JPH0943496A - Back focus adjustment device of camera loaded on flying body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time required for adjusting a back focus by providing the plural pin holes of a correction optical system on a surface inclined from a vertical surface to an optical axis. SOLUTION: A reticle 3 is installed to be fixed on the optical axis connecting a light source 2 and a collimator 4 by setting the pin hole side thereof on the light source side. The reticle 3 is provided with a light transmission part at the center thereof and at the point-symmetric position with respect to the center and formed as the inclined surface with respect to a light receiving surface. Then, the plural pin holes are formed along the inclined surface. Therefore, a distance between the light source 2 and the respective pin holes becomes different according to what position on the inclined surface of the light transmission part the pin hole exists. Then, light transmitted through the pin holes formed at the different positions is inputted to the detector 7 of a camera loaded on a flying body 5 by a different focus. The positions of the respective pin holes of the reticle 3 are given from the reference pin hole as displacement quantity and required shin thickness is calculated and obtained based on the focal length of the collimator 11 and the focal length of the camera 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back focus of a vehicle-mounted camera that is mounted on a flying object such as an aircraft, an artificial satellite, or a space transportation vehicle and acquires an image using a two-dimensional solid-state image sensor. Regarding the adjusting device.

[0002]

2. Description of the Related Art A camera mounted on a flying object such as an aircraft, an artificial satellite, or a space transportation machine (hereinafter, a camera for mounting a flying object) focuses on infinity and shoots the earth from outer space. Therefore, in order to obtain a back focus characteristic that is focused at infinity, focus adjustment by a back focus adjustment device is required before mounting on a flying object.

The back focus is adjusted to change the thickness of the shim installed in the camera for mounting the flying object so as to focus at infinity, and the back focus adjusting device determines the thickness of the shim. A test for designing and a test for actually installing the designed shim on a vehicle-mounted camera to confirm its performance are performed.

A conventional back focus adjusting device and an adjusting procedure by the adjusting device will be described with reference to FIGS. 1 and 4. In FIG. 1, a back focus adjustment device 1 includes a light source 2 and a collimator 4 that converts light from the light source 2 into parallel light and projects the light onto a lens 6 of a camera 5 for mounting an air vehicle.
And a reticle 3 provided on the optical axis connecting the light source 2 and the collimator 4. The reticle 3 is the light source 2
Pinhole that allows the light from the side to pass to the collimator 4 side,
A large number of them are scattered on the light receiving surface and are configured to be movable along the optical axis. The light from the light source 2 passes through the pinhole of the reticle 3 and reaches the collimator 4, where it is collimated and given to the lens 6 of the flying vehicle mounting camera 5. The light entering the lens 6 is detected by the detector 7 which is a two-dimensional solid-state imager, and its image data is obtained.

The procedure for adjusting the back focus of the flying object mounting camera 5 using the back focus adjusting device 1 is as follows (see FIG. 4). That is, the flying object mounting camera 5 is assembled with the shim 6 removed, and installed at a predetermined adjustment position (step 1). The reticle 3 is fixed to the initial setting location of the back focus adjustment device 1 (step 2). When the light source 2 is turned on, the light passes through the pinhole of the reticle 3, is collimated by the collimator 4, and is emitted to the flying vehicle mounting camera 5. The radiated light is condensed by the lens 6 of the camera 5 for mounting a flying object and is focused on the light receiving surface of the detector 7 to obtain image data (step 3).

Next, the reticle 3 is slid in the optical axis direction by a certain distance (step 4). Similar to the above procedure, light is emitted from the light source 2 and the image data is acquired by the flying object mounting camera 5 (step 5). While sliding the reticle 3, the operation of acquiring image data with the flying object mounting camera 5 is repeated until the reticle 3 slides to the designated position (step 6). The shim necessary for the camera 5 is designed (step 7).

Next, the designed shim 8 is inserted between the lens 6 and the detector 7 to assemble the flying object mounting camera 5 (step 8). To confirm the performance,
The back focus adjustment device 1 acquires back focus data (step 9). The adjustment procedure is repeated until the result satisfies the back focus characteristic (step 10).

[0008]

As described above, in the conventional back focus adjustment of the vehicle-mounted camera, it is necessary to slide the reticle by the designated distance and acquire the data at each position. There is a problem that it takes a lot of time.

Further, Japanese Patent Application Laid-Open No. 1-223413 describes a technique for correcting image blur by moving two wedge-shaped optical elements along a boundary surface so that the optical systems have different thicknesses. However, even if this technique is applied to the above-mentioned back focus adjustment, the fact that the relative position of the wedge is different and the data must be measured at each stage is no different from the above-mentioned conventional technique, and the focus is still maintained. The problem that adjustment takes time is not solved.

The present invention has been made in view of the above-mentioned conventional problems, and a flying vehicle camera capable of shortening the adjustment time by performing the data acquisition once during the back focus adjustment. The present invention aims to provide a back focus adjustment device for the.

[0011]

In order to achieve the above object, the invention according to claim 1 is mounted on a flying object, and a back focus adjusting device for a flying object mounting camera for acquiring image data by a two-dimensional solid-state image pickup device. A correction optical having a light source, a collimator for converting the light from the light source into parallel light, and a pinhole provided on the optical axis connecting the light source and the collimator and passing the light from the light source to the collimator side. System and the pinhole of the above correction optical system,
A plurality of them are provided on a surface inclined from the surface perpendicular to the optical axis.

With this structure, the light from the light source is
It passes through different pinholes on the inclined surface of the correction optical system to reach the collimator, becomes parallel light, enters the lens of the camera for mounting the flying object, is condensed, and forms an image on its detector. Since each pinhole on the correction optical system is formed at a different position on the inclined surface, the distance from the light source to each pinhole is different, which causes each pinhole to move in the optical axis direction of the camera image plane. The position is different. That is, the target pinhole from the position of the reference pinhole.
The displacement of (i) in the optical axis direction is ai, and the amount of movement of the camera image plane due to the light passing through the target pinhole (i) from the camera image plane of the light passing through the reference pinhole. The following relation holds when is bi.

Bi = ai (fs / fc) ² (1) where ai: pinhole displacement amount, bi: camera image plane movement amount fs: camera focal length, fc: collimator focal length.

Therefore, the light passing through the different pinholes of the correction optical system can obtain different positions of the camera image plane, and from the data, it becomes possible to design the shim to be used in the vehicle-mounted camera.

According to a second aspect of the present invention, in the back focus adjusting device for a flying object mounting camera according to the first aspect, the correction optical system forms a plurality of inclined surfaces on a light receiving surface perpendicular to the optical axis. A plurality of pinholes are formed along each of the inclined surfaces.

With this configuration, the same position of the camera image plane is obtained from the corresponding pinholes on the different inclined surfaces, and the adjustment accuracy thereof is guaranteed.

According to a third aspect of the present invention, in the back focus adjusting device for a flying object mounting camera according to the second aspect, the plurality of inclined surfaces are arranged at positions symmetrical with respect to the center of the light receiving surface. There is.

With such a configuration, the deviation of the camera image plane is obtained from the corresponding pinholes on the different inclined surfaces, and the tilt of the detector is adjusted so as to eliminate the deviation, whereby the detector for the camera lens is detected. The inclination of is corrected.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings. The basic configuration of the back focus adjusting device according to the present invention is similar to that of the prior art described above, the light source 2 and the light from the light source 2 are converted into parallel light to the lens 6 of the flying vehicle mounting camera 5. It comprises a collimator 4 for projecting light and a reticle 3 provided on the optical axis connecting the light source 2 and the collimator 4 (see FIG. 1).

2A and 2B are views showing an embodiment of the reticle according to the present invention. FIG. 2A is a front view seen from the collimator side, and FIG. 2B is an enlarged side sectional view of the light transmitting portion. . As shown in these figures, the reticle 3 comprises a thin plate made of a translucent member such as glass and a non-transmissive material in which a large number of pinholes 10 are provided in close contact with the thin plate. It is fixedly installed on the optical axis connecting 4 with the pinhole 10 side (light receiving surface side) as the light source 2 side.

The reticle 3 is, as shown in FIG.
Nine light-transmitting parts 11 are provided in total at the center and at positions symmetrical with respect to the center. Each translucent part 11 is shown in FIG.
As shown in FIG. 3, the pinhole 10 is formed as a surface inclined with respect to the light receiving surface of the reticle 3, and a plurality of pinholes 10 are formed along the inclined surface of each inclined light transmitting portion 11. Therefore, the distance from the light source 2 to each pinhole 10 is
The light passing through the pinholes 10 at different positions is input to the detector 7 of the flying object mounting camera 5 at different focal points, depending on which position on the inclined surface of the light transmitting unit 11 is. In addition, each pinhole 10 formed in the transparent portion 11
Has a diameter of about 10 to 20 μm, and the distance between the pinholes 10 in the optical axis direction is about 50 μm.

Next, the adjustment procedure by the back focus adjusting device using the reticle 3 will be described with reference to the flowchart of FIG. First of all,
Assemble with the shim 6 removed, and install at a predetermined adjustment position (step 1). When the light source 2 is turned on, the light passes through the pinhole of the reticle 3, is collimated by the collimator 4, and is emitted to the flying object mounting camera 5. The irradiated light is condensed by the lens 6 of the camera 5 for mounting the flying object and is focused on the light receiving surface of the detector 7 to obtain image data (step 2).

In this case, each pinhole 1 of the reticle 3
The position of 0 is given as a displacement amount ai from the reference pinhole 10a, and from the focal length fc of the collimator and the focal length fs of the camera, from the formula (1), the movement amount bi of the image plane of the camera, that is, the required amount Shim thickness is obtained. Further, the back focus at several places on the screen can be obtained at the same time by the light that has passed through the pinhole 10 of each light transmitting portion 11, and the mounting inclination of the detector 7 can also be obtained at the same time.

The shim 8 required for the flying object mounting camera 5 is designed from the image data obtained by the above procedure (step 3). The manufactured shim 8 is inserted between the lens 6 and the detector 7, and the flying object mounting camera 5 is assembled (step 4). For confirmation, the back focus adjustment device 1 acquires back focus data again with the shim 8 attached (step 5). The result is
The adjustment procedure is repeated until the back focus characteristic is satisfied (step 6).

[0025]

As described above, according to the present invention, a plurality of pinholes for the correction optical system of the back focus adjusting device are provided on the surface inclined from the surface perpendicular to the optical axis.
Data acquisition at the time of back focus adjustment can be completed once, and the back focus adjustment time can be shortened.

Further, by forming a plurality of inclined surfaces on the light receiving surface perpendicular to the optical axis and forming a plurality of pinholes along the respective inclined surfaces, the above correction optical system is constructed, which is different. A corresponding pinhole on the tilted surface provides a similar camera image plane position, ensuring its adjustment accuracy.

Furthermore, by arranging the plurality of inclined surfaces at positions symmetrical with respect to the center of the light receiving surface, the shift of the camera image forming surface can be obtained from the corresponding pinholes on the different inclined surfaces. By tilting the detector so as to eliminate the deviation, the inclination of the detector with respect to the camera lens can be corrected.

[Brief description of drawings]

FIG. 1 is a schematic side view of a back focus adjusting device and a flying object mounting camera for explaining a configuration for adjusting a back focus.

FIG. 2 is a diagram showing an embodiment of a reticle according to the present invention, in which (a) is a front view seen from the collimator side;
(B) is an enlarged side sectional view of the translucent part.

FIG. 3 is a flowchart showing a back focus adjustment procedure of the present invention.

FIG. 4 is a flowchart showing a conventional back focus adjustment procedure.

[Explanation of symbols]

 1 Back focus adjustment device 2 Light source 3 Reticle 4 Collimator 5 Flying object camera 6 Lens 7 Detector 8 Shim 10 Pinhole 10a Reference pinhole 11 Translucent part

Claims (3)

[Claims] 1. A back focus adjusting device for a flying object mounting camera, which is mounted on a flying object and acquires image data by a two-dimensional solid-state imager, comprising: a light source; and a collimator for converting light from the light source into parallel light. It comprises a correction optical system provided on the optical axis connecting the light source and the collimator and having a pinhole for passing the light from the light source to the collimator side, and the pinhole of the correction optical system is arranged on the optical axis. A back focus adjustment device for a vehicle-mounted camera, characterized in that a plurality of them are provided on a surface inclined from a vertical surface. 2. The correction optical system is characterized in that a plurality of inclined surfaces are formed on a light receiving surface perpendicular to the optical axis, and a plurality of pinholes are formed along the respective inclined surfaces. The back focus adjusting device for a camera for mounting a flying object according to claim 1. 3. The back focus adjusting device for a vehicle mounted camera according to claim 2, wherein the plurality of inclined surfaces are arranged at positions symmetrical with respect to the center of the light receiving surface.