Method for fast adjustment of a detection optical path of a space mirror based on laser tracking measurement

Abstract

The application relates to a laser tracking measurement-based space mirror detection light path rapid adjustment method, which comprises the following steps: constructing a coordinate system of a compensator, determining first initial coordinate parameters of a tracking instrument target ball fixed point position of a random position of a surface of the compensator; constructing a coordinate system of a to-be-detected aspheric mirror, determining second initial coordinate parameters of a tracking instrument target ball fixed point position of a random position of an outer cylindrical surface of the to-be-detected aspheric mirror; building a surface shape detection light path: selecting a detection tower according to the length of a to-be-detected mirror surface shape detection light path, fixing the detection tower on an air floating shock isolation platform, opening the detection tower, and sequentially placing an interferometer, the compensator and a folding mirror on the top surface of the detection tower. The application realizes rapid convergence of a mirror detection light path misadjustment amount, improves mirror surface shape detection efficiency, and improves the accuracy of test data.

Description

Technical Field

[0001] This invention relates to a method for rapid adjustment of the detection optical path of a space reflector based on laser tracking measurement, belonging to the overall technical field of missile systems. Background Technology

[0002] As commercial high-density remote sensing constellations gradually become a mainstream technology in the field of space remote sensing, higher demands are being placed on the manufacturing efficiency of remote sensing cameras. The current meticulous R&D and prototyping model can no longer meet production capacity requirements. As a frequently performed inspection step in the manufacturing process of remote sensing cameras, the efficiency of mirror surface shape inspection directly affects the camera's development cycle.

[0003] Currently, both domestically and internationally, the inspection process for reflective mirror surfaces relies on manual observation and judgment, depending on human experience for optical path adjustment. This results in poor adjustment accuracy and low adjustment efficiency. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a method for rapid adjustment of the optical path of a space reflector based on laser tracking measurement, so as to achieve rapid convergence of the optical path misalignment of the reflector detection, thereby improving the efficiency of reflector surface shape detection and the accuracy of test data.

[0005] The solution of the present invention is:

[0006] A method for rapid adjustment of the optical path of a space reflector based on laser tracking measurement includes: constructing the coordinate system of the compensator and determining the first initial coordinate parameters of the fixed point of the tracker target ball determined by the random position on the surface of the compensator;

[0007] Construct a coordinate system for the aspherical mirror under test, and determine the second initial coordinate parameters for the fixed point of the target ball of the tracker by determining the random position of the outer cylindrical surface of the aspherical mirror under test.

[0008] Constructing the surface shape detection optical path: Select the detection tower according to the length of the surface shape detection optical path of the mirror under test, fix the detection tower on the air-floating vibration isolation platform, make an opening in the detection tower, and place the interferometer, compensator, and folding mirror in sequence on the top surface of the detection tower, with the folding mirror located at the center of the opening. Place the first adjustment platform and the second adjustment platform at the bottom of the interferometer and the compensator, respectively; set the third adjustment platform at the bottom of the aspherical mirror under test, and place the third adjustment platform and the aspherical mirror under test inside the detection tower, on the air-floating vibration isolation platform, located directly below the center of the opening of the detection tower;

[0009] Adjusting the surface shape detection optical path: A laser tracker is used to measure at least four points evenly distributed on the surface of the folding mirror, obtaining a mirror point set. The mirror plane is fitted based on this point set, and its angle with the horizontal ground plane is determined. Based on this angle, the tilt angle of the folding mirror is adjusted so that the angle between the mirror and the horizontal ground plane is 45° ± 0.01°. The laser tracker is used to measure the fixed point of the tracker target ball on the aspherical mirror under test, obtaining the second current coordinate parameters of the fixed point. Combined with the first initial coordinate parameters of the fixed point, the coordinate system XOY of the aspherical mirror under test is reconstructed. Based on the angle between the reconstructed XOY plane and the horizontal ground plane, the tilt angle of the aspherical mirror under test is adjusted using a third adjustment platform so that the reconstructed XOY plane is horizontal to the ground. The laser tracker is then used... The first current coordinate parameters of the fixed point of the tracker target ball on the compensator are obtained by measuring the target ball on the compensator. The coordinate system of the compensator is reconstructed by combining the first initial coordinate parameters. According to the deviation between the position of the compensator coordinate system and the theoretical position, the tilt and translation of the compensator are adjusted by the second adjustment platform so that the compensator is in the theoretical position. The tilt angle of the interferometer is adjusted by the first adjustment platform so that the outgoing light rays of the interferometer are horizontal with the ground. The tracker target ball is placed at the convergence point of the outgoing light rays of the interferometer, with the spherical surface facing the interferometer. The position of the tracker target ball is adjusted so that its center point coincides with the convergence point of the outgoing light rays of the interferometer. The interferometer fringes are obtained. The position of the tracker target ball at this time is measured by the laser tracker to obtain the position of the convergence point of the outgoing light rays of the interferometer. The interferometer is then translated so that the position of the convergence point of the outgoing light rays of the interferometer is the theoretical position. The optical path adjustment for the spatial reflecting mirror surface shape detection is completed.

[0010] Furthermore, the method for constructing the coordinate system of the compensator is as follows: Fixed points of the tracker target ball are randomly located on the surface of the compensator and numbered, with no fewer than four fixed points; a laser tracker is used to measure points evenly distributed on the outer cylindrical surface of the compensator, with no fewer than 20 measurement points, resulting in an outer cylindrical point set; a laser tracker is used to measure points evenly distributed on the end face of the compensator, with no fewer than 12 measurement points, resulting in an end face point set; the cylinder is fitted based on the outer cylindrical point set, and the central axis of the cylinder is obtained; the end plane is fitted based on the end face point set; the central axis of the cylinder is used as the Z-axis of the coordinate system, and the intersection of the Z-axis and the end plane is used as the origin of the coordinate system. Any point is selected in the plane passing through the origin and perpendicular to the Z-axis and determined as a point on the X-axis, thus establishing the compensator coordinate system.

[0011] Furthermore, the method for constructing the coordinate system of the aspherical mirror under test is as follows: Fixed points of the target ball for the tracker are randomly determined at random locations on the outer cylindrical surface of the aspherical mirror under test and numbered, with no fewer than 4 fixed points; the laser tracker is used to measure the uniformly distributed points on the outer cylindrical surface of the aspherical mirror under test, with no fewer than 20 measurement points, obtaining the outer cylindrical point set; the laser tracker is used to measure the uniformly distributed points on the end face of the aspherical mirror under test, with no fewer than 12 measurement points, obtaining the end face point set; the cylinder is fitted based on the outer cylindrical point set, and the central axis of the cylinder is obtained; the end plane is fitted based on the end face point set; the end plane is used as the XOY plane of the coordinate system, and the intersection of the central axis of the cylinder and the end plane is used as the origin of the coordinate system. Any point is selected in the XOY plane and determined as a point on the X-axis, thus establishing the coordinate system of the aspherical mirror under test.

[0012] Furthermore, the height of the detection tower is equal to the length of the optical path for detecting the surface shape of the mirror under test.

[0013] Furthermore, when the center point of the tracker target sphere coincides with the convergence point of the interferometer's emitted rays, the obtained interferometer fringes are flat, equally spaced fringes.

[0014] Furthermore, it also includes obtaining surface shape parameters: start the air-bearing vibration isolation platform, and after the air-bearing stabilizes, use interferometer 1 to measure the surface shape aberration coefficient of the aspherical mirror under test. According to the surface shape aberration parameters, adjust the positions of the interferometer and compensator until the surface shape aberration coefficient converges to 0.01, and obtain the final surface shape parameters of the aspherical mirror under test.

[0015] Furthermore, the third adjustment platform is a four-dimensional adjustment platform, capable of achieving two-dimensional tilt and two-dimensional translation adjustments.

[0016] Furthermore, the compensator includes a lens barrel and 2 to 3 transmission lenses placed in the lens barrel, with the optical axis of the lenses being coaxial with the central axis of the lens barrel structure.

[0017] Furthermore, the interferometer emits a standard spherical wave, which is adjusted by the compensator to become an aspherical wave. The aspherical wave is refracted 90° by the plane mirror and illuminated by the aspherical mirror under test. After reflection, it returns along the original path and interferes to form an image within the interferometer, thus obtaining the deviation between the actual shape and the theoretical shape of the mirror surface, i.e., the mirror surface shape error.

[0018] Furthermore, when adjusting the tilt and translation of the compensator via the second adjustment platform, the position adjustment deviation is less than 0.05mm and the angle adjustment deviation is less than 0.01°.

[0019] The advantages of this invention compared to the prior art are:

[0020] This invention achieves quantitative automatic adjustment of the detection optical path through laser tracking measurement, which greatly improves the efficiency of surface shape detection and effectively eliminates the interference of operators on the testing environment. It is also highly applicable to special environments and products such as low temperature, vacuum environment and non-visible spectrum. Attached Figure Description

[0021] Figure 1 This is an aspherical mirror surface shape detection system.

[0022] Figure 2 The collimated interference fringes of the target ball of the tracker when it is at the focal position of the interferometer;

[0023] Figure 3 For the compensator structural configuration;

[0024] Figure 4 This is a schematic diagram of an aspherical reflecting mirror structure. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments.

[0026] A method for rapid adjustment of the optical path for detecting space mirrors based on laser tracking measurement includes:

[0027] Construct the coordinate system of compensator 2 and determine the first initial coordinate parameters of the fixed point of the tracker target ball determined by the random position on the surface of compensator 2;

[0028] Construct a coordinate system for the aspherical mirror 4 to be tested, and determine the second initial coordinate parameters for the fixed point of the target ball of the tracker by determining the random position of the outer cylindrical surface of the aspherical mirror 4 to be tested.

[0029] Setting up the surface shape detection optical path: Select detection tower 6 according to the length of the surface shape detection optical path of the mirror to be tested, such as... Figure 1 As shown, the testing tower is fixed on the air-floating vibration isolation platform 7. An opening is made in the testing tower. The interferometer 1, compensator 2, and folding mirror 3 are placed sequentially on the top surface of the testing tower. The folding mirror 3 is located at the center of the opening, with a positional deviation of no more than 2mm. The first adjustment platform 8 and the second adjustment platform 9 are placed at the bottom of the interferometer 1 and the compensator 2, respectively. The bottom of the aspherical reflector 4 to be tested is set with a third adjustment platform 10. The third adjustment platform, together with the aspherical reflector 4 to be tested, is placed inside the testing tower and on the air-floating vibration isolation platform, located directly below the center of the opening of the testing tower.

[0030] Adjusting the surface shape detection optical path: Using a laser tracker, measure at least four points evenly distributed on the surface of the folding mirror 3 to obtain a mirror point set; fit the mirror plane based on the mirror point set and determine its angle with the horizontal plane of the earth; adjust the tilt angle of the folding mirror 3 according to this angle so that the angle between the mirror and the horizontal plane of the earth is 45°±0.01°; use a laser tracker to measure the fixed point of the tracker target ball on the aspherical reflector 4 to obtain the second current coordinate parameters of the fixed point. Based on the initial coordinate parameters of the fixed point, the XOY coordinate system of the aspherical reflector under test is reconstructed. According to the angle between the reconstructed XOY plane and the horizontal plane of the earth, the tilt angle of the aspherical reflector 4 is adjusted using the third adjustment platform to make the reconstructed XOY plane horizontal with the earth, with an angle adjustment deviation of less than ±0.01°. The target ball of the tracker on the compensator 2 is measured using a laser tracker to obtain the first initial coordinate parameters of the fixed point. The compensator coordinate system is reconstructed using the first initial coordinate parameters. Based on the deviation between the compensator coordinate system position and the theoretical position, the tilt and translation of the compensator 2 are adjusted using the second adjustment platform to ensure that the compensator is in the theoretical position, with a position adjustment deviation of less than 0.05 mm and an angle adjustment deviation of less than ±0.01°. The tilt angle of the interferometer 1 is adjusted using the first adjustment platform to make the interferometer's emitted light horizontal with the ground, with an angle adjustment deviation of less than ±0.01°. The tracker target ball 5 is placed at the convergence point of the interferometer 1's emitted light, with the spherical surface facing the interferometer 1. The position of the tracker target ball 5 is adjusted so that its center point coincides with the convergence point of the interferometer 1's emitted light, and the interferometer fringes are obtained. The position of the tracker target ball 5 at this time is measured using a laser tracker to obtain the convergence point position of the interferometer 1's emitted light. The interferometer 1 is then translated so that the convergence point position of the interferometer 1's emitted light is the theoretical position, with a position adjustment deviation of less than 0.05 mm. This completes the rapid adjustment of the optical path for the space reflector detection.

[0031] The method for constructing the coordinate system of compensator 2 is as follows: Figure 3 As shown, at random locations on the surface of compensator 2, the target ball of the tracker is fixed at fixed points 14 and numbered, with no fewer than 4 fixed points; the laser tracker is used to measure the points 15 evenly distributed on the outer cylindrical surface of compensator 2, with no fewer than 20 measurement points, to obtain the outer cylindrical point set; the laser tracker is used to measure the points evenly distributed on the end face 16 of compensator, with no fewer than 12 measurement points, to obtain the end face point set; the cylinder is fitted based on the outer cylindrical point set and the central axis of the cylinder is obtained; the end plane is fitted based on the end face point set; the central axis of the cylinder is used as the Z-axis of the coordinate system, and the intersection of the Z-axis and the end plane is used as the origin of the coordinate system. Any point is taken in the plane passing through the origin and perpendicular to the Z-axis and determined as a point on the X-axis, thus establishing the coordinate system of compensator 2.

[0032] The method for constructing the coordinate system of the aspherical mirror 4 to be tested is as follows: Figure 4 As shown, at random positions on the outer cylindrical surface of the aspherical mirror 4 under test, the target ball of the tracker is fixed at point 11 and numbered, with no less than 4 fixed points; the laser tracker is used to measure the points 12 uniformly distributed on the outer cylindrical surface of the aspherical mirror 4 under test, with no less than 20 measurement points, to obtain the outer cylindrical point set; the laser tracker is used to measure the points 12 uniformly distributed on the end face 13 of the aspherical mirror under test, with no less than 12 measurement points, to obtain the end face point set; the cylinder is fitted based on the outer cylindrical point set and the central axis of the cylinder is obtained; the end plane is fitted based on the end face point set; the end plane is used as the XOY plane of the coordinate system, and the intersection of the central axis of the cylinder and the end plane is used as the origin of the coordinate system. Any point is taken in the XOY plane and determined as a point on the X-axis to establish the coordinate system of the aspherical mirror 4 under test.

[0033] The height of the detection tower is equal to the length of the detection optical path for the surface shape of the mirror to be tested.

[0034] When the center point of the target ball 5 of the tracker coincides with the convergence point of the rays emitted from the interferometer 1, the acquired interferometer fringes are flat, equally spaced fringes, such as... Figure 2 As shown.

[0035] It also includes obtaining surface shape parameters: start the air-float vibration isolation platform, and after the air float stabilizes, use interferometer 1 to measure the surface shape aberration coefficient of the aspherical mirror 4 under test. According to the surface shape aberration parameters, adjust the positions of interferometer 1 and compensator 2 until the surface shape aberration coefficient converges to 0.01, and obtain the final surface shape parameters of the aspherical mirror 4 under test.

[0036] The third adjustment platform is a four-dimensional adjustment platform, capable of adjusting two-dimensional tilt and two-dimensional translation.

[0037] The compensator 2 includes a lens barrel and 2 to 3 transmission lenses placed in the lens barrel, with the optical axis of the lens being coaxial with the central axis of the lens barrel structure.

[0038] Interferometer 1 emits a standard spherical wave, which is adjusted by compensator 2 to become an aspherical wave. The aspherical wave is refracted by plane mirror 3 and rotated 90° to illuminate the surface of the aspherical mirror 4 under test. After reflection, it returns along the original path and interferes to form an image in interferometer 1. The deviation between the actual shape and the theoretical shape of the mirror surface is obtained, which is the mirror surface shape error.

[0039] This invention primarily addresses the surface shape detection process of space aspherical mirrors, meeting the rapid surface shape detection requirements in the mass production of high-performance remote sensing cameras. A laser tracker combined with a space multi-dimensional precision adjustment stage is used to rapidly position and adjust the aspherical mirror, folding mirror, compensator, and laser interferometer in the optical path for surface shape detection, quickly converging the misalignment deviation of the test optical path within the interferometer's detection range. Then, based on the aberration coefficients measured by the interferometer, a precision adjustment mechanism is used to finally determine the surface shape parameters of the mirror.

[0040] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for rapid adjustment of the optical path for detecting a space mirror based on laser tracking measurement, characterized in that, include: Construct the coordinate system of the compensator (2) and determine the first initial coordinate parameters of the fixed point of the tracker target ball determined by the random position on the surface of the compensator (2); Construct a coordinate system for the aspherical mirror (4) to be tested, and determine the second initial coordinate parameters of the target ball fixed position of the tracker by determining the random position of the outer cylindrical surface of the aspherical mirror (4); Set up the surface shape detection optical path: Select the detection tower according to the length of the surface shape detection optical path of the mirror to be tested, fix the detection tower on the air-floating vibration isolation platform, make an opening on the detection tower, and place the interferometer (1), compensator (2), and folding mirror (3) on the top surface of the detection tower in sequence. The folding mirror (3) is located at the center of the opening. The first adjustment platform and the second adjustment platform are placed at the bottom of the interferometer (1) and the compensator (2) respectively. The third adjustment platform is set at the bottom of the aspherical mirror (4) to be tested. The third adjustment platform and the aspherical mirror (4) to be tested are placed inside the detection tower and on the air-floating vibration isolation platform, located directly below the center of the opening of the detection tower. Adjusting the surface shape detection optical path: Using a laser tracker, measure the points evenly distributed on the mirror surface of the folding mirror (3), with no less than 4 points measured, to obtain a mirror point set; fit the mirror plane according to the mirror point set and determine its angle with the horizontal plane of the earth; based on this angle, adjust the tilt angle of the mirror surface of the folding mirror (3) so that the angle between the mirror surface and the horizontal plane of the earth is 45°±0.01°; use a laser tracker to measure the fixed point of the tracker target ball on the aspherical mirror (4) to obtain the second current coordinate parameter of the fixed point; combine the first initial coordinate parameter of the fixed point to reconstruct the coordinate system XOY of the aspherical mirror to be tested; based on the angle between the reconstructed XOY plane of the aspherical mirror to be tested and the horizontal plane of the earth, adjust the tilt angle of the aspherical mirror (4) through the third adjustment platform so that the reconstructed XOY plane of the aspherical mirror to be tested is horizontal with the earth; use a laser tracker to measure the tracking on the compensator (2). The target ball is fixed at a fixed point, and the first current coordinate parameters of the fixed point are obtained. The coordinate system of the compensator is reconstructed by combining the first initial coordinate parameters. According to the deviation between the position of the compensator coordinate system and the theoretical position, the tilt and translation of the compensator (2) are adjusted by the second adjustment platform so that the compensator is in the theoretical position. The tilt angle of the interferometer (1) is adjusted by the first adjustment platform so that the outgoing light of the interferometer is horizontal with the ground. The target ball (5) of the tracker is placed at the convergence point of the outgoing light of the interferometer (1), and the spherical surface is facing the interferometer (1). The position of the target ball (5) of the tracker is adjusted so that its center point coincides with the convergence point of the outgoing light of the interferometer (1). The interferometer fringes are obtained. The position of the target ball (5) of the tracker is measured by the laser tracker at this time to obtain the position of the convergence point of the outgoing light of the interferometer (1). The interferometer (1) is translated so that the position of the convergence point of the outgoing light of the interferometer (1) is the theoretical position. The optical path adjustment for the detection of the surface shape of the space reflecting mirror is completed.

2. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The method for constructing the coordinate system of the compensator (2) is as follows: the fixed points of the target ball of the tracker are determined at random positions on the surface of the compensator (2) and numbered, with no less than 4 fixed points; the points uniformly distributed on the outer cylinder surface of the compensator (2) are measured using a laser tracker, with no less than 20 points measured, to obtain the outer cylinder point set; the points uniformly distributed on the end face of the compensator (2) are measured using a laser tracker, with no less than 12 points measured, to obtain the end face point set; the cylinder is fitted based on the outer cylinder point set and the cylinder central axis is obtained; the end plane is fitted based on the end face point set; the cylinder central axis is taken as the Z-axis of the coordinate system, and the intersection of the Z-axis and the end plane is taken as the origin of the coordinate system. Any point is taken in the plane passing through the origin and perpendicular to the Z-axis and determined as a point on the X-axis to establish the coordinate system of the compensator (2).

3. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The method for constructing the coordinate system of the aspherical mirror (4) to be tested is as follows: the target ball of the tracker is randomly located on the outer cylindrical surface of the aspherical mirror (4) to be tested and the fixed points are numbered. The number of fixed points is not less than 4. The laser tracker is used to measure the points evenly distributed on the outer cylindrical surface of the aspherical mirror (4) to be tested. The number of measurement points is not less than 20, and the outer cylindrical point set is obtained. The laser tracker is used to measure the points evenly distributed on the end face of the aspherical mirror (4) to be tested. The number of measurement points is not less than 12, and the end face point set is obtained. The cylinder is fitted based on the outer cylindrical point set and the central axis of the cylinder is obtained. The end plane is fitted based on the end face point set. The end plane is used as the XOY plane of the coordinate system. The intersection of the central axis of the cylinder and the end plane is used as the origin of the coordinate system. Any point is taken in the XOY plane and determined as a point on the X-axis. The coordinate system of the aspherical mirror (4) to be tested is established.

4. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The height of the detection tower is equal to the length of the detection optical path for the surface shape of the mirror to be tested.

5. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, When the center point of the target ball (5) of the tracker coincides with the convergence point of the emitted light from the interferometer (1), the obtained interferometer fringes are flat and equally spaced fringes.

6. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, After completing the optical path adjustment for the surface shape detection of the space reflector, the method also includes obtaining surface shape parameters: start the air-floating vibration isolation platform, and after the air-floating is stable, use the interferometer (1) to measure the surface shape aberration coefficient of the aspherical reflector (4) to be tested. According to the surface shape aberration parameters, adjust the positions of the interferometer (1) and the compensator (2) until the surface shape aberration coefficient converges to 0.01, and obtain the final surface shape parameters of the aspherical reflector (4) to be tested.

7. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The third adjustment platform is a four-dimensional adjustment platform, capable of adjusting two-dimensional tilt and two-dimensional translation.

8. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The compensator (2) includes a lens barrel and 2 to 3 transmission lenses placed in the lens barrel. The optical axis of the lens is coaxial with the central axis of the lens barrel structure.

9. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, The interferometer (1) emits a standard spherical wave, which is adjusted to an aspherical wave by the compensator (2). The aspherical wave is refracted by the plane mirror (3) and irradiated by 90° to the surface of the aspherical mirror (4) to be tested. After reflection, it returns along the original path and is imaged in the interferometer (1). The deviation between the actual shape and the theoretical shape of the mirror surface is obtained, that is, the mirror surface shape error.

10. The method for rapid adjustment of the optical path for space mirror detection based on laser tracking measurement according to claim 1, characterized in that, When the compensator (2) is tilted and translated by adjusting the second adjustment platform, the position adjustment deviation is less than 0.05mm and the angle adjustment deviation is less than 0.01°.

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