Coaxial reflective optical system and adjustment method
By using threaded knobs to replace air interval adjustment in coaxial reflective optical systems, combined with laser interference wave aberration method and bonding and curing technology, the problem of high assembly accuracy requirements is solved, and efficient assembly and adjustment of the optical system is achieved.
Patent Information
- Application Number
- CN202411594813.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-10
- Publication Date
- 2024-12-31
AI Technical Summary
During the assembly process, the existing coaxial reflective optical system has high accuracy requirements for the air separation adjustment washer, which leads to multiple grinding and re-inspections, and has a long assembly cycle.
The air interval adjustment washer is replaced by the threaded knob, and the threaded connection of the secondary mirror support is achieved instant and precise adjustment, eliminating washer measurement and processing processes, and the assembly reference is established and bonded and cured by laser interference wave aberration method.
It greatly improves the assembly efficiency of the optical system, simplifies the assembly process, reduces the grinding and re-inspection steps, and shortens the assembly cycle.
Smart Images
Figure CN119224966A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of precision optical-mechanical assembly and adjustment of an airborne optoelectronic aiming system, and in particular to a coaxial reflective optical system and an assembly and adjustment method. Background Art
[0002] In recent years, with the development of airborne weapons, higher and higher requirements have been put forward for airborne optoelectronic detection equipment, and airborne optoelectronic products have been continuously developing towards high sensitivity, high resolution, and long-distance detection. Airborne optical systems mostly use reflective optical systems with large aperture, long detection distance, long focal length, high resolution, and no chromatic aberration. This system has a compact structure and can effectively shorten the length of the optical tube. It is currently a hot research topic in the field of airborne aviation at home and abroad.
[0003] At present, the most widely used is the Cassegrain optical system or the coaxial reflective optical system derived and optimized based on it. This type of system is generally composed of a primary mirror, a primary mirror mount, an adjustment gasket, a secondary mirror support, and a secondary mirror. The structural diagram is shown in the figure. Figure 8 As shown. The primary and secondary mirrors are assembled into their respective mirror seats, and the two are connected by adjusting washers. The adjusting washers can be ground to ensure that the air gap value between the primary and secondary mirrors meets the index requirements. The system usually uses the laser interference wave aberration method for adjustment. This method can be measured and adjusted, and the evaluation is objective. It is a more mainstream reflective system adjustment method. The thickness value of the adjustment washer is determined by the interferometer test results, and then the washer is disassembled for grinding.
[0004] However, this type of structure requires gasket thickness measurement and grinding processes. At the same time, since the gasket thickness value is very sensitive to the spherical aberration value of the optical system aberration item, the grinding processing accuracy is required to be high. It may occur that the parts are ground multiple times and the wavefront is re-inspected, which ultimately leads to cumbersome assembly processes and long assembly cycles for this system.
[0005] Therefore, it is necessary to provide a coaxial reflective optical system and an adjustment method to solve the above problems. Summary of the invention
[0006] The present invention provides a coaxial reflective optical system and an assembly and adjustment method. The original structural form is optimized and improved, an air gap adjustment gasket is removed, and a secondary mirror support is optimized and changed into a threaded knob form, so as to ensure instant and precise adjustment of the air gap and complete the system assembly at one time. Since the measurement and processing of the gasket and the system re-inspection processes are omitted, the assembly and adjustment efficiency of the optical system is greatly improved, so as to solve the existing problems that the requirements for the processing accuracy of grinding are high, multiple grinding of parts and wavefront re-inspection may occur, which ultimately leads to complicated assembly processes and long assembly cycles of the optical system.
[0007] A coaxial reflective optical system and an adjustment method of the present invention adopt the following technical solutions, including: It includes a primary mirror assembly and a secondary mirror assembly connected to the mirror seat of the primary mirror assembly, wherein the secondary mirror assembly includes: a secondary mirror bracket and a threaded pressing ring, the middle part of the secondary mirror bracket is threadedly connected to the secondary mirror seat, and the secondary mirror is installed in the secondary mirror seat; the threaded pressing ring is used to press the secondary mirror seat.
[0008] Preferably, the secondary mirror bracket includes: an annular frame and a connecting ring arranged concentrically with the annular frame, the connecting ring and the annular frame are connected by ribs, wherein the connecting ring is connected to the secondary mirror seat and the threaded pressure ring by threads, and the annular frame is provided with a plurality of mounting holes for connecting to the primary mirror seat of the primary mirror assembly.
[0009] Preferably, a clamping groove is provided on the threaded pressing ring, and the clamping groove is used for clamping with the pressing ring wrench.
[0010] Preferably, a fastening screw is provided on the secondary mirror seat, and the fastening screw is passed through the secondary mirror seat to tighten the secondary mirror.
[0011] A method for assembling and adjusting a coaxial reflective optical system, comprising: Centering and assembling the primary mirror assembly; Laser interference wave aberration method is used to assemble and adjust the primary mirror assembly to establish the assembly benchmark of the optical system; Assemble and adjust the secondary mirror assembly according to the assembly datum of the optical system; Bonding and curing the primary mirror assembly and the secondary mirror assembly of the optical system, and bonding and curing the secondary mirror assembly; A stress release experiment is conducted, and after the test, the wavefront of the optical system is re-checked. After the re-check meets the total wavefront RMS index, the final assembly and adjustment of the optical system is completed.
[0012] Preferably, the steps of centering and assembling the primary mirror assembly are: Place the primary mirror of the primary mirror assembly in the primary mirror holder and fix it on the air-floating turntable; Observe the circle drawing amount of the fitting spherical center image of the primary mirror through the centering instrument, detect the end jump value of the primary mirror using the chromatic aberration displacement sensor, and adjust the adjustment screws on the primary mirror mount so that the circle drawing amount of the fitting spherical center image of the primary mirror and the end jump value meet the centering requirements; Remove the adjusting screw and perform glue injection and curing.
[0013] Preferably, the steps of assembling and adjusting the primary mirror assembly using the laser interference wave aberration method to establish the assembly reference of the optical system are: Place the large-aperture laser interferometer horizontally; A three-dimensional translation adjustment table and a two-dimensional angle adjustment table are sequentially placed in the working area of the large-aperture laser interferometer; A standard ball is set on the three-dimensional translation adjustment table, and a primary mirror assembly is set on the two-dimensional angle adjustment table; The two-dimensional angle adjustment stage is roughly adjusted to make the primary mirror assembly enter the light envelope aperture of the large-aperture laser interferometer; Adjust the three-dimensional translation adjustment stage so that the center of the standard sphere coincides with the focus of the primary mirror assembly; Fine-tune the position of the standard sphere, and fine-tune the azimuth and pitch angles of the two-dimensional angle adjustment stage to make the coma term of the wavefront Zernike coefficient of the primary mirror assembly less than 0.02mm. At this time, the position of the primary mirror assembly is the assembly reference of the entire optical system.
[0014] Preferably, the steps of adjusting the secondary mirror assembly according to the assembly reference of the optical system are: The secondary mirror assembly is placed between the primary mirror assembly and the large-aperture laser interferometer after the assembly reference is established; Connecting the annular frame of the secondary mirror assembly to the primary mirror mount of the primary mirror assembly; The three-dimensional translation adjustment stage and the standard ball thereon are placed at a primary imaging point on the side of the primary mirror assembly away from the secondary mirror assembly, and the center of the standard ball coincides with the focal position after reflection from the secondary mirror assembly; Fine-tune the position of the standard sphere, and fine-tune the translation and tilt of the secondary mirror in the secondary mirror assembly. Adjust the air gap between the primary and secondary mirrors by twisting the secondary mirror mount until the wavefront Zernike coefficient astigmatism, coma, and spherical aberration of the optical system are less than 0.02mm, completing the adjustment of the optical system.
[0015] Preferably, the step of bonding and curing the primary mirror assembly and the secondary mirror assembly of the optical system is: after the optical system is assembled and adjusted, epoxy resin glue is applied between the connecting ring of the secondary mirror bracket and the secondary mirror seat for bonding and curing.
[0016] Preferably, the steps of bonding and curing the secondary mirror assembly are: fastening the secondary mirror seat with a threaded pressure ring, coating the threads of the threaded pressure ring with a thread locking agent; removing the fastening screws on the secondary mirror seat, and injecting silicone rubber into the screw holes for curing.
[0017] The beneficial effects of the present invention are: The secondary mirror support of the secondary mirror assembly is divided into two parts to form a secondary mirror seat and a secondary mirror bracket, and the secondary mirror seat and the secondary mirror bracket are connected by threads, thereby eliminating the traditional air gap adjustment gasket method and replacing it with a threaded knob to adjust the air gap, thereby ensuring instant and precise adjustment of the air gap and completing the system assembly in one go. Since the measurement, processing and system re-inspection processes of the adjustment gasket are omitted, the optical system assembly efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0019] Figure 1 It is a structural schematic diagram of a secondary mirror assembly of a coaxial reflective optical system of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure of the secondary mirror support in FIG. Figure 3 for Figure 1 Schematic diagram of the structure of the secondary mirror mount; Figure 4 for Figure 1 A schematic diagram of the structure of the threaded pressing ring; Figure 5 A schematic diagram of centering and assembling the primary mirror assembly in an embodiment of the present invention; Figure 6 A schematic diagram of assembling and adjusting the primary mirror assembly to establish an assembly reference for the optical system in an embodiment of the present invention; Figure 7 is a schematic diagram of assembling and adjusting the secondary mirror assembly in an embodiment of the present invention; Figure 8 This is a schematic diagram of the existing coaxial reflection system.
[0020] In the figure: 1. primary mirror; 2. primary mirror mount; 3. annular frame; 4. connecting ring; 5. secondary mirror; 6. secondary mirror mount; 7. secondary mirror bracket; 8. threaded pressure ring; 9. adjustment screw; 10. air-floating turntable; 11. centering device; 12. chromatic aberration displacement sensor; 13. large-aperture laser interferometer; 14. standard ball; 15. three-dimensional translation adjustment stage; 16. two-dimensional angle adjustment stage; 17. secondary mirror assembly. DETAILED DESCRIPTION
[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0022] An embodiment of a coaxial reflective optical system of the present invention is as follows Figure 1As shown, it includes: a main mirror assembly and a secondary mirror assembly 17 connected to the mirror seat of the main mirror assembly, wherein the secondary mirror assembly 17 includes: a secondary mirror bracket 7 and a threaded pressing ring 8, the middle part of the secondary mirror bracket 7 is threadedly connected to the secondary mirror seat 6, and the secondary mirror 5 is installed in the secondary mirror seat 6; the threaded pressing ring 8 is used to press the secondary mirror seat 6.
[0023] Specifically, the secondary mirror bracket 7 includes: an annular frame 3 and a connecting ring 4 concentrically arranged with the annular frame 3, wherein the connecting ring 4 and the annular frame 3 are connected via ribs, wherein the connecting ring 4 is connected to the secondary mirror seat 6 and the threaded pressure ring 8 via threads, and the annular frame 3 is provided with a plurality of mounting holes for connecting with the primary mirror seat 2 of the primary mirror assembly.
[0024] Specifically, a clamping groove is provided on the threaded pressing ring 8, and the clamping groove is used for clamping with the pressing ring wrench.
[0025] Specifically, a fastening screw is provided on the secondary mirror seat 6 , and the fastening screw is passed through the secondary mirror seat 6 to tighten the secondary mirror 5 .
[0026] It should be noted that if Figure 1 As shown, in the present invention, the existing secondary mirror support is divided into two parts, namely, a secondary mirror bracket 7 and a secondary mirror seat 6. The secondary mirror bracket 7 removes the mounting flange of the existing secondary mirror, as shown in FIG. Figure 2 As shown, the secondary mirror 5 on the secondary mirror bracket 7 is installed in the connecting ring 4, and the interior of the connecting ring 4 is a through hole, the through hole has an increased diameter and is processed with precision threads; Figure 3 As shown, the secondary mirror seat 6 retains the original screw holes evenly distributed around the secondary mirror, which is convenient for fine-tuning the secondary mirror 5 and subsequent glue injection and curing. The outer periphery and the inner hole of the connecting ring 4 of the secondary mirror bracket 7 are equipped with precision threads to ensure that the secondary mirror seat 6 can be screwed back and forth in the connecting ring 4 of the secondary mirror bracket 7. At the same time, the outer diameter of the mirror seat where the screw holes are arranged on the secondary mirror seat 6 is larger than the outer diameter where the threads are arranged. This design will ensure that the screw holes of the secondary mirror seat 6 will not be screwed into the inner hole of the connecting ring 4 of the secondary mirror bracket 7. Since the secondary mirror seat 6 can move forward and backward through the thread, it is matched with the threaded pressure ring 8 designed in the present invention. The thread specifications of the threaded pressure ring 8 are matched with the secondary mirror seat 6, and a clamping groove is designed on the rear end surface of the threaded pressure ring 8 to ensure that the pressure ring wrench can use the clamping groove to fasten the secondary mirror seat 6 to the connecting ring 4 of the secondary mirror bracket 7. At the same time, the secondary mirror seat 6 can be tightened by the threaded pressure ring 8 to obtain the secondary mirror assembly 17. Then, the secondary mirror assembly 17 is directly connected to the main mirror seat 2 of the main mirror assembly through the fastening screws, and the adjustment gasket is removed. The adjustment of the air gap between the main and secondary mirrors is guaranteed by screwing in the thread of the secondary mirror seat 6.
[0027] A method for assembling and adjusting a coaxial reflective optical system, comprising: S1. Centering and assembling the primary mirror assembly; like Figure 5As shown, the main mirror 1 of the main mirror assembly is placed in the main mirror seat 2 and fixed on the air-floating turntable 10; the fitting spherical center image circle drawing amount of the main mirror 1 is observed by the centering instrument 11, the end jump value of the main mirror 1 is detected by the chromatic aberration displacement sensor 12, and the adjustment screw 9 on the main mirror seat 2 is adjusted so that the fitting spherical center image circle drawing amount and the end jump value of the main mirror 1 meet the centering requirements; the adjustment screw 9 is removed, and the glue is injected and cured, wherein the centering requirements are: the fitting spherical center image circle drawing amount ≤0.01mm, and the end jump ≤0.01mm.
[0028] S2, assemble and adjust the primary mirror assembly to establish an assembly reference for the optical system; like Figure 6 As shown, a large-aperture laser interferometer 13 is placed horizontally; a three-dimensional translation adjustment platform 15 and a two-dimensional angle adjustment platform 16 are placed in sequence in the working area of the large-aperture laser interferometer 13; a standard sphere 14 is mounted on the three-dimensional translation adjustment platform 15, and a primary mirror assembly is mounted on the two-dimensional angle adjustment platform; the two-dimensional angle adjustment platform 16 is roughly adjusted to make the primary mirror assembly enter the light-transmitting envelope aperture of the large-aperture laser interferometer 13; the three-dimensional translation adjustment platform 15 is adjusted to make the center of the standard sphere 14 coincide with the focus of the primary mirror assembly; the position of the standard sphere 14 is finely adjusted, that is, the standard sphere 14 is translated up, down, left, and right, and the azimuth angle and pitch angle of the two-dimensional angle adjustment platform 16 are finely adjusted to make the coma term of the wavefront Zernike coefficient of the primary mirror assembly less than 0.02 mm. At this time, the position of the primary mirror assembly is the assembly reference of the entire optical system.
[0029] S3, assembling and adjusting the secondary mirror assembly; like Figure 7 As shown, the secondary mirror assembly 17 is placed between the primary mirror assembly and the large-aperture laser interferometer 13 after the assembly reference is established; the annular frame 3 of the secondary mirror assembly 17 is connected to the primary mirror seat 2 of the primary mirror assembly; the three-dimensional translation adjustment platform 15 and the standard ball 14 thereon are placed at the primary imaging point on the side of the primary mirror assembly away from the secondary mirror assembly 17, and the center of the standard ball 14 coincides with the focal position after reflection of the secondary mirror assembly 17; the position of the standard ball 14 is fine-tuned, that is, the standard ball 14 is translated up and down and left and right, and the translation and tilt of the secondary mirror 5 in the secondary mirror assembly 17 are fine-tuned, and the air gap between the primary and secondary mirrors is adjusted by twisting the secondary mirror seat 6 until the wavefront Zernike coefficient astigmatism, coma and spherical aberration of the optical system are less than 0.02 mm, and the optical system is assembled and adjusted.
[0030] S4, bonding and curing; After the optical system is assembled and adjusted, epoxy resin glue is applied between the connecting ring 4 of the secondary mirror bracket 7 and the secondary mirror seat 6 for bonding and curing; the secondary mirror seat 6 is fastened with the threaded pressing ring 8, and the threads of the threaded pressing ring 8 are coated with thread locking agent; the fastening screws on the secondary mirror seat 6 are removed, and silicone rubber is poured into the screw holes for curing.
[0031] S5. Test and verify to determine the final optical system; The assembled optical system is subjected to stress release tests in high temperature and low temperature environments respectively. Figure 7 As shown, the wavefront of the optical system is re-checked. After the re-check meets the total wavefront RMS index, the total wavefront RMS index is wavefront RMS≤0.08λ, where λ is the wavelength of 632.8nm; if it is not satisfied, repeat steps 3-5 until the re-check meets the total wavefront RMS index, and the final optical system adjustment is completed.
[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A coaxial reflective optical system, comprising a primary mirror assembly and a secondary mirror assembly (17) connected to a mirror seat of the primary mirror assembly, characterized in that: The secondary mirror assembly (17) comprises: A secondary mirror bracket (7), the middle of which is threadedly connected to a secondary mirror seat (6), and the secondary mirror (5) is installed in the secondary mirror seat (6); And a threaded pressing ring (8) is used to press the secondary mirror seat (6).
2. A coaxial reflective optical system according to claim 1, characterized in that: The secondary mirror bracket (7) comprises: an annular frame (3) and a connecting ring (4) arranged concentrically with the annular frame (3); the connecting ring (4) and the annular frame (3) are connected via ribs; the connecting ring (4) is connected to the secondary mirror seat (6) and the threaded pressing ring (8) via threads; and the annular frame (3) is provided with a plurality of mounting holes for connecting to the primary mirror seat (2) of the primary mirror assembly.
3. A coaxial reflective optical system according to claim 2, characterized in that: The threaded pressing ring (8) is provided with a clamping groove, and the clamping groove is used for clamping with the pressing ring wrench.
4. The coaxial reflective optical system according to claim 1, characterized in that: A fastening screw is provided on the secondary mirror seat (6), and the fastening screw is passed through the secondary mirror seat (6) and is used to tighten the secondary mirror (5).
5. A method for assembling a coaxial reflective optical system, characterized in that: Centering and assembling the primary mirror assembly; Laser interference wave aberration method is used to adjust the primary mirror assembly to establish the assembly benchmark of the optical system; The secondary mirror assembly (17) is assembled and adjusted according to the assembly reference of the optical system; Bonding and curing the primary mirror assembly and the secondary mirror assembly of the optical system, and bonding and curing the secondary mirror assembly (17); A stress release test is performed, and after the test, the wavefront of the optical system is re-checked. After the re-check meets the total wavefront RMS index, the final assembly and adjustment of the optical system is completed.
6. The method for assembling and adjusting a coaxial reflective optical system according to claim 5, characterized in that: The steps for centering and assembling the primary mirror assembly are: Placing a primary mirror (1) of the primary mirror assembly in a primary mirror seat (2) and fixing it on an air-floating turntable (10); The amount of the fitted spherical center image drawn circle of the primary mirror (1) is observed by a centering instrument (11), the end jump value of the primary mirror (1) is detected by a chromatic aberration displacement sensor (12), and the adjustment screw (9) on the primary mirror base (2) is adjusted so that the amount of the fitted spherical center image drawn circle and the end jump value of the primary mirror (1) meet the centering requirements; Remove the adjusting screw (9) and cure the injected glue.
7. The method for assembling and adjusting a coaxial reflective optical system according to claim 5, characterized in that: The steps of adjusting the primary mirror assembly using the laser interference wave aberration method to establish the assembly reference of the optical system are as follows: A large-aperture laser interferometer (13) is placed horizontally; A three-dimensional translation adjustment table (15) and a two-dimensional angle adjustment table (16) are sequentially placed in the working area of the large-aperture laser interferometer (13); A standard ball (14) is mounted on a three-dimensional translation adjustment platform (15), and a primary mirror assembly is mounted on a two-dimensional angle adjustment platform; Coarsely adjusting the two-dimensional angle adjustment stage (16) so that the primary mirror assembly enters the light-transmitting envelope aperture of the large-aperture laser interferometer (13); Adjusting the three-dimensional translation adjustment stage (15) so that the center of the standard sphere (14) coincides with the focus of the primary mirror assembly; The position of the standard ball (14) is finely adjusted, and the azimuth angle and the pitch angle of the two-dimensional angle adjustment stage (16) are finely adjusted so that the coma term of the wavefront Zernike coefficient of the primary mirror assembly is less than 0.02 mm. At this time, the position of the primary mirror assembly is the assembly reference of the entire optical system.
8. The method for assembling and adjusting a coaxial reflective optical system according to claim 7, characterized in that: The steps of assembling and adjusting the secondary mirror assembly (17) according to the assembly reference of the optical system are as follows: Placing the secondary mirror assembly (17) between the primary mirror assembly and the large-aperture laser interferometer (13) after the assembly reference is established; Connecting the annular frame (3) of the secondary mirror assembly (17) and the primary mirror base (2) of the primary mirror assembly; Placing the three-dimensional translation adjustment stage (15) and the standard ball (14) thereon at a primary imaging point on the side of the primary mirror assembly facing away from the secondary mirror assembly (17), and making the center of the standard ball (14) coincide with the focal position of the secondary mirror assembly (17) after reflection; The position of the standard sphere (14) is finely adjusted, and the translation and tilt of the secondary mirror (5) in the secondary mirror assembly (17) are finely adjusted. The air interval between the primary and secondary mirrors is adjusted by twisting the secondary mirror seat (6) until the wavefront Zernike coefficient astigmatism, coma and spherical aberration of the optical system are less than 0.02 mm, thereby completing the installation and adjustment of the optical system.
9. The method for assembling and adjusting a coaxial reflective optical system according to claim 5, characterized in that: The steps of bonding and curing the primary mirror assembly and the secondary mirror assembly of the optical system are as follows: after the optical system is assembled and adjusted, epoxy resin glue is applied between the connecting ring (4) of the secondary mirror bracket (7) and the secondary mirror seat (6) for bonding and curing.
10. The method for assembling and adjusting a coaxial reflective optical system according to claim 5, characterized in that: The steps of bonding and curing the secondary mirror assembly (17) are as follows: using a threaded pressing ring (8) to fasten the secondary mirror seat (6), and applying a thread locking agent to the threads of the threaded pressing ring (8); removing the fastening screws on the secondary mirror seat (6), and injecting silicone rubber into the screw holes for curing.