Satellite-borne laser radar stray light test system and method

Abstract

The invention provides a spaceborne laser radar stray light testing system and method. The spaceborne laser radar stray light testing system comprises a two-dimensional satellite rotary table, a satellite body, a to-be-tested spaceborne laser radar, a two-dimensional scanning guide rail, a power meter support, an optical power meter and a solar lighting simulation system. An optical darkroom is used for simulating a space cold background, a xenon lamp large-area array light source is used for simulating sunlight, a five-degree-of-freedom scanning robot drives a scanning mirror to change the irradiation direction of the light source, and a satellite-borne laser radar is installed on a two-dimensional satellite rotary table along with a satellite body. The two-dimensional satellite turntable is matched with the five-degree-of-freedom scanning robot to realize in-orbit multi-angle solar illumination simulation; two-dimensional scanning is carried out on the position of the power meter through the two-dimensional scanning guide rail to achieve stray light power testing of the entrance pupil full aperture of the spaceborne laser radar, and stray light power distribution of the full aperture of the entrance pupil of the spaceborne laser radar is obtained through griddata function three-dimensional point interpolation complementation. And the stray light power at a radar focal plane is obtained through simulation calculation by combining Tracepro software with a radar three-dimensional model.

Description

Technical Field

[0001] This invention relates to the field of measurement and testing technology, specifically to a stray light testing system and method for spaceborne lidar. Background Technology

[0002] Spaceborne lidar detects the macroscopic and microscopic characteristics of aerosols and clouds by sensing the scattered echo signals of laser light in the atmosphere. This allows them to obtain information on atmospheric composition and content, cloud cover, and cloud phase. Because the intensity of the scattered laser echo signals is relatively weak, typically on the order of nanowatts, spaceborne lidar is highly sensitive to stray light. Solar background light is a major factor affecting lidar detection performance, and stray light radiation from the satellite surface under on-orbit illumination conditions can also cause stray light in the lidar. Therefore, it is essential to test stray light during the early design phase of both the spaceborne lidar and the satellite itself to evaluate its stray light suppression capabilities.

[0003] Current methods for testing stray light require a complete and authentic spaceborne lidar system, which is extremely costly for large-aperture spaceborne lidar systems, making it practically impossible to implement in the early design stages. Therefore, it is necessary to propose an economical and effective spaceborne lidar stray light testing system and method. Summary of the Invention

[0004] This invention addresses the problem of stray light testing for spaceborne lidar by providing a stray light testing system and method. The system includes an optical anechoic chamber, a large-area xenon lamp light source, a scanning mirror, a five-degree-of-freedom (5DOF) scanning robot, a satellite body, a spaceborne lidar, a two-dimensional satellite turntable, a two-dimensional scanning rail, a power meter, and a power meter bracket. The optical anechoic chamber simulates the cold background of space, the large-area xenon lamp light source simulates sunlight, and the five-DOF scanning robot drives the scanning mirror to change the illumination direction of the light source. The spaceborne lidar is mounted on the two-dimensional satellite turntable along with the satellite body. The two-dimensional satellite turntable and the five-DOF scanning robot work together to simulate multi-angle solar illumination in orbit. The two-dimensional scanning rail is installed inside the spaceborne lidar, and the power meter is mounted on the slider of the two-dimensional scanning rail via a power meter bracket. The photosensitive surface of the power meter is located at the entrance pupil of the spaceborne lidar. Two-dimensional scanning of the power meter's position enables the testing of stray light power across the entire aperture of the spaceborne lidar's entrance pupil. This testing system is suitable for conducting in-orbit stray light simulation testing of spaceborne lidars in the pre-research stage.

[0005] This invention provides a stray light testing system for a spaceborne lidar, comprising a two-dimensional satellite turntable, a satellite body and a spaceborne lidar under test connected sequentially to the two-dimensional satellite turntable, a two-dimensional scanning rail connected inside the spaceborne lidar under test, a power meter bracket, an optical power meter, and a solar illumination simulation system whose output light is located on the receiving optical path of the spaceborne lidar under test, all connected sequentially to the slider of the two-dimensional scanning rail. The two-dimensional satellite turntable, the satellite body, the spaceborne lidar under test, the power meter bracket, and the optical power meter are all located in an optical anechoic chamber.

[0006] An optical anechoic chamber simulates the cold background of space. The photosensitive surface of the optical power meter is located at the entrance pupil of the spaceborne lidar under test. The solar illumination simulation system performs multi-angle solar illumination simulation in the optical anechoic chamber. A two-dimensional satellite turntable drives the satellite body and the spaceborne lidar under test to rotate to change the attitude of the spaceborne lidar under test. A two-dimensional scanning guide rail drives the power meter bracket and the optical power meter to move along the X-axis or Y-axis to test the stray light power of the entrance pupil aperture of the spaceborne lidar under test.

[0007] The stray light testing system for spaceborne lidar according to the present invention, in a preferred embodiment, includes a two-dimensional scanning guide rail comprising an X-axis guide rail connected to the front end of the spaceborne lidar under test, a Y-axis guide rail slidably connected to the front end of the X-axis guide rail, a slider connected to the Y-axis guide rail, an X-axis drive motor electrically connected to the X-axis guide rail, a Y-axis drive motor electrically connected to the Y-axis guide rail, and a guide rail controller electrically connected to both the X-axis drive motor and the Y-axis drive motor. An optical power meter is connected to the front end of the slider via a power meter bracket.

[0008] The stray light testing system for spaceborne lidar described in this invention, as a preferred embodiment, further includes a control system electrically connected to both the guide rail controller and the optical power meter;

[0009] The X-axis drive motor, Y-axis drive motor, guide rail controller, and control system are all installed in a control room outside the optical darkroom, and the control system is connected to a computer.

[0010] The stray light testing system for spaceborne lidar described in this invention, as a preferred embodiment, includes a solar illumination simulation system comprising a five-degree-of-freedom scanning robot connected in an optical darkroom, a scanning mirror connected to the five-degree-of-freedom scanning robot, and a large-area xenon lamp light source located on the input optical path of the scanning mirror, with an optical power meter located on the output optical path of the scanning mirror.

[0011] A large-area xenon lamp light source simulates sunlight, and a five-degree-of-freedom scanning robot drives a scanning mirror to change the illumination direction of the large-area xenon lamp light source.

[0012] In the stray light testing system for spaceborne lidar described in this invention, as a preferred embodiment, the irradiance of the large-area xenon lamp light source is the same as the irradiance of the sunlight received by the satellite body in orbit.

[0013] The stray light testing system for spaceborne lidar described in this invention, as a preferred embodiment, uses a two-dimensional satellite turntable linked with a five-degree-of-freedom scanning robot to perform on-orbit multi-angle solar illumination simulation.

[0014] This invention provides a method for testing stray light from a spaceborne lidar, comprising the following steps:

[0015] S1. Install the two-dimensional satellite turntable, satellite body, onboard lidar to be tested, two-dimensional scanning rail, power meter bracket, optical power meter and solar illumination simulation system in the optical darkroom;

[0016] S2. Plan the test angle and light source brightness. The solar illumination simulation system simulates sunlight to irradiate and outputs it to the entrance pupil of the spaceborne lidar under test. The power meter bracket moves along the X and Y axes and records the position of the photosensitive surface of the optical power meter in real time. The optical power meter measures the optical power. Combining the position of the photosensitive surface and the optical power, the partial aperture stray light power distribution is obtained.

[0017] S3. The stray light power distribution at the entrance pupil of the spaceborne lidar is obtained by completing the stray light power distribution of part of the aperture through three-dimensional point interpolation using the griddata function.

[0018] S4. Determine whether to change the simulated sunlight angle of the solar illumination simulation system. If yes, change the test angle and return to step S2. If no, obtain the full aperture stray light power distribution at the entrance pupil of the spaceborne lidar under illumination at each angle.

[0019] S5. Input the stray light power distribution of the entire aperture at the entrance pupil of the spaceborne lidar under illumination at various angles into Tracepro software and combine it with the simulation calculation of the three-dimensional model of the spaceborne lidar under test to obtain the stray light power at the radar focal plane. A method for testing stray light of spaceborne lidar is completed.

[0020] The stray light testing method for spaceborne lidar according to the present invention, in a preferred embodiment, includes the following steps in step S3:

[0021] S31. Extract the X-coordinate of each scan point on the entire scan path to obtain the matrix Xa = [x1, x2, ..., x...]. n ];

[0022] S32. Extract the Y-coordinate of each scan point on the entire scan path to obtain the matrix Ya = [y1, y2, ..., y]. n ];

[0023] S33. Extract the stray light power value Z measured at each scanning point along the entire scanning path to obtain the matrix Za = [z1, z2, ..., z2]. n ];

[0024] S34. Within the circular aperture range of the entrance pupil of the satellite-borne lidar to be tested, interpolation points are uniformly planned. The X coordinate of the interpolation point is X = r * cos(d), and the Y coordinate is Y = r * sin(d), where r is the interpolation radius and d is the interpolation angle.

[0025] S35. Use the griddata function to interpolate the stray optical power value of the interpolation point Z = griddata(Xa,Ya,Za,X,Y,'linear'), where linear is linear interpolation;

[0026] S36. After the stray power value Z at the interpolation point is calculated, the full-aperture stray power distribution surf(X,Y,Z) at the entrance pupil of the spaceborne lidar is obtained.

[0027] The stray light testing method for spaceborne lidar described in this invention, as a preferred embodiment, includes the following steps: Step S5 involves importing a 3D model of the spaceborne lidar to be tested into Tracepro software, assigning material properties to the optical mirrors and structural materials, and establishing a radar model and a light source incident surface model based on the solar incidence angle during the experiment; assigning a value to the output light power of each light source incident surface according to the full-aperture stray light power distribution at the entrance pupil of the spaceborne lidar under illumination at various angles, and obtaining the irradiance value at the field stop of the radar telescope using the ray tracing function of Tracepro software to obtain the stray light power at the radar focal plane.

[0028] In a preferred embodiment of the stray light testing method for spaceborne lidar described in this invention, in step S1, the X-axis drive motor, Y-axis drive motor, and guide rail controller of the two-dimensional scanning guide rail are connected in a control room outside the optical darkroom.

[0029] The control system installed in the control room is electrically connected to the five-degree-of-freedom scanning robot, which includes a two-dimensional satellite turntable, a guide rail controller, an optical power meter, and a solar lighting simulation system.

[0030] In step S2, the test angle and the brightness of the solar illumination simulation system are planned based on the orbital trajectory of the satellite-borne lidar under test during its on-orbit operation. The control system controls the X-axis drive motor, Y-axis drive motor, and five-degree-of-freedom scanning robot to perform on-orbit multi-angle solar illumination simulation. At least two illumination angles are set in the areas before the satellite body enters the shadow and after it exits the shadow. A scan is performed at each angle to obtain the partial aperture stray light power distribution at the entrance pupil of the satellite-borne lidar under test under various illumination angles in the on-orbit state. The partial aperture stray light power distribution is at least 50% of the aperture stray light power distribution.

[0031] This invention enables effective simulation testing of stray light from spaceborne lidar under ground conditions while it is in orbit, and is suitable for simulating stray light from spaceborne lidar in the pre-research stage.

[0032] The present invention has the following advantages:

[0033] This invention uses an optical anechoic chamber to simulate the cold background of space, a large-area xenon lamp light source to simulate sunlight, and a five-degree-of-freedom scanning robot to drive a scanning mirror to change the illumination direction of the light source. The spaceborne lidar is mounted on a two-dimensional satellite turntable along with the satellite body. The two-dimensional satellite turntable and the five-degree-of-freedom scanning robot work together to achieve on-orbit multi-angle solar illumination simulation. A power meter is installed on a two-dimensional scanning rail inside the spaceborne lidar, with the photosensitive surface of the power meter located at the entrance pupil of the lidar. By performing a two-dimensional scan of the power meter's position, the stray light power of the entire aperture of the lidar's entrance pupil is measured. The stray light power distribution at the entrance pupil is obtained by three-dimensional point interpolation using the griddata function. Using the stray light power distribution at the entrance pupil as input, the stray light power at the radar focal plane is calculated using Tracepro software combined with a three-dimensional radar model simulation. Based on the radar's orbital trajectory during its on-orbit operation, test angles are planned to obtain the solar stray light power at the radar focal plane under various observation directions during on-orbit operation. This testing system is suitable for conducting on-orbit stray light simulation tests on spaceborne lidar in the pre-research stage. It is economical and efficient, and can effectively simulate and test stray light of spaceborne lidar in on-orbit conditions under ground conditions at a very low cost. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a stray light testing system for a spaceborne lidar.

[0035] Figure 2 This is a schematic diagram of the structure of a spaceborne lidar stray light testing system.

[0036] Figure 3 This is a schematic diagram of the location of a spaceborne lidar stray light testing system and method.

[0037] Figure 4 A map showing the location point range covered by the power meter photosensitive surface scanning of a stray light testing system and method for spaceborne lidar;

[0038] Figure 5 A stray light power distribution diagram at the entrance pupil of a spaceborne lidar, representing a stray light testing system and method for spaceborne lidar.

[0039] Figure 6 A 3D model diagram of a spaceborne lidar stray light testing system;

[0040] Figure 7 A schematic diagram of solar radiation transformation for a spaceborne lidar stray light testing system and method;

[0041] Figure 8 A schematic diagram of the solar illumination angle for a spaceborne lidar stray light testing system and method;

[0042] Figure 9 This is a flowchart of a method for testing stray light in a spaceborne lidar.

[0043] Figure label:

[0044] 1. Two-dimensional satellite turntable; 2. Satellite body; 3. Onboard lidar to be tested; 4. Two-dimensional scanning guide rail; 41. X-axis guide rail; 42. Y-axis guide rail; 43. Slider; 44. X-axis drive motor; 45. Y-axis drive motor; 46. Guide rail controller; 5. Power meter bracket; 6. Optical power meter; 7. Solar illumination simulation system; 71. Five-degree-of-freedom scanning robot; 72. Scanning mirror; 73. Xenon lamp large-area array light source; 8. Control system. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0046] Example 1

[0047] like Figures 1-5 As shown, a stray light testing system and method for spaceborne lidar are described. Figure 1 and Figure 2 As shown, the stray light testing system for spaceborne lidar includes an optical anechoic chamber, a two-dimensional satellite turntable 1, a satellite body 2, a spaceborne lidar to be tested 3, a two-dimensional scanning rail 4, a power meter bracket 5, a power meter 6, a five-degree-of-freedom scanning robot 71, a scanning mirror 72, and a large-area xenon lamp light source 73.

[0048] Optical darkrooms are used to simulate the cold background of space.

[0049] like Figure 1 As shown, the xenon lamp large-area array light source 73 is used to simulate sunlight. During the test, the radiance of the light source is consistent with the radiance of sunlight received by the satellite payload in orbit.

[0050] like Figure 1 As shown, the five-degree-of-freedom scanning robot 71 drives the scanning mirror to change the direction of the light source.

[0051] like Figure 1As shown, the spaceborne lidar 3 is mounted on a two-dimensional satellite turntable 1 along with the satellite body 2. The attitude of the spaceborne lidar 3 can be changed through the two-dimensional satellite turntable 1.

[0052] like Figure 1 As shown, the two-dimensional satellite turntable 1 works in conjunction with the five-degree-of-freedom scanning robot 71 to achieve on-orbit multi-angle solar illumination simulation.

[0053] like Figure 2 As shown, the two-dimensional scanning guide rail 4 is installed inside the spaceborne lidar 3. The power meter 6 is installed on the slider 43 of the two-dimensional scanning guide rail 4 through the power meter bracket 5. The photosensitive surface of the power meter 6 is located at the entrance pupil of the spaceborne lidar 3. By performing two-dimensional scanning through the two-dimensional guide rail 4, the stray light power of most of the aperture of the entrance pupil of the spaceborne lidar 3 can be tested by the photosensitive surface of the power meter 6.

[0054] like Figure 3 As shown, the power meter and the control system of the two-dimensional guide rail are placed in the control room, which can avoid the influence of the light from the laptop screen on the test, and also allows for convenient control of the test experiment and real-time reading of test data from the control room.

[0055] The two-dimensional guide rail 4 can be programmed to automatically and continuously scan and record the position of the photosensitive surface of the power meter in real time. The power meter 6 can record the optical power test results in real time. Combining the two, the stray light power distribution of most of the aperture at the entrance pupil of the spaceborne lidar 3 at a certain on-orbit angle can be obtained. The stray light power distribution of the entire aperture at the entrance pupil of the spaceborne lidar can be obtained by three-dimensional point interpolation completion using the griddata function. Running the scanning program once at each illumination angle can obtain the stray light power distribution of the entire aperture at the entrance pupil of the spaceborne lidar at each illumination angle, such as... Figure 5 As shown, the specific interpolation process is as follows:

[0056] 31) Extract the X coordinate of each scan point along the entire scan path to obtain a matrix.

[0057] Xa = [x1, x2, ..., xn];

[0058] 32) Extract the Y coordinate of each scan point along the entire scan path to obtain a matrix.

[0059] Ya = [y1, y2, ..., yn];

[0060] 33) Extract the stray light power value Z measured at each scanning point along the entire scanning path to obtain the matrix Za = [z1, z2, ... zn];

[0061] 34) Within the circular aperture range of the radar entrance pupil, interpolation points are uniformly planned. The X coordinate of the interpolation point is X = r * cos(d), and the Y coordinate is Y = r * sin(d), where r = 0:1:260 (i.e., from the center of the circle to the maximum radius of 260, an interpolation point is set every 1 degree), and d = 0:1:360 (i.e., from zero degrees to the maximum angle of 360, an interpolation point is set every 1 degree).

[0062] 35) Use the griddata function to interpolate and obtain the stray light power value at the interpolation point.

[0063] Z=griddata(Xa,Ya,Za,X,Y,'linear');

[0064] 36) Generate the interpolated full-aperture stray light distribution map surf(X,Y,Z).

[0065] Using the stray light power distribution across the entire aperture at the radar entrance pupil as input, the stray light power at the radar focal plane is calculated using Tracepro software in conjunction with a 3D radar model simulation. The 3D radar model is imported into the software, material properties are assigned to the optical mirrors, and black paint is assigned to the structural materials. Based on the solar incidence angle during the experiment, the radar model and the light source incident surface model are established as follows: Figure 8 As shown. Based on the laser radar entrance pupil power obtained from the experiment, the output light power of each light source incident surface was assigned a value, and the irradiance value at the radar telescope's field stop was obtained using the ray tracing function of Tracepro software. Figure 6 This is a 3D model diagram of a lidar system.

[0066] like Figure 7 As shown, solar radiation enters from the left side of the diagram, creating a shadow area on the right side of the Earth. When the satellite enters the shadow area, the solar background light has no effect on the lidar payload. When the lidar detects the Earth's atmosphere and clouds, the laser axis always points towards the Earth's surface. When the satellite is in the left half of the orbit shown in the diagram, the angle between the telescope and solar radiation exceeds 90 degrees. At this time, when the lidar telescope is facing away from solar radiation, solar radiation cannot directly enter the lidar telescope's shield. When the satellite is emerging from or about to enter the shadow, the angle between the telescope and solar radiation is less than 90 degrees, and solar radiation can directly enter the lidar telescope's shield, resulting in higher direct solar radiation power. Therefore, by setting several illumination angles in the region before and after the satellite enters or exits the shadow, and performing a scanning procedure at each angle, the stray light power distribution of most apertures at the entrance pupil of the spaceborne lidar under various illumination angles in orbit can be obtained.

[0067] Figure 8 The planned test angles were designed to incorporate the radar's trajectory during its on-orbit operation. Each face on the right side of the diagram represents a solar illumination angle.

[0068] like Figure 9 As shown, for the test procedure of each test angle, the test angle and light source brightness need to be set first, then the optical power scan within the aperture of the radar entrance pupil is performed, and then the stray light power distribution of the entire aperture of the entrance pupil is obtained by interpolation. Taking the stray light power distribution of the entire aperture of the radar entrance pupil as input, the stray light power at the radar focal plane is obtained by simulation calculation using Tracepro software combined with the radar 3D model.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A stray light testing system for spaceborne lidar, characterized in that: The system includes a two-dimensional satellite turntable (1), a satellite body (2) connected in sequence to the two-dimensional satellite turntable (1), a spaceborne lidar to be tested (3), a two-dimensional scanning guide rail (4) connected inside the spaceborne lidar to be tested (3), a power meter bracket (5), an optical power meter (6), and a solar illumination simulation system (7) whose output light is located on the receiving optical path of the spaceborne lidar to be tested (3) connected in sequence to the slider of the two-dimensional scanning guide rail (4). The two-dimensional satellite turntable (1), the satellite body (2), the spaceborne lidar to be tested (3), the power meter bracket (5), and the optical power meter (6) are all located in an optical darkroom. The optical darkroom simulates the cold background of space. The photosensitive surface of the optical power meter (6) is located at the entrance pupil of the spaceborne lidar (3) under test. The solar illumination simulation system (7) performs multi-angle solar illumination simulation in the optical darkroom. The two-dimensional satellite turntable (1) drives the satellite body (2) and the spaceborne lidar (3) under test to rotate to change the attitude of the spaceborne lidar (3) under test. The two-dimensional scanning guide rail (4) drives the power meter bracket (5) and the optical power meter (6) to move along the X-axis or Y-axis to perform stray light power testing of the entrance pupil aperture of the spaceborne lidar (3) under test.

2. The stray light testing system for spaceborne lidar according to claim 1, characterized in that: The two-dimensional scanning guide rail (4) includes an X-axis guide rail (41) connected to the front end of the internal spaceborne lidar (3) under test, a Y-axis guide rail (42) slidably connected to the front end of the X-axis guide rail (41), a slider (43) connected to the Y-axis guide rail (42), an X-axis drive motor (44) electrically connected to the X-axis guide rail (41), a Y-axis drive motor (45) electrically connected to the Y-axis guide rail (42), and a guide rail controller (46) electrically connected to both the X-axis drive motor (44) and the Y-axis drive motor (45). The optical power meter (6) is connected to the front end of the slider (43) through the power meter bracket (5).

3. The stray light testing system for spaceborne lidar according to claim 2, characterized in that: It also includes a control system (8) that is electrically connected to both the guide rail controller (46) and the optical power meter (6); The X-axis drive motor (44), the Y-axis drive motor (45), the guide rail controller (46), and the control system (8) are all installed in a control room outside the optical darkroom, and the control system (8) is connected to a computer.

4. The stray light testing system for spaceborne lidar according to claim 1, characterized in that: The solar illumination simulation system (7) includes a five-degree-of-freedom scanning robot (71) connected in the optical darkroom, a scanning mirror (72) connected to the five-degree-of-freedom scanning robot (71), and a xenon lamp large-area array light source (73) located in the input optical path of the scanning mirror (72). The optical power meter (6) is located in the output optical path of the scanning mirror (72). The xenon lamp large-area array light source (73) simulates sunlight, and the five-degree-of-freedom scanning robot (71) drives the scanning mirror (72) to change the illumination direction of the xenon lamp large-area array light source (73).

5. The stray light testing system for spaceborne lidar according to claim 4, characterized in that: The irradiance of the large-area xenon lamp light source (73) is the same as the irradiance of the solar radiation received by the satellite body (2) in orbit.

6. The stray light testing system for spaceborne lidar according to claim 4, characterized in that: The two-dimensional satellite turntable (1) is linked with the five-degree-of-freedom scanning robot (71) to perform on-orbit multi-angle solar illumination simulation.

7. A method for testing stray light from a spaceborne lidar according to any one of claims 1 to 6, characterized in that: Includes the following steps: S1. Install the two-dimensional satellite turntable (1), the satellite body (2), the onboard lidar to be tested (3), the two-dimensional scanning rail (4), the power meter bracket (5), the optical power meter (6), and the solar illumination simulation system (7) in the optical darkroom; S2. Plan the test angle and light source brightness. The solar illumination simulation system (7) simulates sunlight to irradiate and outputs it to the entrance pupil of the satellite-borne lidar (3) to be tested. The power meter bracket (5) moves along the X-axis and Y-axis and records the position of the photosensitive surface of the optical power meter (6) in real time. The optical power meter (6) measures the optical power. Combine the position of the photosensitive surface and the optical power to obtain the partial aperture stray light power distribution at the orbital angle. S3. The stray light power distribution at the entrance pupil of the spaceborne lidar is obtained by completing the partial aperture stray light power distribution through three-dimensional point interpolation using the griddata function. S4. Determine whether to change the simulated solar angle of the solar illumination simulation system (7). If yes, change the test angle and return to step S2. If no, obtain the full aperture stray light power distribution at the entrance pupil of the spaceborne lidar under illumination at each angle. S5. Input the full-aperture stray light power distribution at the entrance pupil of the spaceborne lidar under illumination at each angle into Tracepro software and combine it with the three-dimensional model simulation calculation of the spaceborne lidar (3) to be tested to obtain the stray light power at the radar focal plane. A stray light testing method for spaceborne lidar is completed.

8. The method for testing stray light in a spaceborne lidar according to claim 7, characterized in that: Step S3 includes the following steps: S31. Extract the X-coordinate of each scan point on the entire scan path to obtain the matrix Xa = [x1, x2, ..., x...]. n ]; S32. Extract the Y-coordinate of each scan point on the entire scan path to obtain the matrix Ya = [y1, y2, ..., y]. n ]; S33. Extract the stray light power value Z measured at each scanning point along the entire scanning path to obtain the matrix Za = [z1, z2, ..., z2]. n ]; S34. Within the circular aperture range of the entrance pupil of the satellite-borne lidar (3) to be tested, interpolation points are uniformly planned. The X coordinate of the interpolation point is X = r * cos(d), and the Y coordinate is Y = r * sin(d), where r is the interpolation radius and d is the interpolation angle. S35. Use the griddata function to interpolate the stray optical power value of the interpolation point Z = griddata(Xa,Ya,Za,X,Y,'linear'), where linear is linear interpolation; S36. After the stray power value Z of the interpolation point is calculated, the full aperture stray power distribution surf(X,Y,Z) at the entrance pupil of the spaceborne lidar is obtained.

9. The method for testing stray light in a spaceborne lidar according to claim 7, characterized in that: Step S5 is as follows: import the three-dimensional model of the spaceborne lidar (3) to be tested into the Tracepro software, assign material properties to the optical mirror and material properties to the structural material, and establish the radar model and the light source incident surface model according to the solar incident angle during the test; assign the output light power of each light source incident surface according to the full aperture stray light power distribution at the entrance pupil of the spaceborne lidar under the illumination of each angle, and obtain the irradiance value at the field stop of the radar telescope through the ray tracing function of the Tracepro software to obtain the stray light power at the radar focal plane.

10. A method for testing stray light in a spaceborne lidar according to claim 7, characterized in that: In step S1, the X-axis drive motor (44), Y-axis drive motor (45), and guide rail controller (46) of the two-dimensional scanning guide rail (4) are connected to the control room outside the optical dark room; The control system (8) installed in the control room is electrically connected to the two-dimensional satellite turntable (1), the rail controller (46), the optical power meter (6), the five-degree-of-freedom scanning robot (71) of the solar lighting simulation system (7); In step S2, the test angle is planned and the brightness of the solar illumination simulation system (7) is planned in combination with the orbital trajectory of the satellite-borne lidar (3) under test during its on-orbit operation; the control system (8) controls the X-axis drive motor (44), the Y-axis drive motor (45), and the five-degree-of-freedom scanning robot (71) to perform on-orbit multi-angle solar illumination simulation; at least two illumination angles are set in the area before the satellite body (2) enters the shadow and after it exits the shadow, and a scan is performed at each angle to obtain the partial aperture stray light power distribution at the entrance pupil of the satellite-borne lidar (3) under each illumination angle in the on-orbit state, and the partial aperture stray light power distribution is at least 50% of the aperture stray light power distribution.

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