Space camera automatic final assembly test system and method adopting transfer function

Abstract

The invention belongs to the technical field of space remote sensing space camera installation and adjustment, and provides a space camera automatic assembly test system and method adopting a transfer function in order to further improve the space camera assembly efficiency and precision, the space camera automatic assembly test system is built, and a current view field MTF real-time test is carried out. Adjusting the focusing mechanism assembly until the MTF maximum value is obtained, recording the moving step length of the corresponding focusing mechanism assembly, and switching to the next view field test; the MTF maximum values of all the set view fields are tested, a gasket repairing and grinding amount is fitted out corresponding to the positions of the mechanisms, and trimming is carried out; and retesting is carried out according to the steps, automatic final assembly and test of the camera focal plane are completed, the test efficiency and precision are improved, the measurement error is reduced, and the personnel cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace remote sensing space camera assembly and adjustment. Background Art

[0002] With the rapid development of optical technology, space cameras have been widely used in aerospace photography, becoming a key means of obtaining space information in agriculture, surveying and mapping, ocean exploration, and military reconnaissance. Space cameras consist of an optical-mechanical system and a focal plane assembly. The calibration and assembly of these two components are crucial to ensuring the quality of on-orbit imaging. The requirements for precision and efficiency in these calibration and assembly processes are becoming increasingly stringent.

[0003] Currently, the optical-mechanical system uses autocollimation to measure wavefront aberrations, adjusts the various optical components to positions that meet imaging quality requirements, and then assembles them. The focal plane assembly is mechanically or optically spliced to meet the large field of view requirements of the space camera, and finally assembled with the optical-mechanical system. The existing assembly method uses a collimator to simulate an infinitely distant target. The space camera then images the target, finds the optimal imaging position, and connects the focal plane assembly to the optical-mechanical system using gaskets. The focal plane calibration process requires precise adjustment of the collimator target position, and the focal plane must be tested for imaging conditions in at least three fields of view. This results in low testing and adjustment efficiency and high labor costs.

[0004] The MTF (transfer function) of a space camera characterizes the clarity of the camera's imaging. It includes the MTF of the optical system and the MTF of the electronic signal. The MTF of the space camera is obtained by multiplying the two. Summary of the Invention

[0005] In order to further improve the efficiency and accuracy of space camera assembly, the present invention proposes a space camera automatic assembly and testing system and method using transfer function.

[0006] On the one hand, the space camera automatic assembly and testing system using transfer function,

[0007] The focal plane assembly and focusing mechanism assembly in the space camera under test are connected and installed on the optical-mechanical system through a gasket.

[0008] An integrating sphere light source, a light pipe target adjustment mechanism, and a light pipe are sequentially placed on the side of the space camera being tested that is away from the focal plane assembly;

[0009] The stripe target is placed on the side of the light pipe target adjustment mechanism close to the light pipe and located at the focal plane of the light pipe;

[0010] The space camera under test is mounted on a two-dimensional turntable and can switch between different fields of view; the 0° field of view of the space camera under test is aligned with the optical axis of the light pipe;

[0011] The light tube target adjustment mechanism, focusing mechanism assembly, focal plane assembly and two-dimensional turntable are electrically connected to the control mechanism. The control mechanism can set the initial parameters of the camera, adjust the focusing mechanism assembly to obtain the maximum MTF value, record the movement step of the corresponding focusing mechanism assembly, and control the rotation of the two-dimensional turntable to achieve switching between different fields of view.

[0012] On the other hand, the automated assembly and testing method for a space camera using a transfer function includes the following steps:

[0013] S1. Assemble all optical components according to the space camera automated assembly and test system. Use the autocollimation test method to control the posture of the light pipe target adjustment mechanism, so that the rotating stripe target is located at the focal plane of the light pipe. After that, the light pipe target adjustment mechanism maintains the position.

[0014] S2, the integrating sphere light source illuminates the stripe target, providing an imaging target for the space camera under test;

[0015] S3. Adjust the two-dimensional turntable so that the 0° field of view of the space camera under test is aligned with the optical axis of the light pipe.

[0016] S4. After the control mechanism sets the initial parameters of the camera, it performs a real-time MTF test of the current field of view, adjusts the focus mechanism components until the MTF maximum value is obtained, records the corresponding focus mechanism component movement step, and switches to the next field of view test;

[0017] S5. Test the MTF maximum value and corresponding mechanism position of all set fields of view, complete the transfer function test, fit a gasket grinding amount based on the test results of each field of view, and perform the trimming;

[0018] S6. Reinstall the trimmed gasket and retest according to the above steps to complete the camera focal plane automated assembly and testing.

[0019] Technical effects:

[0020] This invention enables automated testing of the optomechanical system and focal plane assembly of a space camera, eliminating the need for testing three fields of view to calibrate the focal plane as in the prior art. The MTF maximum is directly obtained, and the MTF test results are used to determine the appropriate amount of spacer trimming between the focal plane assembly and the optomechanical system. The trimmed spacer is then machined to connect the optomechanical system and focal plane assembly, completing camera assembly. This testing system also enables precise adjustment of the fringe target and, using a two-dimensional turntable, enables switching between the various fields of view of the space camera. MTF testing for each field of view is integrated, improving testing efficiency and accuracy, reducing measurement errors, and reducing personnel costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the positional relationship between the test system of the present invention and the space camera under test.

[0022] Figure 2 This is a flowchart of the testing method according to an embodiment of the present invention.

[0023] Figure 3 This is a fitting diagram of the P spectrum MTF and the moving step length data of the focusing mechanism components before repair.

[0024] Figure 4 This is a fitting diagram of the P spectrum MTF after pad repair and the moving step length data of the focusing mechanism components.

[0025] Figure 5 This is a visual comparison of the focal plane position before and after padding.

[0026] Among them: 1. Integrating sphere light source, 2. Light tube target adjustment mechanism, 3. Stripe target, 4. Light tube, 5. Optical machine system, 6. Gasket, 7. Focusing mechanism assembly, 8. Focal plane assembly, 9. Two-dimensional turntable, 10. Control mechanism. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] On the one hand, this embodiment is a space camera automatic assembly and testing system using transfer function, such as Figure 1 As shown,

[0029] In the space camera under test, the focal plane assembly 8 is connected to the focusing mechanism assembly 7 and is installed on the optical-mechanical system 5 through the gasket 6. The integrating sphere light source 1, the light pipe target adjustment mechanism 2, and the light pipe 4 are placed in sequence on the side of the space camera under test away from the focal plane assembly 8; the stripe target 3 is placed on the side of the light pipe target adjustment mechanism 2 close to the light pipe and located at the focal plane of the light pipe; the space camera under test is installed on a two-dimensional turntable 9, which can switch between different fields of view; the 0° field of view of the space camera under test is aligned with the optical axis of the light pipe 4;

[0030] The light tube target adjustment mechanism 2, the focusing mechanism assembly 7, the focal plane assembly 8 and the two-dimensional turntable 9 are electrically connected to the control mechanism 10. The control mechanism 10 can set the initial parameters of the camera, adjust the focusing mechanism assembly 7 to obtain the maximum MTF value, and the corresponding moving step of the focusing mechanism assembly 7, and control the rotation of the two-dimensional turntable to achieve switching between different fields of view.

[0031] The initial camera parameters include the test field value of the tested space camera, focal plane imaging parameters, camera power-off temperature control time, and focus mechanism component test parameters and movement step length.

[0032] The light tube target adjustment mechanism 2 moves in the form of a guide rail, which can achieve translation along the optical axis or rotation around the optical axis, thereby adjusting the stripe target 3 to be located at the focal plane of the light tube.

[0033] The focusing mechanism assembly 7 is moved by a worm gear transmission, which transmits the power of the stepping motor to the lead screw through the turbine, and the lead screw is further transmitted to the slide through the nut. The focusing lens is fixed on the slide, and finally the movement of the focusing lens can be achieved.

[0034] Another aspect of this embodiment is a method for automated assembly and testing of a space camera using a transfer function, such as Figure 2 As shown, the following steps are included:

[0035] S1. Build the optical components according to the automated assembly and testing system for space cameras. Using the autocollimation test method, the control mechanism 10 controls the posture of the light pipe target adjustment mechanism 2, thereby rotating the stripe target 3 to be located at the focal plane of the light pipe 4, ensuring the relative positional relationship between the vertical direction of the stripe target 3 and the focal plane assembly. The light pipe target adjustment mechanism 2 then maintains its position.

[0036] S2, integrating sphere light source 1 illuminates stripe target 3, providing an imaging target for the space camera under test;

[0037] S3. Adjust the two-dimensional turntable 9 so that the 0° field of view of the measured space camera is aligned with the optical axis of the light pipe 4.

[0038] S4. Set the initial parameters of the control mechanism 10, perform a real-time MTF test of the current field of view, adjust the focusing mechanism assembly 7 until the MTF maximum value is obtained, record the corresponding moving step of the focusing mechanism assembly 7, and switch to the next field of view test;

[0039] S5. Test the MTF maximum value and corresponding mechanism position of all set fields of view, complete the transfer function test, fit a gasket grinding amount based on the test results of each field of view, and perform the trimming;

[0040] S6. Reinstall the trimmed gasket and retest according to the above steps to complete the camera focal plane automated assembly and testing.

[0041] Specifically in S4: the current field of view is tested for MTF, where the result of the MTF test is the product of the MTF of the optical system and the MTF of the electronic signal. The MTF value of the space camera under test is low when it is out of focus, and the focusing process is reflected in the high and low MTF value. The focal plane electronics have an imaging time, and if the time is too long, the temperature will rise and affect the test results. Therefore, if the MTF maximum value and the position of the focusing mechanism component 7 are obtained within the set temperature control time, the camera can proceed to the next field of view test. If the MTF maximum value and the position of the focusing mechanism component 7 of the space camera under test are not obtained within the temperature control time, the focal plane component is powered off, and after the temperature control time is satisfied, it is powered on again for testing until the MTF maximum value of the field of view point is measured and the position of the focusing mechanism component 7 is recorded.

[0042] The following provides a set of moving step lengths and MTF values of the focus mechanism components 7 of each field before and after the pad repair. The P spectrum number fitting diagrams in Tables 1 and 2 are as follows: Figure 3 and 4 shown.

[0043] Table 1

[0044]

[0045]

[0046] The thicknesses of the four corner points of the gasket obtained from Table 1 are 6.266 mm, 6.270 mm, 5.715 mm, and 5.719 mm.

[0047] Table 2

[0048]

[0049] The contents not described in detail in this specification belong to the existing technology known to those skilled in the art. At the same time, for those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. An automated assembly and test system for space cameras using a transfer function, wherein the focal plane assembly (8) and the focusing mechanism assembly (7) in the space camera under test are connected and then mounted on an optical-mechanical system through a gasket, characterized in that: An integrating sphere light source (1), a light pipe target adjustment mechanism (2), and a light pipe (4) are sequentially placed on a side of the space camera being tested that is away from the focal plane assembly (8); The stripe target (3) is placed on a side of the light pipe target adjustment mechanism (2) close to the light pipe (4) and located at the focal plane of the light pipe; The space camera under test is mounted on a two-dimensional turntable (9) and is capable of switching between different fields of view; the 0° field of view of the space camera under test is aligned with the optical axis of the light pipe; The light tube target adjustment mechanism (2), the focusing mechanism component (7), the focal plane component (8) and the two-dimensional turntable (9) are electrically connected to the control mechanism (10). The control mechanism (10) can set the initial parameters of the camera, adjust the focusing mechanism component (7) to obtain the maximum MTF value, record the moving step length of the corresponding focusing mechanism component (7), and control the rotation of the two-dimensional turntable (9) to achieve switching between different fields of view.

2. The space camera automated assembly and testing system using transfer function according to claim 1, characterized in that: The initial camera parameters include the test field value of the tested space camera, focal plane imaging parameters, camera power-off temperature control time, and focus mechanism component (7) test parameters and moving step length.

3. The space camera automated assembly and testing system using transfer function according to claim 1, characterized in that: The light tube target adjustment mechanism (2) is moved in a guide rail form, and can achieve translation along the optical axis or rotation around the optical axis, thereby adjusting the stripe target (3) to be located at the focal plane of the light tube.

4. The space camera automated assembly and testing system using transfer function according to claim 1, characterized in that: The focusing mechanism assembly (7) is moved by a worm gear transmission, the power of the stepping motor is transmitted to the lead screw through the turbine, and the lead screw is further transmitted to the slide through the nut, and the focusing lens is fixed on the slide, so that the movement of the focusing lens can be realized.

5. The automated assembly and testing method for space cameras using transfer functions is characterized in that: The automated assembly and testing system for a space camera according to any one of claims 1 to 4 is used, comprising the following steps: S1. Each optical element is assembled according to the space camera automated assembly and testing system. Through the self-collimation test method, the control mechanism (10) controls the posture of the light pipe target adjustment mechanism (2), so that the rotating stripe target (3) is located at the focal plane of the light pipe (4), and then the light pipe target adjustment mechanism (2) maintains the position; S2, an integrating sphere light source (1) illuminates a stripe target (3), providing an imaging target for the space camera under test; S3. Adjust the two-dimensional turntable (9) so that the 0° field of view of the space camera under test is aligned with the optical axis of the light pipe. S4, after the control mechanism (10) sets the initial parameters of the camera, it performs a real-time MTF test of the current field of view, adjusts the focusing mechanism component (7) until the MTF maximum value is obtained, records the corresponding moving step of the focusing mechanism component (7), and switches to the next field of view test; S5. Test all the set field of view MTF maximum values and corresponding mechanism positions, complete the transfer function test, fit a gasket grinding amount based on the test results of each field of view, and perform the trimming; S6. Reinstall the trimmed gasket and retest according to the above steps to complete the camera focal plane automated assembly and testing.

6. The automated assembly and testing method for a space camera using a transfer function according to claim 5, characterized in that: If the maximum MTF value and the position of the focusing mechanism component (7) are obtained within the set temperature control time, the camera can proceed to the next field of view test. If the maximum MTF value and the position of the focusing mechanism component (7) of the tested space camera are not obtained within the temperature control time, the focal plane component (8) is powered off and powered on again after the temperature control time is satisfied to perform the test until the maximum MTF value of the field of view point is measured and the position of the focusing mechanism component (7) is recorded.

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