such that a focal length f of the light collecting element, a radius rs of the infrared light receiving element, and an optical axis from an edge of the light collecting element. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element, and from the edge of the light-collecting element A distance Lα between a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element with respect to the optical axis intersects the surface of the tip of the fixed part and the light-collecting element; Using the radius r3 of the light collecting element,

[0873]

[Equation 90]

[0874] The light source is set farther from the light condensing element than the focal point of the light condensing element by L3 represented by the following formula. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

According to the third infrared sensor of the present invention, at least a light-collecting element that collects infrared light radiated from an object to be measured, and receives the infrared light collected by the light-collecting element. An infrared light receiving element, a housing for holding the light collecting element and the infrared light receiving element, a fixing portion for fixing a direction to an object to be measured, and a lens aperture stop for limiting an effective area of the light collecting element The light receiving area is limited by installing the infrared light receiving element away from the focal point of the light collecting element. Since the infrared light emitted from the object to be measured can be efficiently collected by the light receiving element, the amount of received light can be increased. Further, by installing the light receiving element away from the focal position of the light collecting element, light incident on the light collecting element from an unnecessary area can be advanced to a position other than the light receiving element,
The light receiving area can be limited.

[0887] In the infrared sensor, the infrared light receiving element is so arranged as to contact the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. An optical path from a point where the straight line intersects the surface of the front end of the fixed portion, passes through the edge of the lens aperture stop, and reaches an image point of the light condensing element at a point where the straight line intersects the surface of the front end of the fixed portion. It is located in a region that is farther from the light-collecting element than the intersection of the light-collecting element and that is closer to the light-collecting element than the image point of the light-collecting element at a point that intersects the front end surface of the fixed part. Light incident on the light-collecting element from an unnecessary area can be advanced to a position other than the light-receiving element, and the light-receiving area can be limited.

[0877] In the infrared sensor, the infrared light receiving element may be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. From the point where the drawn straight line intersects the front end surface of the fixed portion, passes through the edge of the lens aperture stop, and reaches the image point of the light condensing element at the cross point with the front end surface of the fixed portion. It is installed inside a triangle formed by the intersection of the optical path and the optical axis and the two image points of the light condensing element at the point of intersection with the front end surface of the fixed part. An optical path and an optical axis that pass through the edge of the lens aperture stop on the same side as the tip of the fixed portion with respect to the optical axis from the tip of the fixed portion and reach the image point at the tip of the fixed portion by the light-collecting element; The light receiving element at a position far from the optical axis even if the light receiving element is located farther from the light condensing element than the intersection with the light condensing element and closer to the light condensing element than the image point of the tip of the fixed part by the light condensing element If it is installed, it will receive infrared rays from the fixed part. This infrared ray can be prevented from being received.

[0878] In the infrared sensor, the infrared light receiving element may be arranged such that the focal length f of the light condensing element, the radius rs of the infrared light receiving element, and the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the lens aperture stop, and the light from the edge of the lens aperture stop A distance Lα between a point where a straight line drawn so as to be in contact with an inner wall of the fixed portion on the same side as an edge of the lens aperture stop with respect to an axis and a surface of a front end of the fixed portion and the lens aperture stop; Using the distance L2 between the lens aperture stop and the condenser element and the aperture radius r2 of the lens aperture stop,

[0877]

[Equation 91]

[0880] The lens is located farther from the light-collecting element than the focal point of the light-collecting element by L3 represented by the following formula, and is located on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part intersects the surface of the tip of the fixed part, the distance rB between a point other than the tip of the fixed part and the optical axis, the light condensing The relationship of rB ≧ rαf (f + L3)> L3 · L2 to the focal length f of the element, the distance L2 between the condenser element and the lens aperture stop, and the distance L3 between the focal point of the condenser element and the infrared receiving element. Holds. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

[0881] In the infrared sensor, the infrared light receiving element is connected to the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. It is installed in a region farther from the light-collecting element than an image point of the light-collecting element at a point where a straight line intersects the surface of the front end of the fixed part. Light incident on the light-collecting element from an unnecessary area can be advanced to a position other than the light-receiving element, and the light-receiving area can be limited.

[0882] In the infrared sensor, the infrared light receiving element may be arranged so that the infrared light receiving element is opposite to a point crossing the front end surface of the fixed portion across the optical axis from two points crossing the front end surface of the fixed portion. It is installed in a region sandwiched between two optical paths that reach an image point by two light condensing elements passing through the edge of the lens aperture stop on the side and intersecting the front end surface of the fixed portion.

[0883] Infrared rays from the fixed portion can be focused on points other than the light receiving element, and the light receiving area can be limited to the vicinity of the optical axis.

[0884] In the infrared sensor, the infrared light receiving element may be arranged such that the focal length f of the light condensing element, the radius rs of the infrared light receiving element, and the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the lens aperture stop, and the distance from the edge of the lens aperture stop A distance Lα between a point where a straight line drawn so as to be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis intersects the surface of the fixed portion tip and the lens aperture stop; Using the distance L2 between the lens aperture stop and the condenser element and the aperture radius r2 of the lens aperture stop,

[0885]

(Equation 92)

[0886] The lens is located farther from the light-collecting element than the focal point of the light-collecting element by L3 represented by the following formula, and is located on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part intersects the surface of the tip of the fixed part, the distance rB between a point other than the tip of the fixed part and the optical axis, the light condensing The relationship of rB ≧ rαf (f + L3)> L3 · L2 to the focal length f of the element, the distance L2 between the condenser element and the lens aperture stop, and the distance L3 between the focal point of the condenser element and the infrared receiving element. Holds. Accordingly, a highly stable infrared sensor that limits the light receiving area near the optical axis and does not receive infrared light from the fixed portion can be realized.

[0887] According to the first optical sensor of the present invention,
At least, a light-collecting element that collects light rays emitted or reflected from the device under test, a light-receiving element that receives light rays collected by the light-collecting element, and a housing that holds the light-collecting element and the light-receiving element A light receiving area is limited by installing the light receiving element away from a focal position of the light collecting element. Since the light emitted from the object can be efficiently collected by the light receiving element, the amount of received light can be increased. Further, by installing the light receiving element away from the focal position of the light collecting element, light incident on the light collecting element from an unnecessary area can be advanced to a position other than the light receiving element,
The light receiving area can be limited. For example, when measuring the luminous intensity distribution of a luminous object, the spatial resolution can be increased by narrowing the light receiving area, and the measuring accuracy can be increased by increasing the amount of received light.

[0888] In the above-mentioned optical sensor, the light receiving element may be an edge of the front light-collecting element on the same side as a point located on the boundary with respect to the optical axis from a point located on the boundary of the light receiving area on the surface of the object to be measured. An image of a point farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element and passing through the light-collecting element. It is installed in a region closer to the light collecting element than a point. Light rays from unnecessary regions can be focused on points other than the light receiving element, and the light receiving region can be limited.

[0889] In the above optical sensor, the light-receiving element is moved from the point located at the boundary to the light-collecting element through the edge of the light-collecting element on the same side as the point located at the boundary with respect to the optical axis. It is installed in a triangle formed by an intersection of an optical path reaching an image point of a point located at the boundary by an optical element and an optical axis, and two image points of a point located at the boundary by the light-collecting element. . With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0890] In the above optical sensor, the light receiving element is provided in a region farther from the light converging element than an image point of the light converging element at a point located on the boundary of the light receiving area on the surface of the measured object. Light rays from unnecessary regions can be focused on points other than the light receiving element, and the light receiving region can be limited.

[0891] In the above-mentioned optical sensor, the light-receiving element passes through the edge of the light-collecting element opposite to the point located on the boundary with respect to the optical axis from the point located on the boundary. It is installed in an area between two optical paths reaching an image point of a point located at the boundary by the element. With this configuration, the light receiving area can be limited to the vicinity of the optical axis.

[0891] The first, second, and third infrared sensors and optical sensors can be easily formed by using a refractive lens, a transmission type diffraction lens, a light collection mirror, or a reflection type diffraction lens as a light collecting element. realizable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram and an optical path diagram of an infrared sensor according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram and an optical path diagram of an infrared sensor according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram and an optical path diagram of an infrared sensor according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram and an optical path diagram of an infrared sensor according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram and an optical path diagram of an infrared sensor according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram and an optical path diagram of an infrared sensor according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram and an optical path diagram of an infrared sensor according to a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram and an optical path diagram of an infrared sensor according to a seventh embodiment of the present invention.

FIG. 9 is a configuration diagram and an optical path diagram of an infrared sensor according to an eighth embodiment of the present invention.

FIG. 10 is a configuration diagram and an optical path diagram of an infrared sensor according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram and an optical path diagram of an infrared sensor according to an eighth embodiment of the present invention.

FIG. 12 is a configuration diagram and an optical path diagram of an infrared sensor according to a ninth embodiment of the present invention.

FIG. 13 is a configuration diagram and an optical path diagram of an infrared sensor according to a tenth embodiment of the present invention.

FIG. 14 is a configuration diagram and an optical path diagram of an infrared sensor according to an eleventh embodiment of the present invention.

FIG. 15 is a configuration diagram and an optical path diagram of an infrared sensor according to a twelfth embodiment of the present invention.

FIG. 16 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirteenth embodiment of the present invention.

FIG. 17 is a configuration diagram and an optical path diagram of an infrared sensor according to a fourteenth embodiment of the present invention.

FIG. 18 is a configuration diagram and an optical path diagram of an infrared sensor according to a fifteenth embodiment of the present invention.

FIG. 19 is a configuration diagram and an optical path diagram of an infrared sensor according to a fifteenth embodiment of the present invention.

FIG. 20 is a configuration diagram and an optical path diagram of an infrared sensor according to a sixteenth embodiment of the present invention.

FIG. 21 is a configuration diagram and an optical path diagram of an infrared sensor according to a sixteenth embodiment of the present invention.

FIG. 22 is a configuration diagram and an optical path diagram of an infrared sensor according to a sixteenth embodiment of the present invention.

FIG. 23 is a configuration diagram and an optical path diagram of an infrared sensor according to a seventeenth embodiment of the present invention.

FIG. 24 is a configuration diagram and an optical path diagram of an infrared sensor according to an eighteenth embodiment of the present invention.

FIG. 25 is a configuration diagram and an optical path diagram of an infrared sensor according to a nineteenth embodiment of the present invention.

FIG. 26 is a configuration diagram and an optical path diagram of an infrared sensor according to a twentieth embodiment of the present invention.

FIG. 27 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-first embodiment of the present invention.

FIG. 28 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-second embodiment of the present invention.

FIG. 29 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-third embodiment of the present invention.

FIG. 30 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-third embodiment of the present invention.

FIG. 31 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-fourth embodiment of the present invention.

FIG. 32 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-fourth embodiment of the present invention.

FIG. 33 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-fourth embodiment of the present invention.

FIG. 34 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-fifth embodiment of the present invention.

FIG. 35 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-sixth embodiment of the present invention.

FIG. 36 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-seventh embodiment of the present invention.

FIG. 37 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-eighth embodiment of the present invention.

FIG. 38 is a configuration diagram and an optical path diagram of an infrared sensor according to a twenty-ninth embodiment of the present invention.

FIG. 39 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirtieth embodiment of the present invention.

FIG. 40 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirty-first embodiment of the present invention.

FIG. 41 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirty-first embodiment of the present invention.

FIG. 42 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirty-second embodiment of the present invention.

FIG. 43 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirty-second embodiment of the present invention.

FIG. 44 is a configuration diagram and an optical path diagram of an infrared sensor according to a thirty-second embodiment of the present invention.

FIG. 45 is a schematic view of an infrared detecting thermometer in the first conventional example.

FIG. 46 is a schematic diagram of an infrared detecting thermometer according to a second conventional example.

FIG. 47 is a configuration diagram and an optical path diagram of an optical sensor according to a thirty-third embodiment of the present invention.

FIG. 48 is a configuration diagram and an optical path diagram of an optical sensor according to a thirty-fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed part 2 Lens aperture stop 3 Refractive lens 4 Infrared light receiving element 5 Transmission type diffractive lens 6 Condensing mirror 7 Reflective type diffractive lens 8 Light receiving element 9 Housing A Point of fixed part tip A 'Point of fixed part tip F Lens Focus of A Image point of A by FA lens Image point of A 'by FA' lens

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuyuki Kanazawa 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Kazunari Nishi, 1006 Kadoma, Kazuma, Osaka Prefecture, Matsushita Electric Industrial

Claims (32)

[Claims] At least a light-collecting element for collecting infrared light radiated from an object to be measured, an infrared light-receiving element for receiving infrared light collected by the light-collecting element, the light-collecting element and the red light An infrared sensor, comprising: a housing that holds an external light receiving element; and wherein the infrared light receiving element is located away from a focal position of the light collecting element to limit a light receiving area. 2. The method according to claim 1, wherein the infrared light receiving element is located on the same side of the optical axis as a point on the same side as a point located on the boundary between an area on the surface of the object to be received and an area on which light reception is not desired. It is farther from the light-collecting element than the intersection of the optical path and the optical axis that reaches the image point of the point located at the boundary by the light-collecting element through the edge of the light-collecting element, and is located at the boundary by the light-collecting element. The infrared sensor according to claim 1, wherein the infrared sensor is provided in a region closer to the light-collecting element than an image point of the target point. 3. The infrared light receiving element passes through the edge of the light-collecting element on the same side as the point located on the boundary with respect to the optical axis from the point located on the boundary, and The intersection of the optical path and the optical axis reaching the image point of the point located at the boundary,
The infrared sensor according to claim 2, wherein the infrared sensor is provided within a triangle formed in a meridional plane of the light-collecting element and formed by two image points of a point located at the boundary by the light-collecting element. 4. The method according to claim 1, wherein the infrared light receiving element is located in a region farther from the light collecting element than an image point by the light collecting element at a point located on a boundary between a region on the object to be measured and a region not to receive light. The infrared sensor according to claim 1, wherein the infrared sensor is installed. 5. The infrared light receiving element passes through an edge of the light-collecting element on a side opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary. The infrared sensor according to claim 4, wherein the infrared sensor is provided in a region between two optical paths in a meridional plane of the light-collecting element that reaches an image point at a point located at a boundary. 6. A light-collecting element for collecting at least infrared light radiated from an object to be measured, an infrared light-receiving element for receiving infrared light collected by the light-collecting element, the light-collecting element and the red light. A housing for holding the external light receiving element, and a cylindrical fixing portion having a hole through which light from the object to be measured to the light-collecting element passes for fixing the direction to the object to be measured, and An infrared sensor, wherein a light receiving area is limited by installing an external light receiving element away from a focal position of the light collecting element. 7. The infrared light receiving element is disposed on the same side as a point on the same side as a point located on the boundary with respect to an optical axis from a point located on a boundary between a region on the object to be received and a region on which light reception is not desired. It is farther from the light-collecting element than the intersection of the optical path and the optical axis that reaches the image point of the point located at the boundary by the light-collecting element through the edge of the light-collecting element, and is located at the boundary by the light-collecting element. The infrared sensor according to claim 6, wherein the infrared sensor is provided in a region closer to the light-collecting element than an image point of the point to be measured. 8. The infrared light receiving element passes the edge of the light-collecting element on the same side as the point located on the boundary with respect to the optical axis from the point located on the boundary, and The intersection of the optical path and the optical axis reaching the image point of the point located at the boundary,
The infrared sensor according to claim 7, wherein the infrared sensor is provided in a triangle formed in a meridional plane of the light-collecting element and formed by two image points of a point located at the boundary by the light-collecting element. 9. The method according to claim 1, wherein the infrared light receiving element is located in a region farther from the light collecting element than an image point by the light collecting element at a point located on a boundary between a region on the object to be received and a region not to receive light. The infrared sensor according to claim 6, wherein the infrared sensor is installed. 10. The infrared light receiving element passes through an edge of the light-collecting element opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary, and The infrared sensor according to claim 9, wherein the infrared sensor is provided in a region between two optical paths in a meridional plane of the light condensing element that reaches an image point at a point located at a boundary. 11. A straight line drawn from the edge of the light-collecting element so as to contact the inner wall of the fixed part on the same side as the edge of the light-collecting element from the edge of the light-collecting element. From the intersection of the optical axis and the optical path reaching the image point of the light-collecting element at the point crossing the edge of the light-collecting element from the point intersecting with the surface of the light-collecting element. 7. The light-emitting device according to claim 6, wherein the light-receiving element is disposed in a region far from the light-collecting element and closer to the light-collecting element than an image point formed by the light-collecting element at a point crossing the front end surface of the fixed portion. Infrared sensor. 12. A straight line drawn from the edge of the light-collecting element so as to contact the inner wall of the fixed part on the same side as the edge of the light-collecting element from the edge of the light-collecting element. The point at which the light passes through the edge of the light-collecting element from the point intersecting with the surface of the light-collecting element and intersects with the surface of the front end of the fixed portion is determined by the light-collecting element.
A meridional plane of the light-collecting element formed by a point at which an optical path reaching two image points intersects the optical axis and two image points by the light-collecting element at a point intersecting with the surface of the fixed end. The infrared sensor according to claim 11, wherein the infrared sensor is installed inside a triangle. 13. An infrared light receiving element, comprising: a focal length f of the light collecting element, a radius rs of the infrared light receiving element, and an edge of the light collecting element with respect to an optical axis from an edge of the light collecting element. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the fixed part, and the distance rα from the edge of the light-collecting element to the optical axis. The distance L between the point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the optical element intersects the surface of the tip of the fixed part and the light-collecting element
Using α and the radius r3 of the light-collecting element, 13. The infrared sensor according to claim 12, wherein the light sensor is disposed farther from the light-collecting element than the focal point of the light-collecting element by L3 given by: 14. A straight line drawn from the edge of the light-collecting element so that the infrared light-receiving element is in contact with the inner wall of the fixed part on the same side as the edge of the light-collecting element with respect to the optical axis. 7. The infrared sensor according to claim 6, wherein the infrared sensor is provided at a position farther from the light-collecting element than an image point formed by the light-collecting element at a point intersecting with the front end surface of the light-receiving element. 15. The light-collecting device according to claim 1, wherein the infrared light receiving element is arranged such that the light-collecting element is located on the opposite side of each of the points intersecting the front end surface of the fixed portion with respect to the optical axis from two points intersecting the front end surface of the fixed portion. It is installed in a region sandwiched between two optical paths in the meridional plane of the light-collecting element, which reaches an image point by the light-collecting element at two points passing through the edge of the element and intersecting the surface of the tip of the fixed portion. The infrared sensor according to claim 14, wherein: 16. An infrared light receiving element comprising: a focal length f of the light-collecting element; a radius rs of the infrared light-receiving element; and an edge of the light-collecting element with respect to the optical axis from the edge of the light-receiving element. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed portion on the same side as the surface of the tip of the fixed portion, and the distance from the edge of the light-collecting element to the optical axis. Distance L between the point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the light condensing element intersects the surface of the tip of the fixed part and the light condensing element
Using α and the radius r3 of the light-collecting element, 16. The infrared sensor according to claim 15, wherein the light sensor is disposed farther from the light-collecting element than the focal point of the light-collecting element by L3 represented by the following expression. 17. A light-collecting element for collecting at least infrared light radiated from an object to be measured, an infrared light-receiving element for receiving infrared light collected by the light-collecting element, the light-collecting element and the red light. A housing for holding the external light receiving element, a cylindrical fixing portion having a hole through which light from the object to be measured to the light-collecting element passes for fixing the direction of the light-collecting element, An infrared sensor comprising a lens aperture stop for limiting an effective area, wherein the light receiving area is limited by disposing the infrared light receiving element away from a focal point of the light collecting element. 18. A fixed line formed by drawing the infrared light receiving element from the edge of the lens aperture stop so as to be in contact with the inner wall of the fixed portion on the same side as the edge of the lens aperture stop with respect to the optical axis. The intersection of the optical path and the optical axis that passes through the edge of the lens aperture stop from the point that intersects the surface of the front end of the lens and reaches the image point of the condensing element at the point that intersects the surface of the front end of the fixed portion. 18. The light-emitting device according to claim 17, wherein the light-receiving element is located farther from the light-collecting element and is located closer to the light-collecting element than an image point formed by the light-collecting element at a point intersecting with the front end surface of the fixed portion. Infrared sensor. 19. A straight line drawn from the edge of the lens aperture stop so as to contact the inner wall of the fixed portion on the same side as the edge of the lens aperture stop from the edge of the lens aperture stop. The intersection of the optical path and the optical axis that passes through the edge of the lens aperture stop from the point that intersects the surface of the front end of the lens and reaches the image point of the condensing element at the point that intersects the surface of the front end of the fixed portion. And two image points formed by the light-collecting element at a point intersecting with the surface of the front end of the fixed part. The light-receiving element is disposed inside a triangle in the meridional plane of the light-collecting element. Item 18. An infrared sensor according to Item 18. 20. The infrared light receiving element, wherein a focal length f of the light-collecting element, a radius rs of the infrared light receiving element, and an edge of the lens aperture stop with respect to an optical axis from an edge of the lens aperture stop. The distance r between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as intersects the surface of the tip of the fixed part
α and a point where a straight line drawn from the edge of the lens aperture stop to the optical axis on the same side as the edge of the lens aperture stop so as to be in contact with the inner wall of the fixed portion intersects the front end surface of the fixed portion. Using the distance Lα from the lens aperture stop, the distance L2 between the lens aperture stop and the light-collecting element, and the aperture radius r2 of the lens aperture stop, L3, which is located farther from the light-collecting element than the focal point of the light-collecting element, and which is on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall intersects the surface of the tip of the fixed part, the distance rB between the point other than the tip of the fixed part and the optical axis, the focal point of the light-collecting element A distance f, a distance L2 between the condenser element and the lens aperture stop;
A distance L3 between the focal point of the light-collecting element and the infrared light receiving element.
20. The infrared sensor according to claim 19, wherein the following relationship is satisfied: rB≥rαf (f + L3)> L3 · L2. 21. A straight line drawn from the edge of the lens aperture stop so as to contact the inner wall of the fixed portion on the same side as the edge of the lens aperture stop from the edge of the lens aperture stop. The infrared sensor according to claim 17, wherein the infrared sensor is provided in a region farther from the light-collecting element than an image point formed by the light-collecting element at a point intersecting with a front end surface. 22. The lens aperture stop, wherein the infrared light receiving element is located at two points intersecting the front end surface of the fixed portion and the lens aperture stop opposite to a point intersecting the front end surface of the fixed portion across the optical axis. At a point between two optical paths in the meridional plane of the light-collecting element reaching two image points formed by the light-collecting element passing through the edge of the fixed part and intersecting the surface of the tip of the fixed part. The infrared sensor according to claim 21, wherein: 23. The infrared light receiving element, wherein the focal length f of the light-collecting element, the radius rs of the infrared light receiving element, and the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the fixed part crosses the surface of the tip of the fixed part, and the distance from the edge of the lens aperture stop to the optical axis. A distance Lα between a point at which a straight line drawn so as to be in contact with the inner wall of the fixed part on the same side as the edge of the lens aperture stop and a surface of the fixed part tip and the lens aperture stop; Using the distance L2 to the optical element and the aperture radius r2 of the lens aperture stop, L3, which is located farther from the light-collecting element than the focal point of the light-collecting element, and which is on the same side as the edge of the lens aperture stop with respect to the optical axis from the edge of the lens aperture stop. The distance rα between the optical axis and a point where a straight line drawn so as to be in contact with the inner wall intersects the surface of the tip of the fixed part, the distance rB between the point other than the tip of the fixed part and the optical axis, the focal point of the light-collecting element A distance f, a distance L2 between the condenser element and the lens aperture stop;
A distance L3 between the focal point of the light-collecting element and the infrared light receiving element.
23. The infrared sensor according to claim 22, wherein a relationship of rB ≧ rαf (f + L3)> L3 · L2 is satisfied. 24. A light-collecting element for condensing at least light emitted or reflected from an object to be measured, a light-receiving element for receiving light condensed by the light-condensing element, the light-collecting element and the light-receiving element. An optical sensor, comprising: a housing for holding an element; and a light receiving area is limited by installing the light receiving element away from a focal position of the light collecting element. 25. The light-collecting element, wherein the light-receiving element is on the same side as a point located on the boundary with respect to the optical axis from a point located on a boundary between a region on the object to be received and a region on which light reception is not desired. A point farther from the light-collecting element than the intersection of the optical path and the optical axis reaching the image point of the point located at the boundary by the light-collecting element through the edge of the light-collecting element and located at the boundary by the light-collecting element 25. The optical sensor according to claim 24, wherein the optical sensor is provided in a region closer to the light-collecting element than the image point. 26. The light-receiving element is moved from a point located at the boundary to an edge of the light-collecting element on the same side as a point located at the boundary with respect to the optical axis and to the boundary formed by the light-collecting element. A triangle in the meridional plane of the light-collecting element formed by an intersection of an optical path reaching the image point of the located point and the optical axis, and two image points of a point located at the boundary by the light-collecting element. 26. The optical sensor according to claim 25, wherein the optical sensor is installed inside the optical sensor. 27. The light-receiving element is provided in a region farther from the light-collecting element than an image point of the light-collecting element at a point located on a boundary between a region on the object to be received and a region not to receive light. The optical sensor according to claim 24, wherein: 28. The light-receiving element passes through an edge of the light-collecting element opposite to a point located on the boundary with respect to an optical axis from a point located on the boundary, and is connected to the boundary by the light-collecting element. 28. The optical sensor according to claim 27, wherein the optical sensor is provided in a region between two optical paths in a meridional plane of the light condensing element that reaches an image point of a located point. 29. The infrared sensor according to claim 1, wherein the light-collecting element is a refractive lens. 30. An infrared sensor according to claim 1, wherein said light-collecting element is a transmission type diffraction lens. 31. The infrared sensor according to claim 1, wherein the light-collecting element is a light-collecting mirror. 32. The infrared sensor according to claim 1, wherein the light-collecting element is a reflection type diffraction lens.