JP2012098200A - Laser range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact laser range finder capable of preventing mixing of light from a light source in a light receiving optical path, increasing a measuring distance, and achieving high accuracy.SOLUTION: A laser range finder 300 includes, sequentially from the target object side: a visual optical system including an objective lens 30, a partial reflection member 20, a prism member 50, and an eyepiece 80; a first optical path branch surface 21a disposed on the partial reflection member 20 to branch a first measuring optical path from the optical path of the visual optical system; a second optical path branch surface 54a which is one reflection surface in the prism member 50 and branches a second measuring optical path from the optical path of the visual optical system; a light source 10 disposed in one of the first measuring optical path and the second measuring optical path to emit light projected to the target object via the objective lens 30; and a light receiving element 40 disposed in the other of the first measuring optical path and the second measuring optical path to receive reflected light reflected by the target object and converged by the objective lens 30.

Description

  The present invention relates to a laser rangefinder.

  The laser rangefinder has a light-transmitting lens system and a light-receiving lens system, projects light onto the target object via the light-transmitting lens system, and receives the reflected light via the light-receiving lens system. (For example, refer to Patent Document 1).

JP 2002-350543 A

  In order to reduce the size of such a laser distance meter, it is conceivable to configure all of collimation, light transmission and light reception with a single objective lens. However, with such a configuration, the light transmission optical path and the light reception optical path are arranged close to each other, so that a part of the light emitted from the light source is mixed in the light reception optical path inside the laser distance meter. As a result, noise occurs, the S / N ratio decreases, and the distance measurement accuracy decreases.

  The present invention has been made in view of such problems, and prevents light from the light source from being mixed into the light receiving optical path, and can be downsized to increase the measurement distance and increase the measurement accuracy. Is to provide a simple laser rangefinder.

In order to solve the above problems, the laser distance meter according to the present invention is provided in the collimating optical system including the objective lens, the partial reflection member, and the erecting prism in order from the target object side, and the partial reflection member. A first optical path branch surface for branching the first measurement optical path from the optical path of the collimation optical system, and one reflecting surface in the erecting prism, and the second measurement optical path is branched from the optical path of the collimation optical system A second light path branching surface to be disposed; a light source that is disposed on either the first measurement light path or the second measurement light path and that emits light to be projected onto the target object via the objective lens; A light receiving element that is disposed on the other of the measurement optical path and the second measurement optical path and receives the light reflected by the target object and collected by the objective lens, and includes a first optical path branch plane. Existing between the optical path branch plane of the first optical path and the second optical path branch plane When the distance on the optical axis to the next optical surface on each image side is di, the refractive index of the medium on the image side of each optical surface is ni, and the focal length of the objective lens is f, the following equation 0 .05 ≦ (Σdi / ni) /f≦0.5
It satisfies the following conditions.

  In such a laser rangefinder, it is preferable that the first optical path branch surface has a reflection region that transmits visible light and reflects the light, and a transmission region that transmits visible light and the light.

  In such a laser distance meter, the second optical path branching surface preferably reflects visible light and transmits the light.

Further, such a laser distance meter has the following formula 20 ° ≦ θ1 ≦ 40 °, where θ1 is the incident angle of the light with respect to the first optical path branch plane.
It is preferable to satisfy the following conditions.

Further, such a laser distance meter has the following formula 15 ° ≦ θ2 ≦ 40 °, where θ2 is the incident angle of the light with respect to the second optical path branch plane.
It is preferable to satisfy the following conditions.

  In such a laser distance meter, the collimating optical system preferably has an eyepiece for observing an image formed by the objective lens.

  In addition, such a laser distance meter preferably moves at least a part of the objective lens so as to have a component in a direction orthogonal to the optical axis of the collimating optical system.

  Further, such a laser distance meter preferably moves at least a part of the objective lens along the optical axis of the collimating optical system when focusing.

  When the laser distance meter according to the present invention is configured as described above, the light transmitting optical path and the light receiving optical path are arranged at an appropriate distance, so that a part of the light emitted from the light source is inside the laser distance meter. Therefore, it is difficult for noise to be mixed into the light receiving optical path, and it is possible to increase the measurement distance and the measurement accuracy with a small size.

It is explanatory drawing for demonstrating the structure of the light transmission and light reception for distance measurement, Comprising: The case where the light transmission area | region of a partial reflection member is made into a reflection area is shown. It is explanatory drawing for demonstrating the structure of the light transmission and light reception for distance measurement, Comprising: The case where the light transmission area | region of a partial reflection member is made into a transmissive area | region is shown. It is explanatory drawing which shows the structure of a laser rangefinder when a light transmission area | region is made into a reflection area. It is explanatory drawing which shows the structure of a laser rangefinder when a light transmission area | region is made into a transmissive area | region. It is explanatory drawing which shows the structure of the laser rangefinder for anti-vibration and focusing with an objective lens.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, a configuration for performing light transmission and light reception for distance measurement using a single objective lens using the laser distance meter 100 shown in FIG. 1 will be described. The laser distance meter 100 includes a light source 10 that is a semiconductor laser, a partial reflection member 20, an objective lens 30, and a light receiving element 40. The light source 10 is disposed at or near the focal point of a light transmission lens system including the objective lens 30. The partial reflection member 20 has a partial reflection surface 21 that is disposed obliquely with respect to the optical axis, and is disposed between the light source 10 and the objective lens 30. The partial reflection surface 21 is divided into three regions, a substantially rectangular light transmitting region 21a positioned so as to include the optical axis, and two substantially rectangular light receiving regions 21b arranged above and below the light transmitting region 21a. , Is composed of. In the first embodiment, the light transmitting region 21a is configured as a reflective region (R) that reflects light from the light source 10, and the light receiving region 21b transmits reflected light incident from the objective lens 30 side. It is configured as a transmissive region (T). And the light receiving element 40 is arrange | positioned in the position (The focus of the light receiving lens system containing the objective lens 30 or its vicinity) where the light which permeate | transmitted this light reception area | region 21b condenses.

  In the laser rangefinder 100 having such a configuration, a laser beam (hereinafter also referred to as “measurement light”) emitted from the light source 10 in a pulse shape is a light transmission region 21 a formed in a substantially central portion of the partial reflection surface 21. And is incident on the objective lens 30, converted into substantially parallel light by the objective lens 30, and projected onto a target object (not shown). Then, a part of the measurement light reflected and diffused by the target object (hereinafter also referred to as “reflected light”) is incident on the objective lens 30 to be condensed, and a light receiving region formed on the partial reflection surface 21. The light passes through 21 b and is collected on the light receiving element 40. Therefore, by processing the electrical signal output from the light receiving element 40 according to the received reflected light by a distance calculation unit (not shown) and measuring the time from the emission of the measurement light to the reception of the reflected light, this time and The distance from the laser rangefinder 100 to the target object can be calculated using the speed of light. As described above, when the transmission of the measurement light and the reception of the reflected light are configured using the common partial reflection member 20 and the objective lens 30, the laser distance meter 100 can be reduced in size.

  Further, like the laser distance meter 200 shown in FIG. 2, the partial reflection surface 21 formed on the partial reflection member 20 has a light transmission region 21a as a transmission region (T) and two light reception regions 21b as reflection regions (R). ). In this case, the measurement light emitted from the light source 10 passes through the light transmission region 21 a formed at the center of the partial reflection surface 21, enters the objective lens 30, and is converted into substantially parallel light by the objective lens 30. The reflected light that is projected onto a target object (not shown), reflected by the target object, and diffused is partially incident on the objective lens 30 and collected, and reflected by the light receiving region 21b formed on the partial reflection surface 21. And is configured to form an image on the light receiving element 40. Even in such a configuration, the arrangement of the light source 10 (the light emitting unit 10a) and the partial reflection surface 21 (the light transmitting region 21a and the light receiving region 21b) is as described above.

  A laser range finder 300 having the above-described laser range finder 100 as a basic configuration and capable of measuring a target object while collimating through the objective lens 30 will be described with reference to FIG. The laser distance meter 300 includes an objective lens 30, a partial reflection member 20, a prism member 50, a protective filter 60, a liquid crystal display element 70, and an eyepiece 80 in order from the object side. The Further, the condenser lens 11 and the light source 10 are arranged on the first measurement optical path branched by the partial reflection surface 21 of the partial reflection member 20. The light transmission region 21a of the partial reflection surface 21 is configured by a dichroic mirror that reflects laser light (the above-described measurement light and infrared light) and transmits visible light (that is, this partial reflection). The member 20 has a dichroic prism configuration).

  The measurement light emitted from the light source 10 is collected by the condenser lens 11 and enters from the incident surface 20 a of the partial reflection member 20. Then, total reflection is performed twice in the partial reflection member 20 and guided to the light transmission region 21 a of the partial reflection surface 21. The angle of the partial reflection surface 21 with respect to the optical axis and the light source so that the measurement light emitted from the light source 10 and incident on the light transmission region 21a of the partial reflection surface 21 is reflected along the optical axis of the objective lens 30. The position of 10 is adjusted. Then, the measurement light reflected by the light transmission region 21a of the partial reflection surface 21 is converted into substantially parallel light by the objective lens 30 and projected onto the target object.

  In addition, the incident surface 20a of the partial reflection member 20 is configured such that the measurement light from the light source 10 enters the incident surface 20a substantially perpendicularly. Further, the measurement light emitted from the light source 10 and transmitted through the partial reflection surface 21 (measurement light transmitted through the light transmission region 21a or measurement light transmitted through the light reception region 21b) is transmitted so as not to enter the light receiving lens system. An infrared absorption filter 22 that absorbs the measurement light is disposed at a position where the measured light is incident.

  On the other hand, a part of the measurement light projected on the target object is reflected and scattered by the target object, and a part of the measurement light enters the objective lens 30 as described above. Then, the light is condensed by the objective lens 30 and enters the partial reflection member 20, passes through the light receiving region 21 b of the partial reflection surface 21, and enters the prism member 50. The prism member 50 is joined to the first prism 51 and the second prism 52 that constitute an erecting prism that converts an inverted image of a subject (target object) formed by the objective lens 30 into an erect image, and the second prism 52. And a second optical path branching surface that reflects visible light for collimating the target object on the joint surface and transmits measurement light (reflected light) that is laser light to separate the light. And a third prism 53 on which a wavelength separation surface 54a is formed. As described above, the dichroic prism 54 is formed by the second prism 52 and the third prism 53. The background light blocking filter 41 and the light receiving element 40 are disposed on the second measurement optical path branched by the second optical path branch plane (wavelength separation plane 54a).

  The reflected light that has passed through the partial reflection surface 21 (light receiving region 21b) of the partial reflection member 20 and has entered the first prism 51 of the prism member 50 undergoes total reflection three times within the first prism 51, and the second prism. 52 is incident on a wavelength separation surface 54 a formed on the joint surface between the second prism 52 and the third prism 53. As described above, since this wavelength separation surface 54a transmits laser light, the reflected light is transmitted through the wavelength separation surface 54a and emitted from the emission surface 53a of the third prism 53, and is transmitted through the background light blocking filter 41. It is condensed on the light receiving element 40. Note that such reflected light (measurement light reflected by the target object) includes light other than this measurement light, so that when it is received by the light receiving element 40, it becomes noise and lowers the SN ratio. I will let you. For this reason, the background light blocking filter 41 is used to block light other than the measurement light as much as possible to improve the SN ratio. The exit surface 53a of the third prism 53 is configured such that the reflected light is incident (emitted) substantially perpendicularly to the exit surface 53a.

  Further, in the laser range finder 300 having such a configuration, light (visible light) emitted from the subject (target object) is collected by the objective lens 30, passes through the partial reflection member 20, and is transmitted to the first prism 51. , And is totally reflected three times in the first prism 51 to enter the second prism 52, and further enters the wavelength separation surface 54a. Since the wavelength separation surface 54a reflects visible light as described above, the visible light from the target object is reflected by the wavelength separation surface 54a, and further totally reflected once within the second prism 52 and then reflected by the second prism. After exiting from 52 and passing through the protective filter 60, it is formed as a primary image (upright image) of the subject. A liquid crystal display element 70 is disposed at substantially the same position as the primary image, and the measurer superimposes the primary image of the subject and the image displayed on the liquid crystal display element 70 via the eyepiece lens 80. Magnification can be observed. As described above, the collimating optical system including the objective lens 30, the erecting prism (the first and second prisms 51 and 52), the protective filter 60, the liquid crystal display element 70, and the eyepiece lens 80 allows the measurer to set the target object. Can be collimated.

  Here, the reflected light (laser light) can be separated from visible light by passing through the wavelength separation surface 54a as described above, but remains without being separated by this wavelength separation surface 54a (wavelength separation surface). Such laser light is removed by the protective filter 60 so that the laser light (reflected by 54a) does not reach the eye of the person to be measured.

  Now, conditions required for the optical system in order to configure such a laser distance meter 300 will be described. First, the laser distance meter 300 includes a first optical path branch surface (the light transmission region 21a of the partial reflection surface 21), and from the first optical path branch surface to the second optical path branch surface (wavelength separation surface 54a). The distance (on the optical axis) from each surface of the optical surface existing between the surfaces to the next optical surface on the image side is di, the refractive index of the medium on the image side of each surface is ni, and the objective lens 30 It is desirable to satisfy the following formula (1) where f is the focal length. Note that Σ is a function that calculates di / ni on each surface i and calculates the sum of them.

0.05 ≦ (Σdi / ni) /f≦0.5 (1)

  Conditional expression (1) is a portable laser distance meter 300 that is used by hand, and a part of the measurement light emitted from the light source 10 is mixed in the light receiving optical path inside the laser distance meter 300. This is a condition for preventing noise and reducing the S / N ratio of the reflected light detection and reducing the accuracy of distance measurement. If the lower limit value of the conditional expression (1) is not reached, the light transmission optical path and the light reception optical path are too close to each other, and a part of the measurement light emitted from the light source 10 is mixed into the light reception optical path inside the laser distance meter 300. Noise, which may reduce the S / N ratio and reduce the distance measurement accuracy. On the contrary, if the upper limit value of conditional expression (1) is exceeded, the entire laser distance meter 300 becomes too large, and it is difficult to downsize it so that it can be used by hand.

  In addition, the laser distance meter 300 has a measurement light (emitted from the light source 10 and incident on the first optical path branching surface (the light transmission region 21a of the partial reflection surface 21) and reflected by the first optical path branching surface). It is desirable that the following conditional expression (2) is satisfied, where θ1 is an incident angle of a light beam that travels on the optical axis of the objective lens 30 after reflection.

20 ° ≦ θ1 ≦ 40 ° (2)

  Conditional expression (2) is a condition for appropriately configuring the first optical path branch plane. If the lower limit of conditional expression (2) is not reached, the partial reflection member (dichroic prism) 20 becomes too large to ensure the amount of measurement light necessary for distance measurement, and a compact laser rangefinder 300 is provided. Can not do. On the contrary, if the upper limit value of the conditional expression (2) is exceeded, the light transmission region 21a having sufficient characteristics to reflect visible light and transmit laser light (infrared light) with a relatively small number of layers. It becomes difficult to create a partially reflecting member (dichroic prism) 20 in which is formed.

  Further, the laser distance meter 300 travels on the optical axis of the objective lens 30 among the reflected light (light reflected by the target object) incident on the second optical path branch surface (wavelength separation surface 54a), and the second optical path. It is desirable that the following conditional expression (3) is satisfied when the incident angle of the light beam incident on the branch plane is θ2.

15 ° ≦ θ2 ≦ 40 ° (3)

  Conditional expression (3) is a condition for appropriately configuring the second optical path branch plane. If the lower limit value of conditional expression (3) is not reached, an erecting prism (prism member 50) effective for miniaturization of the laser distance meter 300 is created, or visible light is reflected therein, and laser light (infrared) It becomes difficult to select a reflection surface (wavelength separation surface 54a) that constitutes the dichroic prism 54 that transmits light. Conversely, if the upper limit of conditional expression (2) is exceeded, a dichroic prism 54 having sufficient characteristics to reflect visible light and transmit laser light (infrared light) with a relatively small number of layers is created. It becomes difficult to do.

  Further, the laser distance meter 300 shown in FIG. 3 superimposes the measurement light on the optical axis of the objective lens 30 at the first optical path branch surface, and separates the reflected light toward the light receiving element 40 at the second optical path branch surface. As shown in FIG. 4, the laser distance meter 200 shown in FIG. 2 in which the positions of the light source 10 and the light receiving element 40 are reversed may be used as a basic configuration. The configuration of the laser distance meter 400 shown will be described. In addition, about the member same as FIG. 3, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the case of the laser distance meter 400 shown in FIG. 4, the light transmission lens system includes the condenser lens 11, the prism member 50 on which the wavelength separation surface 54 a is formed, and the partial reflection surface 21 in order from the light source 10 side. The partial reflection member 20 and the objective lens 30 are configured. The light receiving lens system includes an objective lens 30 and a partial reflection member 20 in order from the measurement object side. Here, the light receiving region 21b of the partial reflection surface 21 is configured by a dichroic mirror that reflects laser light (the above-described measurement light and infrared light) and transmits visible light. That is, the background light blocking filter 41 and the light receiving element 40 are arranged on the first measurement optical path branched by the light receiving region 21b (first optical path branching surface) constituting the partial reflection surface 21 of the partial reflection member 20, and the prism. The condenser lens 11 and the light source 10 are arranged on the second measurement optical path branched by the wavelength separation surface 54a (second optical path branching surface) of the member 50. Further, in the example shown in FIG. 3, the light (reflected light or visible light) collected by the objective lens 30 and transmitted through the partial reflection member 20 is incident on the first prism 51 and the second prism 52 in this order. In FIG. 4, the incident light enters the second prism 52, and the visible light separated by the wavelength separation surface 54 a enters the first prism 51. It is configured.

  In such a laser distance meter 400, the measurement light emitted from the light source 10 is collected by the condenser lens 11 and enters the third prism 53 from the incident surface 53a, and is a wavelength separation surface which is a second optical path branch surface. Incident on 54a. Since the wavelength separation surface 54 a transmits laser light, the measurement light passes through the wavelength separation surface 54 a and enters the second prism 52, and is emitted from the second prism 52 once with total internal reflection. Then, this measurement light is incident on the partial reflection member 20, and a part of the measurement light is transmitted through the light transmission region 21 a of the partial reflection surface 21 that is the first optical path branching surface and is converted into substantially parallel light by the objective lens 30. And projected onto the measurement object. In addition, since the measurement light reflected by the partial reflection surface 21 enters the infrared absorption filter 22 and is absorbed, the measurement light does not enter the light receiving lens system.

  On the other hand, a part of the measurement light projected on the measurement object is reflected and scattered by the measurement object, and is incident on the objective lens 30 again and collected. The reflected light collected by the objective lens 30 enters the partial reflection member 20 and is reflected by the light receiving region 21b of the partial reflection surface 21, and then totally reflected twice in the partial reflection member 20 to be emitted. The light is emitted from 20 a, passes through the background light blocking filter 41, and forms an image on the light receiving element 40. The light (visible light) emitted from the subject (target object) is collected by the objective lens 30, passes through the partial reflection member 20, enters the second prism 52, and enters the second prism 52. The total reflection is performed once and enters the wavelength separation surface 54a. Since the wavelength separation surface 54a reflects visible light, it is reflected by the wavelength separation surface 54a, enters the first prism 51, is totally reflected three times inside, and exits the first prism 51, and the protective filter 60 is removed. After passing through, it is formed as a primary image (upright image) of the subject. A liquid crystal display element 70 is disposed at substantially the same position as the primary image, and the measurer superimposes the primary image of the subject and the image displayed on the liquid crystal display element 70 via the eyepiece lens 80. Magnification can be observed.

  In the laser distance meter 400, the reflected light transmitted through the partial reflection surface 21 (reflected light transmitted through the light transmitting region 21a or the light receiving region 21b) is incident on the second prism 52, undergoes total reflection once, and has a wavelength. Although the light is transmitted through the separation surface 54a and separated, the reflected light (laser light) reflected without being transmitted through the wavelength separation surface 54a is cut by the protective filter 60 and therefore does not reach the eye of the measurer.

  The conditional expression described using the laser distance meter 300 can also be applied to the laser distance meter 400. In the case of the laser distance meter 400, in the conditional expression (2), the reflected light incident on the first optical path branch surface (the light receiving region 21b of the partial reflection surface 21) and reflected (of the light reflected by the target object, The incident angle of the light beam traveling on the optical axis of the objective lens 30 and reflected by the first optical path branch surface is θ1, and in the conditional expression (3), it is incident on the second optical path branch surface (wavelength separation surface 54a). The incident angle of the measurement light (the light beam emitted from the light source 10 and transmitted through the second optical path branch plane and then traveling on the optical axis of the objective lens 30) becomes θ2.

  Moreover, in the handheld portable laser rangefinders 300 and 400 as described above, there is a problem that it is difficult to determine the measurement position because the image of the target object collimated by camera shake is blurred. Therefore, at least a part of the objective lens constituting the laser rangefinder 300 shown in FIG. 3 is an anti-vibration lens, and this anti-vibration lens is moved so as to have a component in a direction orthogonal to the optical axis, thereby obtaining an image. A description will be given of a laser rangefinder 500 configured to suppress the blurring. In addition, about the member same as the laser distance meter 300, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  A laser distance meter 500 shown in FIG. 5 replaces the objective lens 30 of the laser distance meter 300 shown in FIG. 3 with a lens system (objective lens 530) suitable for performing vibration isolation. In other words, the objective lens 530 includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side. It is configured to perform vibration isolation by moving so as to have a component in a direction orthogonal to. Since the first lens group G1 disposed on the object side has a positive refractive power, the first lens group G1 can focus the light beam, and the diameter of the second lens group G2 can be reduced. Therefore, it becomes easy to move the second lens group G2 for image stabilization. In this case, a gyro sensor (such as an angular velocity sensor) for detecting camera shake is provided, and the image stabilizing lens is moved in a direction to cancel the detected camera shake.

  In the laser rangefinder 500 having such a configuration, when measuring a distance to a short-distance object, at least a part of the objective lens 530 is a focusing lens, and the focusing lens is moved along the optical axis. Thus, it is possible to configure so that an object at a short distance can be focused and its image can be observed clearly. In the laser distance meter 500 having the configuration shown in FIG. 5, the second lens group G2 is a focusing lens.

  The entire objective lens 530 can be used as an anti-vibration lens or a focusing lens, or the objective lens 530 is composed of three or more lens groups, and a part of the objective lens 530 is an anti-vibration lens or a focusing lens. Can do. At this time, each of image stabilization and focusing may be performed by different lens groups.

  Then, the Example based on the structure of the laser distance meters 300 and 400 mentioned above is described.

[First embodiment]
FIG. 3 shows the configuration of the optical system of the laser rangefinder 300 according to the first embodiment. In the laser distance meter 300 shown in FIG. 3, on the optical path from the measurement object to the light receiving element 40, an objective lens 30 including a cemented lens in which a biconvex lens and a biconcave lens are joined in order from the measurement object side, and a flat plate shape. A wavelength separation surface on a joint surface obtained by joining a partial reflection member 20 having a partial reflection surface 21 formed on the optical member, a first prism 51 having a flat entrance surface and an exit surface, and a second prism 52 and a third prism 53. A dichroic prism 54 having a flat entrance surface and an exit surface, and a flat-shaped background light blocking filter 41 are disposed.

  Table 1 below shows specification values and condition corresponding values of optical members on the optical path from the measurement object of the laser rangefinder 300 according to the first example to the light receiving element 40. In Table 1, f represents the focal length. In the specification table, the first column m is the number of the lens surface from the measurement object side along the direction of travel of the light beam, the second column r is the curvature radius of each lens surface, and the third column d is each The distance from the optical surface to the next optical surface on the optical axis, the fourth column nd and the fifth column νd indicate the refractive index and Abbe number for the d-line, respectively. Note that the radius of curvature of 0.000 indicates a plane, and the refractive index of air of 1.0000 is omitted. Further, the optical surfaces corresponding to the surface numbers in Table 1 are indicated by “m” in FIG. Here, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other length units listed in all the following specification values, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. The description of these codes and the description of the specification table are the same in the following embodiments.

(Table 1)
f = 112.0

m r d nd νd
1 73.370 5.0 1.51680 64.1
2 -43.200 2.0 1.62004 36.3
3 -142.755 61.3
4 0.000 2.0 1.51680 64.1
5 0.000 2.0 1.51680 64.1
6 0.000 2.0
7 0.000 33.9 1.51680 64.1
8 0.000 0.4
9 0.000 5.4 1.51680 64.1
10 0.000 3.1 1.51680 64.1
11 0.000 7.6
12 0.000 3.0 1.51680 64.1
13 0.000 5.3
14 0.000

(1) (Σdi / ni) /f=0.265
(2) θ1 = 30 °
(3) θ2 = 24 °

  Thus, it can be seen that the laser rangefinder 300 according to the first example satisfies all the conditional expressions (1) to (3). The first optical path branch surface 21a corresponds to the fifth surface, the second optical path branch surface 54a corresponds to the tenth surface, and the light receiving element 40 corresponds to the fourteenth surface.

[Second Embodiment]
FIG. 4 shows the configuration of the optical system of the laser rangefinder 400 according to the second embodiment. In the laser distance meter 400 shown in FIG. 4, on the optical path from the measurement object to the light source 10, an objective lens 30 composed of a cemented lens in which a biconvex lens and a biconcave lens are cemented in order from the measurement object side, and a flat plate-shaped object A wavelength separation surface 54a is formed on the joint surface where the partial reflection member 20 in which the partial reflection surface 21 (light receiving region 21b) is formed on the optical member and the second prism 52 and the third prism 53 are joined, and the entrance surface and the exit surface. A flat dichroic prism 54 and a condenser lens 11 made of a positive meniscus lens having a convex surface facing the measurement object are disposed. Table 2 below shows the specifications of the optical members on the optical path from the measurement object to the light source 10 of the laser rangefinder 400 according to the second embodiment and the condition corresponding values.

(Table 2)
f = 112.0

r d nd νd
1 73.370 5.0 1.51680 64.1
2 -43.200 2.0 1.62004 36.3
3 -142.755 57.4
4 0.000 4.0 1.51680 64.1
5 0.000 6.0 1.51680 64.1
6 0.000 2.0
7 0.000 6.5 1.51680 64.1
8 0.000 8.1 1.51680 64.1
9 0.000 5.4 1.51680 64.1
10 0.000 3.0
11 8.000 2.0 1.75520 27.6
12 15.800 9.6
13 0.000

(1) (Σdi / ni) /f=0.139
(2) θ1 = 30 °
(3) θ2 = 24 °

  Thus, it can be seen that the laser rangefinder 400 according to the second embodiment satisfies all the conditional expressions (1) to (3). The first optical path branch surface 21b corresponds to the fifth surface, the second optical path branch surface 54a corresponds to the ninth surface, and the light source 10 corresponds to the thirteenth surface.

20 Partial reflection member 21 Partial reflection surface 21a Light transmission region (first optical path branch surface)
30 Objective Lens 40 Light Receiving Element 50 Prism Member (Erecting Prism) 54a Wavelength Separation Surface (Second Optical Path Branching Surface)
80 Eyepiece 300,400 Laser distance meter

Claims (8)

A collimating optical system consisting of an objective lens, a partially reflecting member, and an erecting prism in order from the target object side,
A first optical path branching surface provided on the partial reflection member and branching the first measurement optical path from the optical path of the collimating optical system;
A second reflecting surface in the erecting prism, which branches a second measuring light path from the light path of the collimating optical system;
A light source that is disposed in one of the first measurement optical path and the second measurement optical path and that emits light to be projected onto the target object via the objective lens;
A light receiving element that is disposed on the other of the first measurement optical path or the second measurement optical path and receives the light reflected by the target object and condensed by the objective lens,
A distance on the optical axis from the first optical path branch plane to the second optical path on the image side for each optical plane that includes the first optical path branch plane and is between the first optical path branch plane and the second optical path branch plane. When di is assumed, the refractive index of the medium on the image side of each optical surface is ni, and the focal length of the objective lens is f, the following expression 0.05 ≦ (Σdi / ni) /f≦0.5
A laser rangefinder that satisfies the following conditions.   2. The laser distance according to claim 1, wherein the first optical path branching surface includes a reflection region that transmits visible light and reflects the light, and a transmission region that transmits visible light and the light. Total.   The laser rangefinder according to claim 1 or 2, wherein the second optical path branching surface reflects visible light and transmits the light. When the incident angle of the light with respect to the first optical path branching surface is θ1, the following equation 20 ° ≦ θ1 ≦ 40 °
The laser rangefinder according to any one of claims 1 to 3, wherein the following condition is satisfied. When the incident angle of the light with respect to the second optical path branching surface is θ2, the following formula 15 ° ≦ θ2 ≦ 40 °
The laser rangefinder according to any one of claims 1 to 4, wherein the following condition is satisfied.   The laser collimator according to any one of claims 1 to 5, wherein the collimating optical system includes an eyepiece that observes an image formed by the objective lens.   The laser rangefinder according to claim 1, wherein at least a part of the objective lens is moved so as to have a component in a direction orthogonal to the optical axis of the collimating optical system.   The laser rangefinder according to any one of claims 1 to 7, wherein at the time of focusing, at least a part of the objective lens is moved along the optical axis of the collimating optical system.

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