JPH06160696A - Image detecting optical device - Google Patents

Abstract

PURPOSE:To provide an image detecting optical device capable of giving the degree of freedom to the position of the exit pupil of an objective optical system and reducing load in the case of optical design. CONSTITUTION:The image detecting optical device detecting the image of an object by using a detector 12 with light from the object condensed through the objective optical systems 11a and 11b is provided with aperture-stop means 13 and 14 provided so as to mode in the optical axis direction of the optical systems 11a and 1b between the optical systems 11a and 11b and the detector 12, driving means 15 and 16 moving the means 13 and 14, and a control means 17 detecting information concerning the exit pupil of the optical systems 11a and 11b and controlling the driving means based on detected information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device having an interchangeable optical system.

[0002]

2. Description of the Related Art A conventional image detecting optical device is shown in FIG.
As shown in (a), a lens 101a as an objective optical system that forms an image of an object (not shown), and a detection element that detects the image.
A cold shield 103a, which is a cooled metal diaphragm, is disposed between the detection element 102 and 102, and heat radiation from structures other than the object such as the inner wall of the lens barrel is not incident on the detection element 102. And the cold shield 103a is the lens
Since it is the aperture stop of 101a, the position of the exit pupil of the lens 101a is the position of the cold shield 103a. This cold shield 103a is the detection element 102 or this detection element.
Since it is fixed to the cooler that cools the 102, the lens 10
The position and size of the exit pupil of 1a were constant.

[0003]

In the conventional image detecting optical device as described above, referring to FIG. 5B, consider a case where the objective optical system is replaced with the lens 101a from the lens 101b. In FIG. 5 (b), since the cold shield 103a that serves as the aperture stop of the image detection optical device is fixed, the lens
The exit pupil of 101b is uniquely determined.

However, the specifications of the objective optical system (focal length,
Depending on the angle of view, the F-number, etc., it may be difficult to perform an optical design with good imaging performance at the exit pupil position determined by the cold shield (aperture stop). For example, as shown in FIG. 5 (b), the lens 101b as the objective optical system has a longer focal length than the lens 101a, and therefore, when the exit pupil is at the position of the cold shield 103a, a good image is formed. It becomes difficult to design the optical system to obtain the performance. Then, for example, in the lens 101b, if the optical design is carried out so that the light ray B shown by the broken line in the figure passes through the lens 101b, the optical design of the lens 101b can be improved.

Therefore, it is an object of the present invention to provide an image detecting optical device which can give a degree of freedom to the position of the exit pupil of an objective optical system to reduce the load in optical design.

[0006]

In order to achieve the above-mentioned object, the image detecting optical device according to the present invention has the following constitution. For example, as shown in FIG. 1, the objective optical system (1
The image detection optical device that detects the image of the object by the detector (12) by the light from the object condensed via (1a, 11b) is an objective optical system between the objective optical system and the detector. Aperture stop means (13, 14) movably provided in the optical axis direction, drive means (15, 16) for moving the aperture stop means, and information about the exit pupil of the objective optical system are detected and detected. And a control means (17) for controlling the driving means based on the information.

The aperture stop means is composed of a plurality of aperture stops (13, 14) having different aperture diameters, and the driving means (15, 16) is at least one of the plurality of aperture stops.
It may be configured to move one. Further, for example, as shown in FIG. 4, the aperture stop means (33) is constructed so that the aperture diameter is variable, and the drive means (38, 39) move the aperture stop means and change the aperture diameter. It may be configured as follows.

[0008]

With the above construction, in the present invention, the position of the aperture stop means can be matched according to the position of the exit pupil of the objective optical system. Therefore, the restriction on the exit pupil position in the optical design of the objective optical system can be eliminated. Furthermore, even if an optical system having a different exit pupil position is exchanged, the aperture stop means can be arranged at the exit pupil position, so that the aperture stop means can effectively block stray light and heat radiation from other than the object. You can

Further, when the objective optical system is a zoom lens, even if the exit pupil position changes during zooming, the aperture stop means can be arranged so as to match the exit pupil position. It becomes possible to detect the image under good image forming performance by blocking the heat radiation of. In the image detection optical system according to the present invention, the changed exit pupil position and the position of the aperture stop means can be matched even when the exit pupil position changes when the distance to the object changes.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are schematic views showing a first embodiment in which an image detecting optical device according to the present invention is applied to an infrared optical device. In FIGS. 1 (a) and 1 (b), infrared light from an object (not shown) is detected by a charge-coupled two-dimensional image sensor (CCD) via an interchangeable lens 11a as an objective optical system. It is incident on the element 12. In order to cool the detection element 12, a Dewar bottle 18 is provided around the detection element 12. This Dewar bottle 18 has a Dewar window 19 for transmitting infrared light, and the inside thereof is kept in a substantially vacuum state.
Then, a Joule-Thomson cooler (not shown) is arranged on the rear side of the detecting element 12 to keep the inside of the detecting element 12 and the Dewar bottle 18 at a temperature of about 77K. Inside the Dewar bottle 18, there are provided cold shields 13 and 14 which can move along the optical axis Ax1 direction of the interchangeable lens 11a. It is configured to be smaller than the opening diameter of the shield 14. Since the cold shields 13 and 14 are cooled, infrared light (heat radiation) does not enter the detection element 12 except from the openings of the cold shields 13 and 14. That is, the cold shields 13 and 14 are interchangeable lenses 11.
It becomes the aperture stop of a.

In this case, the aperture stop (cold shield 13, 14) is located on the image side (detection element 12 side) of the interchangeable lens 11a. Then, by arranging the cold shield 14 having the same aperture diameter as the exit pupil of the interchangeable lens 11a at the designed exit pupil position of the interchangeable lens 11a, unnecessary infrared radiation can be blocked. it can. That is, for the interchangeable lens 11a, aperture matching (exit pupil of the optical system,
A state in which the aperture and the aperture of the aperture stop match in size and position) is established.

Next, aperture matching between the design of the exit pupil of the interchangeable lens and the cold shield will be described. Figure 1
In the image detection optical device shown in (a) and (b), the drive unit 15 for moving the cold shield 13 along the direction of the optical axis Ax1 and the cold shield 14 as the drive means are the same as those of the optical axis Ax1. A drive unit 16 for moving along the direction is provided, and a control unit 17 for controlling the positions of the cold shields 13 and 14 is provided. This controller 17
Drives the drive unit 15 and the drive unit 16 based on the exit pupil information (detection information) regarding the exit pupil position and the exit pupil diameter of the interchangeable lens stored in the memory unit 10a provided in the interchangeable lens 11a.

Hereinafter, referring to FIGS. 1 (a), 1 (b) and FIG.
The control of the positions of the cold shields 13 and 14 by the control unit 17 will be described in detail. [Step 101] First, the control unit 17 controls the interchangeable lens 11a.
The exit pupil information relating to the exit pupil position and the exit pupil diameter of the interchangeable lens 11a is read out from the memory section 10a in the inside, and step 1
Move to 02.

[Step 102] In Step 102,
The control unit 17 determines whether the exit pupil diameter of the interchangeable lens 11a is larger than the aperture diameter of the cold shield 13. If the exit pupil diameter is larger than the aperture diameter of the cold shield 13, the process proceeds to step 103. If the exit pupil diameter is smaller than the aperture diameter of the cold shield 13, the process proceeds to step 105. . Since the exit pupil diameter of the interchangeable lens 11a is now larger than the aperture diameter of the cold shield 13, the process proceeds to step 103.

[Step 103] In step 103,
The control unit 17 selects to move the cold shield 14 and proceeds to step 104. [Step 104] In step 104, the control unit 17
Information on the exit pupil position of the interchangeable lens 11a is transmitted to the drive unit 16, and the cold shield 14 is moved to this exit pupil position.

The cold shield 13 may be arranged at any position as long as it does not block the infrared light flux passing through the cold shield 14. Next, FIG.
As shown in (b), interchangeable lens 11a to interchangeable lens 11b
Consider the case of exchanging with. The exit pupil diameter of this interchangeable lens 11b is smaller than the exit pupil diameter of the interchangeable lens 11a, and its exit pupil position is closer to the detection element 12 side than the exit pupil position of the interchangeable lens 11a. The exit pupil information regarding the pupil diameter is stored in the memory unit 10b.

When the interchangeable lens 11b is mounted on the main body of the image detecting optical device, the control section 17 executes the above step 101 to exchange the exit pupil position and the exit pupil diameter of the interchangeable lens 11b. The data is read from the memory section 10b in the lens 11b, and the process proceeds to step 102. In step 102, the control unit 17 determines whether the read exit pupil diameter is larger than the aperture diameter of the cold shield 13. At this time, the exit pupil diameter of the interchangeable lens 11b is set to the cold shield 13
Since it is smaller than the opening diameter of, the process proceeds to step 105.

[Step 105] In Step 105,
The control unit 17 selects to move the cold shield 13 and proceeds to step 106. [Step 106] In Step 106, the control unit 17
Information on the exit pupil position of the interchangeable lens 11b is transmitted to the drive unit 15, and the cold shield 13 is moved to this exit pupil position.

The cold shield 14 may be arranged anywhere as long as it does not block the infrared light flux passing through the cold shield 13. in this way,
In the first embodiment of the present invention, even if the exit pupil position and the exit pupil diameter of the interchangeable lens are different for each interchangeable lens, the cold shield of the image detecting optical device can be positioned according to the exit pupil. The image detection can be performed with good imaging performance without being affected by infrared light emitted from other than the object. Further, since there are no restrictions on the exit pupil position and the exit pupil diameter of the interchangeable lens, the load on the optical design of this interchangeable lens can be reduced.

Next, a second embodiment according to the present invention will be described with reference to FIGS. 3 (a) and 3 (b). FIGS. 3 (a) and 3 (b) are diagrams schematically showing a second embodiment according to the present invention, and FIGS.
The members having the same function as are given the same reference numerals. Here, in order to simplify the description, only the differences from FIGS. 1A and 1B will be described. In the second embodiment, mirror apertures 23 and 24 are provided instead of the cold shields 13 and 14 in the first embodiment. These mirror apertures 23 and 24 are provided with mirror surfaces 23M and 24M that are mirror-finished inside, and infrared light from an object (not shown) passes through the openings of the mirror apertures 23 and 24. Then, it reaches the detection element 12 in the Dewar bottle 18. Further, when the mirror surfaces 23M and 24M are seen from the detection element 12, only the cooled parts can be seen, so that infrared light emitted from other than the object does not enter the detection element 12.

Also in the second embodiment shown in FIGS. 3 (a) and 3 (b), the control unit 17 includes a memory unit 20a provided in the interchangeable lens 21a and a memory unit 20b provided in the interchangeable lens 21b. The mirror apertures 23 and 24 are moved along the optical axis Ax2 direction on the basis of the exit pupil information relating to the exit pupil position and the exit pupil diameter of each interchangeable lens stored in FIG.
As a result, it is possible to detect an image with a good imaging performance without being affected by infrared light due to radiation from other than the object.

As described above, also in the image detecting optical device using the mirror aperture instead of the cold shield,
The restrictions on the exit pupil position and the exit pupil diameter of the interchangeable lens are eliminated, and the load on the optical design of this interchangeable lens can be reduced.
Further, since it is not necessary to cool the mirror aperture, the internal structure of the Dewar bottle 18 can be simplified. In each of the above-described embodiments, the cold shield or the mirror aperture as the aperture stop has an aperture diameter that matches the exit pupil diameter of each interchangeable lens, but an aperture stop having an aperture diameter smaller than this aperture diameter is used. If provided, the amount of radiation incident on the detection element can be limited. This allows
For example, because the radiation amount is very large, it is possible to detect a hot object where the image signal is saturated.

Next, a third embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). FIGS. 4 (a) and 4 (b) are diagrams schematically showing a third embodiment of the present invention, and in order to simplify the explanation, the same functions as those in FIGS. 1 (a) and 1 (b) are shown. The same reference numerals are given to the members indicating. In FIGS. 4 (a) and 4 (b), the variable diaphragm 33 movable in the optical axis Ax3 direction of the interchangeable lens 31a.
Is provided in the Dewar bottle 18, and this variable diaphragm 33
The diameter of the opening (opening diameter) is variable. A drive unit 38 that drives the variable diaphragm 33 to move in the optical axis Ax3 direction and a drive unit 39 that drives the variable diaphragm 33 to change the aperture diameter are provided. Are controlled by the control unit 37.

The control of the aperture diameter of the variable diaphragm 33 and the control of the position of the variable diaphragm 33 in the optical axis direction by the control unit 37 will be described below. First, the control unit 37 reads out the exit pupil information regarding the exit pupil position and the exit pupil diameter of the interchangeable lens 31a from the memory unit 30a in the interchangeable lens 31a. Then, based on this exit pupil information, the drive unit 38 is controlled to control the variable diaphragm 33.
Is arranged at the exit pupil position of the interchangeable lens 31a, and the drive unit 39 is controlled to change the aperture diameter of the variable diaphragm 33 to the exit pupil diameter of the interchangeable lens 31a.

Next, the interchangeable lens 31a to the interchangeable lens 31b
Consider the case of exchanging with. At this time, the control unit 37 reads out the exit pupil information regarding the exit pupil position and the exit pupil diameter of the interchangeable lens 31b stored in the memory unit 30b in the interchangeable lens 31b. After that, the control unit 37 controls the drive unit 38 and the drive unit 39 based on this exit pupil information to arrange the variable diaphragm 33 at the exit pupil position of the interchangeable lens 31b and exchange the aperture diameter of the variable diaphragm 33. The exit pupil diameter of the lens 31b is changed. As a result, image detection can be performed with good imaging performance without being affected by infrared light from other than the object.

When the numerical aperture (F number) of the interchangeable lens 31a or 31b is reduced, the drive unit 38 may be driven so that the aperture diameter of the variable diaphragm 33 is reduced.
As a result, even a high-temperature object whose image signal is saturated in the detection element can be detected. As described above, in the image detecting optical device according to the third example, there are no restrictions on the exit pupil position and the exit pupil diameter of the interchangeable lens, so that the load on the optical design of the interchangeable lens can be reduced.

In the third embodiment, the above-mentioned second
Similar to the embodiment, the image side of the variable diaphragm 33 (the side of the detecting element 12) may be mirror-finished to downsize the image detecting optical device itself. Further, in each of the embodiments of the present invention, when a zoom lens is applied as an interchangeable lens, if the exit pupil position according to zooming and the exit pupil information regarding the exit pupil system are stored in the memory unit, the exit pupil is zoomed. Even with a zoom lens whose position fluctuates, image detection can always be performed with good imaging performance. Further, the optical design of the zoom lens can be performed without the constraint that the exit pupil position is constant.

In each of the above-described embodiments, the detection information regarding the exit pupil of the objective optical system is electrically transmitted. However, a notch or the like is provided on the objective optical system side so that the image detecting optical device main body side is provided. It may be detected mechanically. Further, in this embodiment, the image detecting optical device is an infrared optical device for detecting infrared light, but it goes without saying that the image detecting optical device according to the present invention is not limited to the infrared optical device.

[0029]

As described above, in the image detecting optical device according to the present invention, since the aperture stop is arranged in accordance with the exit pupil of the objective optical system, it is possible to perform detection under good image forming performance. Becomes Furthermore, since there is no restriction on the exit pupil position of the objective optical system, the optical design according to the specifications of this objective optical system can be easily performed.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a first embodiment according to the present invention.

FIG. 2 is a flowchart showing the operation of the first embodiment according to the present invention.

FIG. 3 is a diagram schematically showing the configuration of a second embodiment according to the present invention.

FIG. 4 is a diagram schematically showing a configuration of a third embodiment according to the present invention.

FIG. 5 is a diagram showing a configuration of a conventional image detection optical device.

[Explanation of symbols]

 10a, 10b ··· Memory unit, 11a, 11b ··· Interchangeable lens (objective optical system), 12 ··· Detection element, 13, 14 ··· Cold shield, 15, 16 ··· Drive unit, 17 ··· Control unit, 18 Dewar bottle, 19 Dewar window,

Claims (3)

[Claims] 1. An image detection optical device in which an image of an object is detected by a detector by light from the object condensed through the objective optical system, wherein the image is detected between the objective optical system and the detector. An aperture stop means movably provided in the optical axis direction of the objective optical system, a drive means for moving the aperture stop means, and information regarding an exit pupil of the objective optical system is detected, and based on the detection information. And a control unit that controls the driving unit. 2. The aperture stop means has a plurality of aperture stops having different aperture diameters, and the drive means moves at least one of the plurality of aperture stops. 1. The image detection optical device described in 1. 3. The aperture stop means is configured so that the aperture diameter is variable, and the drive means moves the aperture stop means and changes the aperture diameter. The image detection optical device described.