Space camera body dimensional stability testing device and testing method

Abstract

The present invention relates to the field of space remote sensing, and in particular to a space camera body size stability test device and test method, the test device comprises a space camera body size stability test device, the body comprises a load-bearing cylinder and a front frame and a rear frame fixed at both ends of the load-bearing cylinder, the test device comprises a laser, a front optical path, six measuring arms, a test board, and a data acquisition system, the six measuring arms are divided into two groups and are evenly distributed on the front frame and the rear frame along the circumferential direction; the laser emitted by the laser enters the six measuring arms respectively through the front optical path, the laser is connected to the test board through an optical fiber, the six measuring arms are connected to the test board through an optical fiber, and the test board is connected to the data acquisition system through a data line. The present invention has the advantages of high precision, small size, light weight, convenient integration, real-time measurement, etc., and an optical engineer can make appropriate corrections to the current control measures according to the test results to ensure that the body size stability meets the optical tolerance requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of space remote sensing, and in particular relates to a device and a method for testing the dimensional stability of a space camera body. Background Art

[0002] With the continuous development of aerospace technology, space cameras are playing an increasingly important role in the fields of earth observation and astronomical exploration. The fuselage is the skeleton of the space camera, which is used to ensure the stable and reliable spatial position relationship of each optical component. Its dimensional accuracy and stability directly affect the performance of the optical system. The optical components of the space camera have extremely stringent requirements on the on-orbit stability tolerance, which requires that the fuselage should not only have good strength and stiffness, but also have good stability. At present, space cameras generally use high-modulus carbon fiber composite materials with low density, high modulus, high tensile strength, and designable linear expansion coefficient as the fuselage material to ensure its gravity adaptability and thermal adaptability.

[0003] In the prior art, the dimensional stability tolerance of the fuselage is generally obtained based on the stability tolerance requirements provided by the optical design, and then the temperature control index of the fuselage is obtained. Then, through thermal design and mechanical and thermal simulation, the active and passive thermal control schemes of the fuselage are determined, and thermal implementation is carried out accordingly. However, due to factors such as fuselage manufacturing and assembly errors, stress release, vacuum degassing of carbon fiber materials, non-uniformity of thermal control multilayer materials, and errors in the thermoelectric performance of heaters, the actual fuselage dimensional stability is different from the theoretical model. This difference cannot be accurately quantified through ground thermal vacuum and thermal optical tests, and it is also impossible to accurately predict the on-orbit dimensional stability of the optical elements of the space camera.

[0004] Therefore, there is an urgent need for a method to measure the dimensional stability of a space camera body on the ground. Summary of the invention

[0005] In view of this, the present invention aims to provide a space camera body dimensional stability testing device and testing method to solve the problem of low accuracy in existing body dimensional stability testing.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] A space camera fuselage dimensional stability testing device, comprising a space camera fuselage dimensional stability testing device, the fuselage comprises a load-bearing cylinder and a front frame and a rear frame fixed at both ends of the load-bearing cylinder, the testing device comprises a laser, a front optical path, a first measuring arm of the front frame, a second measuring arm of the front frame, a third measuring arm of the front frame, a first measuring arm of the rear frame, a second measuring arm of the rear frame, a third measuring arm of the rear frame, a testing board, and a data acquisition system; wherein,

[0008] The laser emitted by the laser enters the first measuring arm of the front frame, the second measuring arm of the front frame, the third measuring arm of the front frame, the first measuring arm of the rear frame, the second measuring arm of the rear frame, and the third measuring arm of the rear frame respectively through the front optical path. The first measuring arm of the front frame, the second measuring arm of the front frame, and the third measuring arm of the front frame are evenly distributed on the front frame along the circumferential direction, and the first measuring arm of the rear frame, the second measuring arm of the rear frame, and the third measuring arm of the rear frame are evenly distributed on the rear frame along the circumferential direction;

[0009] The laser is connected to the test board through optical fiber, the first measuring arm of the front frame, the second measuring arm of the front frame, the third measuring arm of the front frame, the first measuring arm of the rear frame, the second measuring arm of the rear frame, and the third measuring arm of the rear frame are respectively connected to the test board through optical fiber, and the test board is connected to the data acquisition system through a data cable.

[0010] Further, the front optical path includes a first beam splitter, a second beam splitter, a first folding mirror, a third beam splitter, a fourth beam splitter, a second folding mirror, a third folding mirror, a fifth beam splitter and a fourth folding mirror; wherein,

[0011] The second beam splitter is arranged in the reflection direction of the first beam splitter, the first measuring arm of the front frame is arranged in the reflection direction of the second beam splitter, the first folding mirror is arranged in the transmission direction of the second beam splitter, the first measuring arm of the rear frame is arranged in the reflection direction of the first folding mirror, the third beam splitter is arranged in the transmission direction of the first beam splitter, the fourth beam splitter is arranged in the reflection direction of the third beam splitter, the second measuring arm of the front frame is arranged in the reflection direction of the fourth beam splitter, the second folding mirror is arranged in the transmission direction of the fourth beam splitter, the second measuring arm of the rear frame is arranged in the reflection direction of the second folding mirror, the third folding mirror is arranged in the transmission direction of the third beam splitter, the fifth beam splitter is arranged in the reflection direction of the third folding mirror, the third measuring arm of the front frame is arranged in the reflection direction of the fifth beam splitter, the fourth folding mirror is arranged in the transmission direction of the fifth beam splitter, and the third measuring arm of the rear frame is arranged in the reflection direction of the fourth folding mirror.

[0012] Furthermore, the first measuring arm of the front frame includes a first dual-frequency laser interferometer and a first target mirror of the front frame, the second measuring arm of the front frame includes a second dual-frequency laser interferometer and a second target mirror of the front frame, the third measuring arm of the front frame includes a third dual-frequency laser interferometer and a third target mirror of the front frame, the first measuring arm of the rear frame includes a fourth dual-frequency laser interferometer and a first target mirror of the rear frame, the second measuring arm of the rear frame includes a fifth dual-frequency laser interferometer and a second target mirror of the rear frame, the third measuring arm of the rear frame includes a sixth dual-frequency laser interferometer and a third target mirror of the rear frame, and the first dual-frequency laser interferometer, the second dual-frequency laser interferometer, the third dual-frequency laser interferometer, the fourth dual-frequency laser interferometer, the fifth dual-frequency laser interferometer, and the sixth dual-frequency laser interferometer are respectively connected to the test board through optical fibers.

[0013] Furthermore, the first target mirror of the front frame, the second target mirror of the front frame and the third target mirror of the front frame are evenly distributed on the front frame along the circumferential direction, and the first target mirror of the front frame, the second target mirror of the front frame and the third target mirror of the front frame form a plane; the first target mirror of the rear frame, the second target mirror of the rear frame and the third target mirror of the rear frame are evenly distributed on the rear frame along the circumferential direction, and the first target mirror of the rear frame, the second target mirror of the rear frame and the third target mirror of the rear frame form a plane.

[0014] Furthermore, the first folding mirror, the second folding mirror, the third folding mirror and the fourth folding mirror are all plane reflecting mirrors.

[0015] Furthermore, the light energy deviation ratio between any two measuring arms among the first measuring arm of the front frame, the second measuring arm of the front frame, the third measuring arm of the front frame, the first measuring arm of the rear frame, the second measuring arm of the rear frame and the third measuring arm of the rear frame is less than or equal to 5%.

[0016] Furthermore, the laser is a dual-frequency HeNe laser.

[0017] A method for testing the dimensional stability of a space camera body is implemented using the above-mentioned device for testing the dimensional stability of a space camera body, including measuring the translation amount of a front frame, measuring the translation amount of a rear frame, measuring the tilt amount of a front frame, and measuring the tilt amount of a rear frame; wherein:

[0018] The translation measurement of the front frame includes:

[0019] The laser emitted by the laser enters the first measuring arm, the second measuring arm and the third measuring arm of the front frame through the front optical path. The interference light signals generated by the first measuring arm, the second measuring arm and the third measuring arm of the front frame are respectively transmitted to the test board, converted into digital signals and transmitted to the data acquisition system. The displacement changes of the three measuring positions on the front frame are obtained through calculation. , for the three displacement changes Calculate the translation of the front frame :

[0020] ;

[0021] The translation measurement of the rear frame includes:

[0022] The laser emitted by the laser enters the first measuring arm, the second measuring arm and the third measuring arm of the rear frame through the front optical path. The interference light signals generated by the first measuring arm, the second measuring arm and the third measuring arm of the rear frame are respectively transmitted to the test board, converted into digital signals and transmitted to the data acquisition system. The displacement changes of the three measuring positions on the rear frame are obtained through calculation. , for the three displacement changes Calculate the translation of the rear frame :

[0023] ;

[0024] The tilt measurement of the front frame includes pitch angle measurement and yaw angle measurement. Assume that the distribution circle diameters of the first measuring arm, the second measuring arm and the third measuring arm of the front frame are ,but:

[0025] The pitch angle measurement of the front frame includes:

[0026] Distribution circle diameter and displacement change Calculate the pitch angle of the front frame :

[0027] ;

[0028] The yaw angle measurement of the front frame includes:

[0029] Distribution circle diameter and displacement change Calculate the torsion angle of the front frame :

[0030] ;

[0031] The tilt measurement of the rear frame includes pitch angle measurement and yaw angle measurement. Suppose the distribution circle diameters of the first target mirror of the rear frame, the second target mirror of the rear frame, and the third target mirror of the rear frame are ,but:

[0032] The pitch angle measurement of the rear frame includes:

[0033] Distribution circle diameter and displacement change Calculate the pitch angle of the rear frame :

[0034] ;

[0035] The rear frame yaw angle measurement includes:

[0036] Distribution circle diameter and displacement change Calculate the torsion angle of the front frame :

[0037] .

[0038] Furthermore, according to the translation of the front frame and the translation of the rear frame Calculate the translation of the front frame relative to the rear frame :

[0039] ;

[0040] According to the pitch angle of the front frame and the pitch angle of the rear frame Calculate the pitch angle of the front frame relative to the rear frame :

[0041] ;

[0042] According to the torsion angle of the front frame and the yaw angle of the rear frame Calculate the yaw angle of the front frame relative to the rear frame :

[0043] .

[0044] Further, the front optical path includes a first beam splitter, a second beam splitter, a first folding mirror, a third beam splitter, a fourth beam splitter, a second folding mirror, a third folding mirror, a fifth beam splitter and a fourth folding mirror;

[0045] The first measuring arm of the front frame includes a first dual-frequency laser interferometer and a first target mirror of the front frame, the second measuring arm of the front frame includes a second dual-frequency laser interferometer and a second target mirror of the front frame, the third measuring arm of the front frame includes a third dual-frequency laser interferometer and a third target mirror of the front frame, the first measuring arm of the rear frame includes a fourth dual-frequency laser interferometer and a first target mirror of the rear frame, the second measuring arm of the rear frame includes a fifth dual-frequency laser interferometer and a second target mirror of the rear frame, and the third measuring arm of the rear frame includes a sixth dual-frequency laser interferometer and a third target mirror of the rear frame;

[0046] The laser emitted by the laser enters the first measuring arm of the front frame after being reflected by the first beam splitter and the second beam splitter, and is divided into reference light and test light by the first dual-frequency laser interferometer. After the test light reaches the first target mirror of the front frame, it is reflected by the first target mirror of the front frame and returns to the first dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the first target mirror of the front frame. ;

[0047] The laser emitted by the laser enters the second measuring arm of the front frame through transmission of the first beam splitter, reflection of the third beam splitter, and reflection of the fourth beam splitter, and is divided into reference light and test light by the second dual-frequency laser interferometer. After the test light reaches the second target mirror of the front frame, it is reflected by the second target mirror of the front frame and returns to the second dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the second target mirror of the front frame. ;

[0048] The laser emitted by the laser enters the third measuring arm of the front frame after being transmitted by the first beam splitter, the third beam splitter, the third folding mirror, and the fifth beam splitter, and is divided into reference light and test light by the third dual-frequency laser interferometer. After the test light reaches the third target mirror of the front frame, it is reflected by the third target mirror of the front frame and returns to the third dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the third target mirror of the front frame. ;

[0049] The laser emitted by the laser enters the first measuring arm of the rear frame after being reflected by the first beam splitter, transmitted by the second beam splitter, and reflected by the first folding mirror, and is divided into reference light and test light by the fourth dual-frequency laser interferometer. After the test light reaches the first target mirror of the rear frame, it is reflected by the first target mirror of the rear frame and returns to the fourth dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the first target mirror of the rear frame. ;

[0050] The laser emitted by the laser enters the second measuring arm of the rear frame through transmission of the first beam splitter, reflection of the third beam splitter, transmission of the fourth beam splitter, and reflection of the second folding mirror, and is divided into reference light and test light by the fifth dual-frequency laser interferometer. After the test light reaches the second target mirror of the rear frame, it is reflected by the second target mirror of the rear frame and returns to the fifth dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the second target mirror of the rear frame. ;

[0051] The laser emitted by the laser enters the third measuring arm of the rear frame after being transmitted by the first beam splitter, the third beam splitter, the third folding mirror, the fifth beam splitter, and the fourth folding mirror, and is divided into reference light and test light by the sixth dual-frequency laser interferometer. After the test light reaches the third target mirror of the rear frame, it is reflected by the third target mirror of the rear frame and returns to the sixth dual-frequency laser interferometer, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board and converted into a digital signal, and then transmitted to the data acquisition system to collect the displacement change of the third target mirror of the rear frame. .

[0052] Compared with the prior art, the invention can achieve the following beneficial effects:

[0053] The present invention adopts a dual-frequency laser interferometer to measure the displacement of the target mirror in each measuring arm, and then uses a solution method to calculate the translation and tilt of the front frame of the space camera body relative to the rear frame, which can realize high-precision test of the dimensional stability of the large space camera body. It has the advantages of high precision, small size, light weight, convenient integration, real-time measurement, etc. Optical and mechanical engineers can make appropriate corrections to the current control measures according to the test results to ensure that the dimensional stability of the body meets the optical tolerance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0055] Figure 1 is a schematic diagram of the structure of a space camera body according to an embodiment of the invention;

[0056] Figure 2 It is a schematic diagram of the installation position of the space camera body size stability testing device according to the embodiment of the invention on the space camera body;

[0057] Figure 3 It is a structural schematic diagram of a space camera body size stability testing device according to an embodiment of the invention;

[0058] Figure 4 It is a schematic diagram of the structure of the front optical path according to the embodiment of the invention;

[0059] Figure 5 is a schematic structural diagram of the first measuring arm of the front frame according to an embodiment of the invention;

[0060] Figure 6 is a schematic structural diagram of the second measuring arm of the front frame according to an embodiment of the invention;

[0061] Figure 7 is a schematic structural diagram of the third measuring arm of the front frame according to an embodiment of the invention;

[0062] Figure 8 is a schematic structural diagram of the first measuring arm of the rear frame according to an embodiment of the invention;

[0063] Fig. 9 is a schematic structural diagram of the second measuring arm of the rear frame according to an embodiment of the invention;

[0064] Fig.10 is a schematic structural diagram of the third measuring arm of the rear frame according to an embodiment of the invention;

[0065] Fig.11 is a schematic diagram of the pitch angles of the front frame and the rear frame according to an embodiment of the invention;

[0066] Fig.12 It is a schematic diagram of the torsion and swing angles of the front frame and the rear frame according to the embodiment of the invention.

[0067] The accompanying drawings include: laser 1, front optical path 2, first measuring arm 3 of front frame, second measuring arm 4 of front frame, third measuring arm 5 of front frame, first measuring arm 6 of rear frame, second measuring arm 7 of rear frame, third measuring arm 8 of rear frame, test board 9, data acquisition system 10, load-bearing cylinder 11, front frame 12, rear frame 13, first beam splitter 2-1, second beam splitter 2-2, first folding mirror 2-3, third beam splitter 2-4, fourth beam splitter 2-5, second folding mirror 2-6, first Three folding mirrors 2-7, the fifth spectrometer 2-8, the fourth folding mirror 2-9, the first dual-frequency laser interferometer 3-1, the first target mirror 3-2 of the front frame, the second dual-frequency laser interferometer 4-1, the second target mirror 4-2 of the front frame, the third dual-frequency laser interferometer 5-1, the third target mirror 5-2 of the front frame, the fourth dual-frequency laser interferometer 6-1, the first target mirror 6-2 of the rear frame, the fifth dual-frequency laser interferometer 7-1, the second target mirror 7-2 of the rear frame, the sixth dual-frequency laser interferometer 8-1, and the third target mirror 8-2 of the rear frame. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0069] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0070] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0071] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0072] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0073] like Figure 1-Figure 3 As shown, an embodiment of the present invention provides a space camera body size stability testing device for testing the size stability of a space camera body. The space camera body includes a load-bearing cylinder 11 and a front frame 12 and a rear frame 13 fixed at both ends of the load-bearing cylinder 11.

[0074] The space camera body size stability testing device includes a laser 1, a front optical path 2, a front frame first measuring arm 3, a front frame second measuring arm 4, a front frame third measuring arm 5, a rear frame first measuring arm 6, a rear frame second measuring arm 7, a rear frame third measuring arm 8, a test board 9, and a data acquisition system 10; wherein the laser 1 is connected to the test board 9 through an optical fiber, the front frame first measuring arm 3, the front frame second measuring arm 4, the front frame third measuring arm 5, the rear frame first measuring arm 6, the rear frame second measuring arm 7, and the rear frame third measuring arm 8 are respectively connected to the test board 9 through optical fibers, and the test board 9 is connected to the data acquisition system 10 through a data line.

[0075] The front frame first measuring arm 3, the front frame second measuring arm 4 and the front frame third measuring arm 5 are evenly distributed on the front frame 12 along the circumferential direction, and the rear frame first measuring arm 6, the rear frame second measuring arm 7 and the rear frame third measuring arm 8 are evenly distributed on the rear frame 13 along the circumferential direction.

[0076] The laser emitted by the laser 1 enters the front frame first measuring arm 3, the front frame second measuring arm 4, the front frame third measuring arm 5, the rear frame first measuring arm 6, the rear frame second measuring arm 7, and the rear frame third measuring arm 8 through the front optical path 2.

[0077] like Figure 4 As shown, the front optical path 2 includes a first beam splitter 2-1, a second beam splitter 2-2, a first folding mirror 2-3, a third beam splitter 2-4, a fourth beam splitter 2-5, a second folding mirror 2-6, a third folding mirror 2-7, a fifth beam splitter 2-8 and a fourth folding mirror 2-9; wherein the second beam splitter 2-2 is arranged in the reflection direction of the first beam splitter 2-1, the first measuring arm 3 of the front frame is arranged in the reflection direction of the second beam splitter 2-2, the first folding mirror 2-3 is arranged in the transmission direction of the second beam splitter 2-2, the first measuring arm 6 of the rear frame is arranged in the reflection direction of the first folding mirror 2-3, the third beam splitter 2-4 is arranged in the transmission direction of the first beam splitter 2-1, and the fourth beam splitter 2-5 is arranged in the transmission direction of the first beam splitter 2-1. -5 is set in the reflection direction of the third beam splitter 2-4, the second measuring arm 4 of the front frame is set in the reflection direction of the fourth beam splitter 2-5, the second folding mirror 2-6 is set in the transmission direction of the fourth beam splitter 2-5, the second measuring arm 7 of the rear frame is set in the reflection direction of the second folding mirror 2-6, the third folding mirror 2-7 is set in the transmission direction of the third beam splitter 2-4, the fifth beam splitter 2-8 is set in the reflection direction of the third folding mirror 2-7, the third measuring arm 5 of the front frame is set in the reflection direction of the fifth beam splitter 2-8, the fourth folding mirror 2-9 is set in the transmission direction of the fifth beam splitter 2-8, and the third measuring arm 8 of the rear frame is set in the reflection direction of the fourth folding mirror 2-9.

[0078] like Figure 5 As shown, the first measuring arm 3 of the front frame includes a first dual-frequency laser interferometer 3-1 and a first target mirror 3-2 of the front frame. The first dual-frequency laser interferometer 3-1 and the first target mirror 3-2 of the front frame are sequentially arranged in the reflection direction of the second beam splitter 2-2. The first dual-frequency laser interferometer 3-1 is closer to the second beam splitter 2-2 than the first target mirror 3-2 of the front frame.

[0079] like Figure 6As shown, the second measuring arm 4 of the front frame includes a second dual-frequency laser interferometer 4-1 and a second target mirror 4-2 of the front frame. The second dual-frequency laser interferometer 4-1 and the second target mirror 4-2 of the front frame are sequentially arranged in the reflection direction of the fourth beam splitter 2-5. The second dual-frequency laser interferometer 4-1 is closer to the fourth beam splitter 2-5 than the second target mirror 4-2 of the front frame.

[0080] like Figure 7 As shown, the third measuring arm 5 of the front frame includes a third dual-frequency laser interferometer 5-1 and a third target mirror 5-2 of the front frame. The third dual-frequency laser interferometer 5-1 and the third target mirror 5-2 of the front frame are sequentially arranged in the reflection direction of the fifth beam splitter 2-8. The third dual-frequency laser interferometer 5-1 is closer to the fifth beam splitter 2-8 than the third target mirror 5-2 of the front frame.

[0081] like Figure 8 As shown, the first measuring arm 6 of the rear frame includes a fourth dual-frequency laser interferometer 6-1 and a first target mirror 6-2 of the rear frame. The fourth dual-frequency laser interferometer 6-1 and the first target mirror 6-2 of the rear frame are sequentially arranged in the reflection direction of the first folding mirror 2-3. The fourth dual-frequency laser interferometer 6-1 is closer to the first folding mirror 2-3 than the first target mirror 6-2 of the rear frame.

[0082] like Fig. 9 As shown, the second measuring arm 7 of the rear frame includes a fifth dual-frequency laser interferometer 7-1 and a second target mirror 7-2 of the rear frame. The fifth dual-frequency laser interferometer 7-1 and the second target mirror 7-2 of the rear frame are sequentially arranged in the reflection direction of the second folding mirror 2-6. The fifth dual-frequency laser interferometer 7-1 is closer to the second folding mirror 2-6 than the second target mirror 7-2 of the rear frame.

[0083] like Fig.10 As shown, the third measuring arm 8 of the rear frame includes a sixth dual-frequency laser interferometer 8-1 and a third target mirror 8-2 of the rear frame. The sixth dual-frequency laser interferometer 8-1 and the third target mirror 8-2 of the rear frame are sequentially arranged in the reflection direction of the fourth folding mirror 2-9. The sixth dual-frequency laser interferometer 8-1 is closer to the fourth folding mirror 2-9 than the third target mirror 8-2 of the rear frame.

[0084] Combination Figure 1-Figure 10 The first target mirror 3-2 of the front frame, the second target mirror 4-2 of the front frame and the third target mirror 5-2 of the front frame are evenly distributed on the front frame 12 along the circumferential direction, and the first target mirror 3-2 of the front frame, the second target mirror 4-2 of the front frame and the third target mirror 5-2 of the front frame form a plane; the first target mirror 6-2 of the rear frame, the second target mirror 7-2 of the rear frame and the third target mirror 8-2 of the rear frame are evenly distributed on the rear frame 13 along the circumferential direction, and the first target mirror 6-2 of the rear frame, the second target mirror 7-2 of the rear frame and the third target mirror 8-2 of the rear frame form a plane.

[0085] In a specific embodiment, the laser 1 includes but is not limited to a highly stable dual-frequency HeNe laser; the first folding mirror 2-3, the second folding mirror 2-6, the third folding mirror 2-7, the fourth folding mirror 2-9, the first target mirror 3-2 of the front frame, the second target mirror 4-2 of the front frame, the third target mirror 5-2 of the front frame, the first target mirror 6-2 of the rear frame, the second target mirror 7-2 of the rear frame and the third target mirror 8-2 of the rear frame are all plane reflectors; the light energy deviation between any two measuring arms of the front frame first measuring arm 3, the front frame second measuring arm 4, the front frame third measuring arm 5, the rear frame first measuring arm 6, the rear frame second measuring arm 7 and the rear frame third measuring arm 8 accounts for The ratio is less than or equal to 5%, and the light energy deviation between each measuring arm is minimized. For example, the first beam splitter 2-1 is a 33% beam splitter (33% reflection, 67% transmission), the second beam splitter 2-2, the third beam splitter 2-4, the fourth beam splitter 2-5, and the fifth beam splitter 2-8 are all 50% beam splitters. The light energy proportions of the six measuring arms are: the first measuring arm 3 of the front frame is 16.5%, the second measuring arm 4 of the front frame is 16.75%, the third measuring arm 5 of the front frame is 16.75%, the first measuring arm 6 of the rear frame is 16.5%, the second measuring arm 7 of the rear frame is 16.75%, and the third measuring arm 8 of the rear frame is 16.75%.

[0086] The above content describes in detail the space camera body size stability testing device provided by the embodiment of the present invention. Corresponding to the measuring device, the embodiment of the present invention also provides a space camera body size stability testing method, which is implemented using the above-mentioned space camera body size stability testing device.

[0087] Combination Figure 1-Figure 12 As shown, the space camera body size stability testing method provided by the embodiment of the present invention includes the translation and tilt measurement of the front frame 12, the translation and tilt measurement of the rear frame 13, the tilt measurement of the front frame 12 and the rear frame 13 includes the pitch angle measurement and the yaw angle measurement, the translation refers to the displacement of the frame (including the front frame 12 and the rear frame 13) along the axial direction, the pitch angle refers to the angle between the plumb line of the frame and the tilt direction of the frame, and the yaw angle refers to the angle between the tilt direction of the frame and the horizontal direction, which are described in detail below.

[0088] 1. Measurement of the translation amount of the front frame 12

[0089] The laser emitted by the laser 1 enters the first measuring arm 3 of the front frame after being reflected by the first beam splitter 2-1 and the second beam splitter 2-2, and is divided into reference light and test light by the first dual-frequency laser interferometer 3-1. After the test light reaches the first target mirror 3-2 of the front frame, it is reflected by the first target mirror 3-2 of the front frame and returns to the first dual-frequency laser interferometer 3-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the first target mirror 3-2 of the front frame. .

[0090] The laser emitted by the laser 1 enters the second measuring arm 4 of the front frame through the transmission of the first beam splitter 2-1, the reflection of the third beam splitter 2-4, and the reflection of the fourth beam splitter 2-5, and is divided into reference light and test light by the second dual-frequency laser interferometer 4-1. After the test light reaches the second target mirror 4-2 of the front frame, it is reflected by the second target mirror 4-2 of the front frame and returns to the second dual-frequency laser interferometer 4-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the second target mirror 4-2 of the front frame. .

[0091] The laser emitted by the laser 1 enters the third measuring arm 5 of the front frame after being transmitted by the first beam splitter 2-1, the third beam splitter 2-4, the third folding mirror 2-7, and the fifth beam splitter 2-8, and is divided into reference light and test light by the third dual-frequency laser interferometer 5-1. After the test light reaches the third target mirror 5-2 of the front frame, it is reflected by the third target mirror 5-2 of the front frame and returns to the third dual-frequency laser interferometer 5-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the third target mirror 5-2 of the front frame. .

[0092] The displacement change of the first target mirror 3-2 of the front frame , displacement change of the second target mirror 4-2 of the front frame , the displacement change of the third target mirror 5-2 of the front frame Calculate the translation amount of the front frame 12 :

[0093] .

[0094] 2. Measurement of the translation amount of the rear frame 13

[0095] The laser emitted by the laser 1 enters the first measuring arm 6 of the rear frame after being reflected by the first beam splitter 2-1, transmitted by the second beam splitter 2-2, and reflected by the first folding mirror 2-3, and is divided into reference light and test light by the fourth dual-frequency laser interferometer 6-1. After the test light reaches the first target mirror 6-2 of the rear frame, it is reflected by the first target mirror 6-2 of the rear frame and returns to the fourth dual-frequency laser interferometer 6-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the first target mirror 6-2 of the rear frame. .

[0096] The laser emitted by the laser 1 enters the second measuring arm 7 of the rear frame through the transmission of the first beam splitter 2-1, the reflection of the third beam splitter 2-4, the transmission of the fourth beam splitter 2-5, and the reflection of the second folding mirror 2-6, and is divided into reference light and test light by the fifth dual-frequency laser interferometer 7-1. After the test light reaches the second target mirror 7-2 of the rear frame, it is reflected by the second target mirror 7-2 of the rear frame and returns to the fifth dual-frequency laser interferometer 7-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the second target mirror 7-2 of the rear frame. .

[0097] The laser emitted by the laser 1 enters the third measuring arm 8 of the rear frame after being transmitted by the first beam splitter 2-1, the third beam splitter 2-4, the third folding mirror 2-7, the fifth beam splitter 2-8, and the fourth folding mirror 2-9, and is divided into reference light and test light by the sixth dual-frequency laser interferometer 8-1. After the test light reaches the third target mirror 8-2 of the rear frame, it is reflected by the third target mirror 8-2 of the rear frame and returns to the sixth dual-frequency laser interferometer 8-1, and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board 9 and converted into a digital signal, and then transmitted to the data acquisition system 10 to collect the displacement change of the third target mirror 8-2 of the rear frame. .

[0098] The displacement change of the first target mirror 6-2 of the rear frame , the displacement change of the second target mirror 7-2 of the rear frame , the displacement change of the third target mirror 8-2 of the rear frame Calculate the translation amount of the rear frame 13 :

[0099] .

[0100] 3. Pitch Angle Measurement of Front Frame 12

[0101] Assume that the distribution circle diameters of the first measuring arm 3 of the front frame, the second measuring arm 4 of the front frame and the third measuring arm 5 of the front frame are , then the distribution circle diameter and displacement change Calculate and obtain the pitch angle of the front frame 12 :

[0102] .

[0103] 4. Measurement of the torsion angle of the front frame 12

[0104] Distribution circle diameter and displacement change Calculate the torsion angle of the front frame 12 :

[0105] .

[0106] 5. Pitch Angle Measurement of Rear Frame 13

[0107] Assume that the distribution circle diameters of the first target mirror 6-2 of the rear frame, the second target mirror 7-2 of the rear frame, and the third target mirror 8-2 of the rear frame are , then the distribution circle diameter and displacement change Calculate the pitch angle of the rear frame 13 :

[0108] .

[0109] VI. Measurement of the torsion angle of the rear frame 13

[0110] Distribution circle diameter and displacement change The torsion angle of the front frame 12 is calculated :

[0111] .

[0112] According to the translation amount of the front frame 12 and the translation amount of the rear frame 13 Calculate the translation of the front frame 12 relative to the rear frame 13 :

[0113] .

[0114] According to the pitch angle of the front frame 12 and the pitch angle of the rear frame 13 Calculate the pitch angle of the front frame 12 relative to the rear frame 13 :

[0115] .

[0116] According to the torsion angle of the front frame 12 and the torsion angle of the rear frame 13 Calculate the torsion angle of the front frame 12 relative to the rear frame 13 :

[0117] .

[0118] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0119] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for testing the dimensional stability of a space camera body, the body comprising a load-bearing cylinder (11) and a front frame (12) and a rear frame (13) fixed at both ends of the load-bearing cylinder, characterized in that: The testing device comprises a laser (1), a front optical path (2), a first measuring arm of a front frame (3), a second measuring arm of a front frame (4), a third measuring arm of a front frame (5), a first measuring arm of a rear frame (6), a second measuring arm of a rear frame (7), a third measuring arm of a rear frame (8), a testing board (9), and a data acquisition system (10); wherein: Laser light emitted by the laser (1) enters the first measuring arm (3) of the front frame, the second measuring arm (4) of the front frame, the third measuring arm (5) of the front frame, the first measuring arm (6) of the rear frame, the second measuring arm (7) of the rear frame, and the third measuring arm (8) of the rear frame respectively through the front optical path (2); the first measuring arm (3) of the front frame, the second measuring arm (4) of the front frame, and the third measuring arm (5) of the front frame are evenly distributed on the front frame (12) along the circumferential direction; the first measuring arm (6) of the rear frame, the second measuring arm (7) of the rear frame, and the third measuring arm (8) of the rear frame are evenly distributed on the rear frame (13) along the circumferential direction; The laser (1) is connected to a test board (9) via an optical fiber; the front frame first measuring arm (3), the front frame second measuring arm (4), the front frame third measuring arm (5), the rear frame first measuring arm (6), the rear frame second measuring arm (7), and the rear frame third measuring arm (8) are respectively connected to the test board (9) via optical fibers; and the test board (9) is connected to a data acquisition system (10) via a data line.

2. The space camera body size stability testing device according to claim 1, characterized in that: The front optical path (2) comprises a first beam splitter (2-1), a second beam splitter (2-2), a first folding mirror (2-3), a third beam splitter (2-4), a fourth beam splitter (2-5), a second folding mirror (2-6), a third folding mirror (2-7), a fifth beam splitter (2-8) and a fourth folding mirror (2-9); wherein: The second beam splitter (2-2) is arranged in the reflection direction of the first beam splitter (2-1), the first measuring arm (3) of the front frame is arranged in the reflection direction of the second beam splitter (2-2), the first folding mirror (2-3) is arranged in the transmission direction of the second beam splitter (2-2), the first measuring arm (6) of the rear frame is arranged in the reflection direction of the first folding mirror (2-3), the third beam splitter (2-4) is arranged in the transmission direction of the first beam splitter (2-1), the fourth beam splitter (2-5) is arranged in the reflection direction of the third beam splitter (2-4), and the second measuring arm (4) of the front frame is arranged in the reflection direction of the fourth beam splitter (2-5). The second folding mirror (2-6) is arranged in the transmission direction of the fourth beam splitter (2-5), the second measuring arm (7) of the rear frame is arranged in the reflection direction of the second folding mirror (2-6), the third folding mirror (2-7) is arranged in the transmission direction of the third beam splitter (2-4), the fifth beam splitter (2-8) is arranged in the reflection direction of the third folding mirror (2-7), the third measuring arm (5) of the front frame is arranged in the reflection direction of the fifth beam splitter (2-8), the fourth folding mirror (2-9) is arranged in the transmission direction of the fifth beam splitter (2-8), and the third measuring arm (8) of the rear frame is arranged in the reflection direction of the fourth folding mirror (2-9).

3. The space camera body size stability testing device according to claim 1 or 2, characterized in that: The first measuring arm (3) of the front frame comprises a first dual-frequency laser interferometer (3-1) and a first target mirror (3-2) of the front frame, the second measuring arm (4) of the front frame comprises a second dual-frequency laser interferometer (4-1) and a second target mirror (4-2) of the front frame, the third measuring arm (5) of the front frame comprises a third dual-frequency laser interferometer (5-1) and a third target mirror (5-2) of the front frame, the first measuring arm (6) of the rear frame comprises a fourth dual-frequency laser interferometer (6-1) and a first target mirror (6-2) of the rear frame, and the second measuring arm (7) of the rear frame comprises a The third measuring arm (8) of the rear frame includes a sixth dual-frequency laser interferometer (8-1) and a third target mirror (8-2) of the rear frame, and the first dual-frequency laser interferometer (3-1), the second dual-frequency laser interferometer (4-1), the third dual-frequency laser interferometer (5-1), the fourth dual-frequency laser interferometer (6-1), the fifth dual-frequency laser interferometer (7-1), and the sixth dual-frequency laser interferometer (8-1) are respectively connected to the test board (9) through optical fibers.

4. The space camera body size stability testing device according to claim 3, characterized in that: The first target mirror (3-2) of the front frame, the second target mirror (4-2) of the front frame and the third target mirror (5-2) of the front frame are evenly distributed on the front frame (12) along the circumferential direction, and the first target mirror (3-2) of the front frame, the second target mirror (4-2) of the front frame and the third target mirror (5-2) of the front frame form a plane; the first target mirror (6-2) of the rear frame, the second target mirror (7-2) of the rear frame and the third target mirror (8-2) of the rear frame are evenly distributed on the rear frame (13) along the circumferential direction, and the first target mirror (6-2) of the rear frame, the second target mirror (7-2) of the rear frame and the third target mirror (8-2) of the rear frame form a plane.

5. The space camera body size stability testing device according to claim 2, characterized in that: The first folding mirror (2-3), the second folding mirror (2-6), the third folding mirror (2-7), the fourth folding mirror (2-9), the first target mirror (3-2) of the front frame, the second target mirror (4-2) of the front frame, the third target mirror (5-2) of the front frame, the first target mirror (6-2) of the rear frame, the second target mirror (7-2) of the rear frame and the third target mirror (8-2) of the rear frame are all plane reflectors.

6. The space camera body size stability testing device according to claim 2, characterized in that: The light energy deviation ratio between any two measuring arms among the front frame first measuring arm (3), the front frame second measuring arm (4), the front frame third measuring arm (5), the rear frame first measuring arm (6), the rear frame second measuring arm (7) and the rear frame third measuring arm (8) is less than or equal to 5%.

7. The space camera body size stability testing device according to claim 1, characterized in that: The laser (1) is a dual-frequency HeNe laser.

8. A method for testing the dimensional stability of a space camera body, implemented by using the device for testing the dimensional stability of a space camera body according to any one of claims 1 to 7, characterized in that: The method comprises measuring the translation amount of the front frame (12), measuring the translation amount of the rear frame (13), measuring the inclination amount of the front frame (12), and measuring the inclination amount of the rear frame (13); wherein: The translation measurement of the front frame (12) includes: The laser light emitted by the laser (1) enters the first measuring arm (3) of the front frame, the second measuring arm (4) of the front frame and the third measuring arm (5) of the front frame respectively through the front optical path (2). The interference light signals generated by the first measuring arm (3) of the front frame, the second measuring arm (4) of the front frame and the third measuring arm (5) of the front frame are respectively transmitted to the test board (9), converted into digital signals and transmitted to the data acquisition system (10). After calculation, the displacement changes of the three measuring positions on the front frame (12) are obtained. , for the three displacement changes Calculate the translation of the front frame (12) : ； The translation measurement of the rear frame (13) includes: The laser light emitted by the laser (1) enters the first measuring arm (6), the second measuring arm (7) and the third measuring arm (8) of the rear frame through the front optical path (2). The interference light signals generated by the first measuring arm (6), the second measuring arm (7) and the third measuring arm (8) of the rear frame are respectively transmitted to the test board (9), converted into digital signals and transmitted to the data acquisition system (10). After calculation, the displacement changes of the three measuring positions on the rear frame (13) are obtained. , for the three displacement changes The translation of the rear frame (13) is calculated : ； The tilt measurement of the front frame (12) includes pitch angle measurement and yaw angle measurement. Assume that the distribution circle diameters of the first measuring arm (3) of the front frame, the second measuring arm (4) of the front frame and the third measuring arm (5) of the front frame are ,but: The pitch angle measurement of the front frame (12) includes: Distribution circle diameter and displacement change Calculate the pitch angle of the front frame (12) : ； The measurement of the torsion angle of the front frame (12) includes: Distribution circle diameter and displacement change The yaw angle of the front frame (12) is calculated : ； The tilt measurement of the rear frame (13) includes pitch angle measurement and yaw angle measurement. Assume that the distribution circle diameters of the first target mirror (6-2) of the rear frame, the second target mirror (7-2) of the rear frame, and the third target mirror (8-2) of the rear frame are ,but: The pitch angle measurement of the rear frame (13) includes: Distribution circle diameter and displacement change Calculate the pitch angle of the rear frame (13) : ； The measurement of the torsion angle of the rear frame (13) includes: Distribution circle diameter and displacement change The yaw angle of the front frame (12) is calculated : 。 9. The method for testing the dimensional stability of a space camera body according to claim 8, characterized in that: According to the translation of the front frame (12) and the translation of the rear frame (13) Calculate the translation of the front frame (12) relative to the rear frame (13) : ； According to the pitch angle of the front frame (12) and the pitch angle of the rear frame (13) Calculate the pitch angle of the front frame (12) relative to the rear frame (13) : ； According to the torsion angle of the front frame (12) and the yaw angle of the rear frame (13) Calculate the yaw angle of the front frame (12) relative to the rear frame (13) : 。 10. The method for testing the dimensional stability of a space camera body according to claim 8, characterized in that: The front optical path (2) comprises a first beam splitter (2-1), a second beam splitter (2-2), a first folding mirror (2-3), a third beam splitter (2-4), a fourth beam splitter (2-5), a second folding mirror (2-6), a third folding mirror (2-7), a fifth beam splitter (2-8) and a fourth folding mirror (2-9); The first measuring arm (3) of the front frame comprises a first dual-frequency laser interferometer (3-1) and a first target mirror (3-2) of the front frame, the second measuring arm (4) of the front frame comprises a second dual-frequency laser interferometer (4-1) and a second target mirror (4-2) of the front frame, the third measuring arm (5) of the front frame comprises a third dual-frequency laser interferometer (5-1) and a third target mirror (5-2) of the front frame, the first measuring arm (6) of the rear frame comprises a fourth dual-frequency laser interferometer (6-1) and a first target mirror (6-2) of the rear frame, the second measuring arm (7) of the rear frame comprises a fifth dual-frequency laser interferometer (7-1) and a second target mirror (7-2) of the rear frame, and the third measuring arm (8) of the rear frame comprises a sixth dual-frequency laser interferometer (8-1) and a third target mirror (8-2) of the rear frame; The laser light emitted by the laser (1) enters the first measuring arm (3) of the front frame after being reflected by the first beam splitter (2-1) and the second beam splitter (2-2), and is divided into reference light and test light by the first dual-frequency laser interferometer (3-1). The test light reaches the first target mirror (3-2) of the front frame and is reflected by the first target mirror (3-2) of the front frame and returns to the first dual-frequency laser interferometer (3-1), where it interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9) and converted into a digital signal, which is then transmitted to the data acquisition system (10) to acquire the displacement change of the first target mirror (3-2) of the front frame. ; The laser light emitted by the laser (1) enters the second measuring arm (4) of the front frame through transmission of the first beam splitter (2-1), reflection of the third beam splitter (2-4), and reflection of the fourth beam splitter (2-5), and is divided into reference light and test light by the second dual-frequency laser interferometer (4-1). After the test light reaches the second target mirror (4-2) of the front frame, it is reflected by the second target mirror (4-2) of the front frame and returns to the second dual-frequency laser interferometer (4-1), where it interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9), converted into a digital signal, and then transmitted to the data acquisition system (10), where the displacement change of the second target mirror (4-2) of the front frame is acquired. ; The laser light emitted by the laser (1) enters the third measuring arm (5) of the front frame after being transmitted by the first beam splitter (2-1), transmitted by the third beam splitter (2-4), reflected by the third folding mirror (2-7), and reflected by the fifth beam splitter (2-8), and is divided into reference light and test light by the third dual-frequency laser interferometer (5-1). The test light reaches the third target mirror (5-2) of the front frame and is reflected by the third target mirror (5-2) of the front frame and returns to the third dual-frequency laser interferometer (5-1), where it interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9), converted into a digital signal, and then transmitted to the data acquisition system (10), where the displacement change of the third target mirror (5-2) of the front frame is acquired. ; The laser light emitted by the laser (1) enters the first measuring arm (6) of the rear frame after being reflected by the first beam splitter (2-1), transmitted by the second beam splitter (2-2), and reflected by the first folding mirror (2-3), and is divided into reference light and test light by the fourth dual-frequency laser interferometer (6-1). The test light reaches the first target mirror (6-2) of the rear frame and is reflected by the first target mirror (6-2) of the rear frame and returns to the fourth dual-frequency laser interferometer (6-1), where it interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9), converted into a digital signal, and then transmitted to the data acquisition system (10), where the displacement change of the first target mirror (6-2) of the rear frame is acquired. ; The laser light emitted by the laser (1) is transmitted by the first beam splitter (2-1), reflected by the third beam splitter (2-4), transmitted by the fourth beam splitter (2-5), and reflected by the second folding mirror (2-6), and enters the second measuring arm (7) of the rear frame, and is divided into reference light and test light by the fifth dual-frequency laser interferometer (7-1). After the test light reaches the second target mirror (7-2) of the rear frame, it is reflected by the second target mirror (7-2) of the rear frame and returns to the fifth dual-frequency laser interferometer (7-1), and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9), converted into a digital signal, and then transmitted to the data acquisition system (10), and the displacement change amount of the second target mirror (7-2) of the rear frame is acquired. ; The laser light emitted by the laser (1) enters the third measuring arm (8) of the rear frame after being transmitted by the first beam splitter (2-1), transmitted by the third beam splitter (2-4), reflected by the third folding mirror (2-7), transmitted by the fifth beam splitter (2-8), and reflected by the fourth folding mirror (2-9), and is divided into reference light and test light by the sixth dual-frequency laser interferometer (8-1). After the test light reaches the third target mirror (8-2) of the rear frame, it is reflected by the third target mirror (8-2) of the rear frame and returns to the sixth dual-frequency laser interferometer (8-1), and interferes with the reference light to form an interference light signal. The interference light signal is transmitted to the test board (9), converted into a digital signal, and then transmitted to the data acquisition system (10), and the displacement change amount of the third target mirror (8-2) of the rear frame is acquired. .

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