Space camera point source transmittance test device and method based on reverse light path principle

Abstract

The device and method for testing the point source transmittance of a space camera based on the principle of reverse light path belongs to the field of stray light testing technology, and specifically relates to the stray light test of a space camera; it solves the problem that the test device is expensive and the test accuracy and test threshold are affected by stray light in the existing stray light test of large-aperture space cameras; the device includes: a light energy detector, a flat surface light source, a lens fixture to be tested, a darkroom, and a test tank; the light energy detector is used to parse the complete PST curve in the direction of the light path from the flat surface light source to a given optical entrance and then to infinity. The device and method for testing the point source transmittance of a space camera based on the principle of reverse light path are suitable for testing the point source transmittance of a space camera.

Description

Technical Field

[0001] The present invention relates to the technical field of stray light testing, and in particular to stray light testing of a space camera. Background Art

[0002] When the space camera is in orbit, it will be interfered by stray light from direct sunlight or diffuse reflection from the earth. In order to ensure that the stray light elimination measures taken by the space camera in orbit can effectively eliminate the stray light interference, it is necessary to conduct a complete stray light test on the space camera on the ground.

[0003] Traditional stray light testing is mainly point source transmittance testing, where point source transmittance is an effective parameter for evaluating stray light levels.

[0004] In the traditional point source transmittance test system, because it is necessary to simulate infinite imaging, the test system contains a collimator; at the same time, since most space cameras are large-aperture cameras, and most transmission-type collimators are small-aperture, a reflective collimator is required for aperture matching; the reflective collimator is expensive, which can reach several million yuan, greatly increasing the cost of the test system or device; at the same time, the primary and secondary mirrors and other mirrors of the collimator will produce scattering, thereby affecting the accuracy and test threshold of the test system or device, which to a certain extent limits the application of the traditional point source transmittance test system. Summary of the invention

[0005] The present invention proposes a space camera point source transmittance test device and method based on the reverse light path principle, which solves the problems of expensive test device cost and test accuracy and test threshold being affected by stray light in existing large-aperture space camera stray light test.

[0006] The technical solution of the space camera point source transmittance test device based on the reverse light path principle of the present invention is as follows:

[0007] The device comprises: a light energy detector, a flat surface light source, a lens fixing member to be tested, a darkroom and a test tank;

[0008] The light energy detector and the test tank are arranged inside the darkroom;

[0009] The flat surface light source and the lens fixing member to be tested are arranged in the test tank; the lens fixing member to be tested is used to fix the lens to be tested;

[0010] A flat surface light source is arranged at a given distance on one side of the lens fixing member to be tested;

[0011] On the other side of the lens fixing member to be tested, the test tank is provided with a light-transmitting opening of a given angle, and the light-emitting area of ​​the flat surface light source faces the light-transmitting opening;

[0012] The light energy detector is arranged outside the test tank; the light energy detector is used to receive the light emitted from the given optical entrance by moving a number of angles with the given optical entrance in the test tank as the center and a given distance as the radius, and is also used to analyze the complete PST curve in the direction of the light path from the flat surface light source to the given optical entrance and then to infinity according to the preset relationship and the received light.

[0013] Further, a preferred embodiment is provided, wherein the device further comprises: a guide rail;

[0014] The guide rail is an arc-shaped guide rail, which is arranged in a dark room, and the light energy detector is slidably connected to the guide rail via a slider.

[0015] Furthermore, a preferred embodiment is provided, wherein the light energy detector is a detection camera or a light meter.

[0016] Furthermore, a preferred embodiment is provided, in which the shape and size of the light emitting area of ​​the flat surface light source are consistent with the shape and size of the actual focal plane of the lens to be tested.

[0017] Furthermore, a preferred embodiment is provided, wherein the flat surface light source is a uniform radiator.

[0018] Furthermore, a preferred embodiment is provided, wherein the darkroom has a visible infrared absorption rate of greater than 0.95.

[0019] Further, a preferred embodiment is provided, the material of the darkroom is matte paint or optical ultra-black coating material

[0020] Further, a preferred embodiment is provided, wherein the preset relationship is:

[0021]

[0022] Among them, according to the reversible principle of optical path, E1 is the illumination of the central field of view reaching the light energy detector, and E2 is the illumination of the non-central field of view reaching the light energy detector.

[0023] The present invention also proposes a method for testing the point source transmittance of a space camera based on the reverse light path principle, and its technical solution is as follows:

[0024] The method is implemented based on the above-mentioned device, and the method comprises the following steps:

[0025] S1. Place the light energy detector at the corresponding field of view position of the object side;

[0026] S2, fixing the lens to be tested on the lens fixing member to be tested, and setting the flat surface light source at the focal plane position of the lens to be tested; taking the optical entrance of the lens to be tested as the given optical entrance;

[0027] S3, light up the flat surface light source;

[0028] S4, moving the light energy detector to several angles with the optical entrance of the lens to be tested as the center and a given distance as the radius to receive the light emitted from the light-transmitting opening, and obtaining illumination data at different angles;

[0029] S5. According to the illumination data at different angles and the preset relationship, the point source transmittance of the lens to be tested in the direction of the optical path from the focal plane position to the optical entrance and then to infinity is obtained.

[0030] Further, a preferred embodiment is provided, in the step S4, the light emitted from the light-transmitting opening is received by moving at several angles, and the angle step length of each movement is as follows:

[0031] If the light energy detector is within the avoidance angle range, the step length of the angle of each movement of the light energy detector is x, x∈[0.01°, 1°];

[0032] If the light energy detector is outside the avoidance angle range, the step length of the angle of each movement of the light energy detector is y, y∈[0.5°, 3°], and y>x.

[0033] The present invention has the following beneficial effects:

[0034] 1. The space camera point source transmittance test device based on the reverse light path principle described in the present invention utilizes the reversible principle of the light path so that the test device no longer needs to simulate infinite imaging, that is, no large-aperture reflective collimator is required, which not only greatly reduces the cost of the test device, but also eliminates the interference of stray light caused by mirror scattering of the collimator, greatly improving the test accuracy and test threshold of the PST test device.

[0035] 2. The space camera point source transmittance test device based on the reverse light path principle described in the present invention can effectively eliminate the light pollution caused by the flat surface light source 4 and the lens to be tested by using a test tank.

[0036] 3. The space camera point source transmittance testing device based on the reverse light path principle described in the present invention blocks external interference light through a dark room.

[0037] The device and method for testing the point source transmittance of a space camera based on the reverse light path principle of the present invention are suitable for testing the point source transmittance of a space camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 This is a structural diagram of a space camera point source transmittance testing device based on the reverse light path principle in one embodiment of the present invention;

[0040] Reference numerals: 1. guide rail; 2. light energy detector; 3. lens fixing member to be tested; 4. flat surface light source; 5. darkroom; 6. test tank. DETAILED DESCRIPTION

[0041] In order to make the technical solutions and advantages of the present invention more clearly described, the specific implementation methods of the present invention will be further described in detail and completely in conjunction with the accompanying drawings. The various implementation methods described below are only part of the preferred solutions of the present invention, rather than all implementation methods; the various implementation methods described below are intended to explain the present invention and cannot be understood as limitations on the present invention; the reasonable combination of technical features defined in the various implementation methods of the present invention, and all other implementation methods obtained by ordinary technicians in the field without creative work based on the implementation methods of the present invention, are within the scope of protection of the present invention.

[0042] Implementation Method 1: Combination Figure 1 This embodiment describes a point source transmittance test device for a space camera based on the reverse light path principle. The specific implementation contents are as follows:

[0043] A space camera point source transmittance test device based on the reverse light path principle, the device comprising: a light energy detector 2, a flat surface light source 4, a lens fixture to be tested 3, a darkroom 5 and a test tank 6;

[0044] The light energy detector 2 and the test tank 6 are arranged inside the darkroom 5;

[0045] The flat surface light source 4 and the lens fixing member 3 to be tested are arranged in the test tank 6; the lens fixing member 3 to be tested is used to fix the lens to be tested;

[0046] On one side of the lens fixing member 3 to be tested, a flat surface light source 4 is arranged at a given distance;

[0047] On the other side of the lens fixing member 3 to be tested, the test tank 6 is provided with a light-transmitting opening of a given angle, and the light-emitting area of ​​the flat surface light source 4 faces the light-transmitting opening;

[0048] The light energy detector 2 is arranged outside the test tank 6; the light energy detector 2 is used to receive the light emitted from the given optical entrance by moving a number of angles with a given optical entrance in the test tank 6 as the center and a given distance as the radius, and is also used to analyze the complete PST curve in the light path direction from the flat surface light source 4 to the given optical entrance and then to infinity based on the preset relationship and the received light.

[0049] In this embodiment, when the device is used:

[0050] The lens to be tested is fixed on the lens fixing member 3, and the flat surface light source 4 is arranged at the focal plane position of the lens to be tested, and the light emitting area of ​​the flat surface light source 4 emits light to the lens to be tested;

[0051] The optical entrance of the lens to be tested is a given optical entrance; the light emitted from the optical entrance of the lens to be tested is emitted from the light-transmitting opening on the test tank 6;

[0052] The light energy detector 2 is centered at the optical entrance of the lens to be tested and has a given distance as a radius, and moves at several angles to receive the light emitted from the optical entrance of the lens to be tested;

[0053] The light energy detector 2 analyzes the complete PST curve in the light path direction from the flat surface light source 4 to the given optical entrance and then to infinity according to the preset relationship and the received light, that is, the complete PST curve in the light path direction from the focal plane position to the optical entrance and then to infinity of the lens to be tested.

[0054] In this embodiment, the PST curve is analyzed (or calculated) by the light energy detector 2:

[0055] The light energy detector 2 (i.e., the detection camera) can obtain a grayscale value, which is essentially the intensity of light energy, and then the PST curve is analyzed to obtain the point source transmittance.

[0056] It should be noted that other signal processing devices may also be used to analyze the PST curve.

[0057] In this implementation manner, the lens to be tested is a lens of a space camera to be subjected to a point source transmittance test.

[0058] In the present embodiment, an optical path design opposite to that of the conventional point source transmittance test system is adopted: in the conventional point source transmittance test system, the optical path is that light from infinity is incident on the optical entrance of the lens to be tested, and finally hits the focal plane position of the lens to be tested; while the optical path in the present embodiment is opposite, that is, light is first emitted from the flat surface light source 4 at the focal plane position, and then emitted through the optical entrance of the lens to be tested according to the reversible principle of the optical path (or called the reverse light path principle), and finally received by the light energy detector 2, and then the point source transmittance is calculated according to the energy of this part of the emitted light.

[0059] In the traditional point source transmittance test system, it is necessary to simulate infinite imaging (i.e., the incidence of light at infinity), so the test device contains a collimator. At the same time, since most space cameras are large-aperture cameras and most transmission-type collimators are small-aperture, a reflective collimator is required. The reflective collimator is expensive, which can reach several million yuan, greatly increasing the test cost.

[0060] In this embodiment, the principle of reversible optical path is utilized so that the test device described in this embodiment no longer needs to simulate infinite imaging, that is, no large-aperture reflective collimator is required, which not only greatly reduces the cost of the test device, but also eliminates the interference of stray light caused by mirror scattering of the collimator, thereby greatly improving the test accuracy and test threshold of the PST test device.

[0061] In this embodiment, the additional stray light emitted by the flat surface light source 4 will be continuously reflected and absorbed by the test tank 6, thereby preventing the stray light from interfering with the test accuracy and the test threshold.

[0062] The use of the test tank 6 can effectively eliminate the light pollution caused by the flat surface light source 4 and the lens to be tested; it should be noted that the shape of the test tank 6 needs to be reasonably designed so that it can quickly guide the scattered light into the shadowless direction and quickly attenuate it. For example, a reasonable design that can be used is a double-column tank structure design.

[0063] In this embodiment, the dark room 5 is used to block external interference light.

[0064] In this embodiment, the light energy detector 2 moves around the optical entrance of the lens to be tested, and can measure the received light energy at different angles, thereby obtaining a complete PST curve in the direction of the optical path from the focal plane to the optical center and then to infinity of the lens to be tested; wherein PST is Point Source Transmittance, that is, point source transmittance.

[0065] Implementation Method 2: Combination Figure 1This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0066] The device further comprises: a guide rail 1;

[0067] The guide rail 1 is an arc-shaped guide rail, which is arranged in a darkroom 5 , and the light energy detector 2 is slidably connected to the guide rail 1 via a slider.

[0068] In this embodiment, by providing an arc-shaped guide rail and making the light energy detector 2 slidably connected to the arc-shaped guide rail, the light energy detector 2 can be moved around the center at a certain angle with a given distance as a radius, with the optical entrance of the lens to be tested as the center; thereby, the light energy detector 2 can measure the light energy values ​​at different angles, thereby obtaining a complete PST curve of the lens to be tested in the direction of the optical path from the focal plane to the optical center and then to infinity.

[0069] In this embodiment, the guide rail 1 can be a high-precision electrically controlled arc guide rail.

[0070] Implementation Method 3: Combination Figure 1 This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0071] The light energy detector 2 is a detection camera or a light meter.

[0072] In this embodiment, the light energy detector 2 is a device for measuring light energy; the detection camera and the light meter are both devices for measuring light energy.

[0073] In this embodiment, if a detection camera is used as the light energy detector 2, the detection camera itself needs to be calibrated by radiation so that it has a good linear response. At the same time, its field of view and focal length need to be reasonably designed so that it can fully cover the requirements for measuring the optical entrance of the lens to be tested.

[0074] Implementation Method 4: Combination Figure 1 This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0075] The shape and size of the light emitting area of ​​the flat surface light source 4 are consistent with the shape and size of the actual focal plane of the lens to be tested.

[0076] Implementation Method 5: Combination Figure 1This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the fourth embodiment. The specific implementation contents are as follows:

[0077] The flat surface light source 4 is a uniform radiator.

[0078] In this embodiment, by making the shape and size of the light-emitting area of ​​the flat surface light source 4 consistent with the actual focal plane of the lens to be tested, and making the flat surface light source 4 a uniform radiator, a surface light source with high stability is obtained, which minimizes the impact on the test accuracy and the test threshold; the light emitted by the surface light source is parallel, uniform and perpendicular to the lens to be tested and directed toward the lens to be tested.

[0079] Implementation Method 6: Combination Figure 1 This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0080] The visible infrared absorption rate of the darkroom 5 is above 0.95.

[0081] In this embodiment, a darkroom 5 that meets the size requirements is used, which can effectively prevent the external environment of the laboratory from interfering with the test accuracy and test threshold of the test system.

[0082] Implementation Method 7: Combination Figure 1 This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0083] The material of the darkroom 5 is matte paint or optical ultra-black coating material

[0084] In this embodiment, the introduction of the matte paint can be found at the following website:

[0085] https: / / max.book118.com / html / 2019 / 0424 / 7152041063002022.shtm.

[0086] The website contains a paper titled “Application of Matting Paint in Optical Systems at Home and Abroad”, written by Zhang Jianxian, Zou Yongjun, Xu Lei, Chen Guodun and Qing Fengling, and the corresponding institution is the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.

[0087] The paper records some matte paints with high absorption rates, such as a polyurethane black paint from the United States, NPL super black paint from the United Kingdom, and black thermal control paint from Russia, etc. These matte paints can all be used as materials for darkroom 5.

[0088] In this embodiment, the optical ultra-black coating material is specifically JS-Black Coating 01 series optical ultra-black coating material.

[0089] For an introduction to the JS-Black Coating 01 series of optical ultra-black coating materials, please refer to the following website:

[0090] http: / / www.js-mat.com / chanpin / guangxuechaoheitucengcailiao / 75.html.

[0091] Implementation Method 8: Combination Figure 1 This embodiment is described as a further limitation of the space camera point source transmittance test device based on the reverse light path principle described in the first embodiment. The specific implementation contents are as follows:

[0092] The preset relationship is:

[0093]

[0094] According to the reversible principle of optical path, E1 is the illumination of the central field of view reaching the light energy detector (2), and E2 is the illumination of the non-central field of view reaching the light energy detector 2.

[0095] Implementation Method 9: Combination Figure 1 This embodiment describes a method for testing the point source transmittance of a space camera based on the principle of reverse light path. The specific implementation contents are as follows:

[0096] The method is implemented based on the space camera point source transmittance testing device based on the reverse light path principle described in the above embodiment, and the method includes the following steps:

[0097] S1, placing the light energy detector 2 at the corresponding field of view position of the object side;

[0098] S2, fixing the lens to be tested on the lens fixing member 3, and setting the flat surface light source 4 at the focal plane position of the lens to be tested; taking the optical entrance of the lens to be tested as the given optical entrance;

[0099] S3, lighting up the flat surface light source 4;

[0100] S4, moving the light energy detector 2 with the optical entrance of the lens to be tested as the center and a given distance as the radius to receive the light emitted from the light-transmitting opening at several angles to obtain illumination data at different angles;

[0101] S5. According to the illumination data at different angles and the preset relationship, the point source transmittance of the lens to be tested in the direction of the optical path from the focal plane position to the optical entrance and then to infinity is obtained.

[0102] In this embodiment, after the flat surface light source 4 is lit, according to the principle of backlight path, the light emitted by the flat surface light source 4 (i.e., at the focal plane position of the lens to be tested) will be emitted through the lens to be tested to the optical entrance of the lens to be tested, and then emitted through the light-transmitting opening to the light energy detector 2.

[0103] In this embodiment, the object side corresponding field of view position refers to the position calculated based on the field of view angle (the field of view angle of the lens to be tested, ie, the avoidance angle) and the radius, which is the sliding position of the light energy detector 2 on the guide rail.

[0104] In this implementation manner, the point source transmittance is expressed in the form of a PST curve.

[0105] In this embodiment, the test method should be carried out after all the light shields of the space camera are installed and before the actual focal plane is installed.

[0106] In this embodiment, the installation positions of the various components of the test device need to meet the accuracy requirements; in particular, the accuracy of the installation position of the flat surface light source 4 has a great impact on the test accuracy and test threshold of the test device.

[0107] Implementation Method 10: Combination Figure 1 This embodiment is described. This embodiment is a further limitation of the method for testing the point source transmittance of a space camera based on the reverse light path principle described in Embodiment 9. The specific implementation contents are as follows:

[0108] In step S4, the light emitted from the light-transmitting opening is received by moving at several angles, and the angle step length of each movement is as follows:

[0109] If the light energy detector 2 is within the avoidance angle range, the step length of the angle of each movement of the light energy detector 2 is x, x∈[0.01°, 1°];

[0110] If the light energy detector 2 is outside the avoidance angle range, the step length of the angle of each movement of the light energy detector 2 is y, y∈[0.5°, 3°], and y>x.

[0111] In this implementation manner, the avoidance angle refers to the field of view angle of the lens to be tested.

[0112] The field of view (FOV) refers to the range of angles at which a camera (lens) can receive images in an imaging scene, and is often referred to as the field of view.

[0113] In optical instruments, the angle formed by the two edges of the maximum range of the image of the target object that can pass through the lens, with the lens of the optical instrument as the vertex, is called the field of view angle. The size of the field of view angle determines the field of view of the optical instrument. The larger the field of view angle, the larger the field of view. In layman's terms, the target object will not be included in the lens if it exceeds this angle.

[0114] In this implementation manner, for a lens to be tested with a rotationally symmetrical structure, it is sufficient to test the PST in only one direction; for a lens to be tested with an asymmetric structure, it is necessary to change the placement angle of the lens to be tested and then repeat the test.

[0115] The technical solution provided by the present invention is further described in detail above through several specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation modes described above are not intended to be used as limitations on the present invention. Any reasonable changes and improvements to the present invention, reasonable combinations of implementation modes and equivalent substitutions based on the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A space camera point source transmittance test device based on the reverse light path principle, characterized in that: The device comprises: a light energy detector (2), a flat surface light source (4), a lens fixing member to be tested (3), a darkroom (5) and a test tank (6); The light energy detector (2) and the test tank (6) are arranged inside the darkroom (5); The flat surface light source (4) and the lens fixing member (3) to be tested are arranged in the test tank (6); the lens fixing member (3) to be tested is used to fix the lens to be tested; A flat surface light source (4) is arranged at a given distance on one side of the lens fixing member (3) to be tested; On the other side of the lens fixing member (3) to be tested, the test pot (6) is provided with a light-transmitting opening of a given angle, and the light-emitting area of ​​the flat surface light source (4) faces the light-transmitting opening; The light energy detector (2) is arranged outside the test tank (6); the light energy detector (2) is used to receive light emitted from the given optical entrance by moving at a certain angle with a given distance as a radius and taking a given optical entrance in the test tank (6) as the center, and is also used to analyze a complete PST curve in the direction of the light path from the flat surface light source (4) to the given optical entrance and then to infinity according to a preset relationship and the received light; The device further comprises: a guide rail (1); The guide rail (1) is an arc-shaped guide rail, which is arranged in a dark room (5); the light energy detector (2) is slidably connected to the guide rail (1) via a slider; The shape and size of the light emitting area of ​​the flat surface light source (4) are consistent with the shape and size of the actual focal plane of the lens to be tested; The flat surface light source (4) is a uniform radiator; The darkroom (5) has a visible infrared absorption rate of greater than 0.95; The material of the darkroom (5) is matte paint or optical ultra-black coating material; The preset relationship is: According to the reversible principle of the optical path, E1 is the illumination of the central field of view reaching the light energy detector (2), and E2 is the illumination of the non-central field of view reaching the light energy detector (2); The flat surface light source (4) is arranged at the focal plane position of the lens to be tested; the light energy detector (2) is placed at the corresponding field of view position on the object side; The object side corresponding field of view position refers to the position calculated based on the field of view angle of the lens to be tested, that is, the avoidance angle and radius, which is the sliding position of the light energy detector (2) on the guide rail (1); The field of view refers to the range of angles at which a camera lens can receive images in an imaging scene, also known as the field of view.

2. The space camera point source transmittance test device based on the reverse light path principle according to claim 1 is characterized in that: The light energy detector (2) is a detection camera or a light meter.

3. A method for testing the point source transmittance of a space camera based on the principle of reverse light path, characterized in that: The method is implemented based on the device according to any one of claims 1 to 2, and the method comprises the following steps: S1, placing the light energy detector (2) at a corresponding field of view position on the object side; S2, fixing the lens to be tested on the lens fixing member (3) to be tested, and arranging the flat surface light source (4) at the focal plane position of the lens to be tested; and taking the optical entrance of the lens to be tested as the given optical entrance; S3, lighting up the flat surface light source (4); S4, moving the light energy detector (2) to a certain angle with the optical entrance of the lens to be tested as the center and a given distance as the radius to receive the light emitted from the light-transmitting opening, and obtaining illumination data at different angles; S5. According to the illumination data at different angles and the preset relationship, the point source transmittance of the lens to be tested in the direction of the optical path from the focal plane position to the optical entrance and then to infinity is obtained.

4. The method for testing the point source transmittance of a space camera based on the reverse light path principle according to claim 3, characterized in that: In step S4, the light emitted from the light-transmitting opening is received by moving at several angles, and the angle step length of each movement is as follows: If the light energy detector (2) is within the avoidance angle range, the step length of the angle of each movement of the light energy detector (2) is x, x∈[0.01°, 1°]; If the light energy detector (2) is outside the avoidance angle range, the step length of the angle of each movement of the light energy detector (2) is y, y∈[0.5°, 3°], and y>x.

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