A combined measurement method for initial alignment of an optical-mechanical system

Abstract

The application discloses a combined measurement method for initial assembly and adjustment of an optical machine system, and relates to the technical field of optical machine system assembly and adjustment.The combined measurement method is applied to a combined measurement system.The combined measurement system comprises a laser tracker, three theodolites and a PSM assembly and adjustment microscope.The combined measurement method comprises the following steps: placing a target module at a theoretical position according to mechanical positioning; establishing a global coordinate system through the laser tracker, and determining the spatial coordinates of the curvature center of the target module in the global coordinate system; placing a cooperative target ball of the laser tracker at the spatial coordinates position of the curvature center of the target module; adjusting the PSM assembly and adjustment microscope to be autocollimation with the cooperative target ball of the laser tracker; adjusting the position of the target module based on a global measurement network formed by the three theodolites and the laser tracker, so that the curvature center of the target module coincides with the focal point of the objective lens of the PSM assembly and adjustment microscope, and the final position of the target module is determined.The application improves the initial assembly and adjustment efficiency.

Description

Technical Field

[0001] This invention relates to the field of optomechanical systems technology, and in particular to a combined measurement method for the initial assembly and adjustment of an optomechanical system. Background Technology

[0002] Large and complex optomechanical systems are widely used in high-precision fields such as aerospace and photolithography. Due to their extremely precise structure, large size, and numerous internal modules, the assembly accuracy of large and complex optomechanical systems is one of the important parameters affecting their imaging quality and performance indicators. During the assembly stage of the various modules in a large and complex optomechanical system, if there is any misalignment in the entire system, it will cause increased aberrations, decreased imaging quality, and loss of target details. Therefore, high-precision optical inspection instruments are required for assembly and adjustment.

[0003] Large and complex optomechanical systems require specific assembly and adjustment techniques for initial setup before they can function properly. Currently, the initial setup and adjustment of large and complex optomechanical systems is generally completed manually by experienced technicians using relevant optical testing instruments, relying on their experience and intuition. Typically, a laser tracker is used to establish a reference, a theodolite is used with a plane mirror to calibrate the system's optical axis, the theodolite is then used to adjust the angles of the modules to be assembled, and an interferometer is used to monitor the surface shape of the modules. In common optomechanical system setup and adjustment schemes, relying solely on mechanical positioning results in untraceable measurement data, a lack of communication between instruments, relatively independent data, and poor data consistency. This leads to low efficiency in the initial setup and adjustment process, requiring multiple adjustments to ensure proper positioning. This results in low positioning accuracy for individual modules within the large and complex optomechanical system, introducing numerous errors during assembly. Furthermore, improper operation can damage the surface of modules within the system, significantly impacting imaging quality and accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a combined measurement method for the initial assembly and adjustment of an optomechanical system, which improves the efficiency of initial assembly and adjustment and reduces human error introduced during assembly.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A combined measurement method for initial assembly and adjustment of an optomechanical system, the combined measurement method employing a combined measurement system; the combined measurement system includes: a laser tracker, a first theodolite, a second theodolite, a third theodolite, and a PSM assembly and adjustment microscope;

[0007] The combined measurement method includes:

[0008] The target module is placed at its theoretical position using mechanical positioning; the target module includes a mirror.

[0009] A global coordinate system is established using the laser tracker, and the spatial coordinates of the curvature center of the target module under the global coordinate system are determined.

[0010] Place the cooperative target ball of the laser tracker at the spatial coordinate position of the center of curvature of the target module;

[0011] Adjust the PSM-equipped microscope to autocollimate the cooperative target sphere of the laser tracker;

[0012] A global measurement network is constructed based on the first theodolite, the second theodolite, the third theodolite, and the laser tracker;

[0013] Based on the global measurement network, the position of the target module is adjusted so that the center of curvature of the target module coincides with the focal point of the objective lens of the PSM-mounted microscope, thus determining the final position of the target module.

[0014] Optionally, a global coordinate system is established using the laser tracker, and the spatial coordinates of the curvature center of the target module under the global coordinate system are determined, specifically including:

[0015] A global coordinate system is established by measuring and setting up reference points at multiple stations using the laser tracker.

[0016] The spatial coordinates of the center of curvature of the target module in the global coordinate system are obtained using the laser tracker.

[0017] Optionally, the spatial coordinates of the center of curvature of the target module in the global coordinate system are obtained through the laser tracker, specifically including:

[0018] Point cloud data is obtained by scanning the surface of the mirror on the target module using the laser tracker;

[0019] After removing redundant data from the point cloud data, smoothing processing is performed.

[0020] Select three points from the smoothed surface;

[0021] Calculate the normal vectors of the three points;

[0022] The focus of the normal vectors of the three points is taken as the spatial coordinates of the center of curvature.

[0023] Optionally, a global measurement network is constructed based on the first theodolite, the second theodolite, the third theodolite, and the laser tracker, specifically including:

[0024] The first theodolite, the second theodolite, and the third theodolite are networked together and the locations of the established transfer stations are obtained using the intersection measurement principle.

[0025] Based on the location of the transfer station, the first theodolite, the second theodolite, the third theodolite, and the laser tracker form a global measurement network.

[0026] Optionally, before constructing a global measurement network based on the first theodolite, the second theodolite, the third theodolite, and the laser tracker, the method further includes:

[0027] The first theodolite is self-collimated with the tooling reflector on the back of the target module, the second theodolite is self-collimated with the first reflecting surface of the cubic prism set above the target module, and the third theodolite is self-collimated with the second reflecting surface of the cubic prism; the first reflecting surface and the second reflecting surface are perpendicular to each other.

[0028] Optionally, the final position of the target module includes the spatial coordinates of the curvature center in the global coordinate system, the optical axis direction, and the cubic mirror coordinate system.

[0029] Optionally, the combined measurement system further includes an interferometer;

[0030] The interferometer is used to measure the initial assembly accuracy of the optomechanical system after all target modules in the optomechanical system have been initially assembled and adjusted using the combined measurement method.

[0031] Optionally, the interferometer is used to measure the initial assembly accuracy of the optomechanical system after all target modules in the optomechanical system have undergone initial assembly and adjustment using the combined measurement method, specifically including:

[0032] The light emitted by the interferometer passes through the optomechanical system to a plane mirror and is reflected. The reflected light then passes through the optomechanical system back to the interferometer and interferes.

[0033] The interferometer is used to determine the initial assembly and adjustment accuracy of the optomechanical system based on the wavefront aberration between the emitted light and the received reflected light.

[0034] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0035] This invention establishes a global coordinate system using a laser tracker. Based on this global coordinate system, a global measurement network is constructed using a first theodolite, a second theodolite, a third theodolite, and a laser tracker. All measurement data involved are absolute values ​​in the global coordinate system, which improves the efficiency of initial assembly and adjustment. The invention also introduces a PSM assembly and adjustment microscope to ensure that the curvature center of the target module coincides with the objective lens focus of the PSM assembly and adjustment microscope, thereby determining the final position of the target module and reducing human error introduced during assembly. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of a combined measurement method for initial assembly and adjustment of an optomechanical system provided by an embodiment of the present invention;

[0038] Figure 2 This invention provides a schematic diagram of a combined measurement principle for the initial assembly and adjustment of an optomechanical system.

[0039] Figure 3 This is a schematic diagram of the combined measurement system structure provided in an embodiment of the present invention;

[0040] Figure 4 A schematic diagram illustrating the principle of establishing a global coordinate system for a laser tracker provided in this embodiment of the invention;

[0041] Figure 5 This is a schematic diagram of wavelet aberration detection provided in an embodiment of the present invention.

[0042] Symbol explanation:

[0043] 1-Laser tracker, 2-First theodolite, 3-Second theodolite, 4-Third theodolite, 5-PSM-mounted microscope, 6-Interferometer, 7-Target module, 8-Plane mirror. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] The purpose of this invention is to provide a combined measurement method for the initial assembly and adjustment of an optomechanical system, which improves the efficiency of initial assembly and adjustment and reduces human error introduced during assembly.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] like Figure 1 and Figure 2 As shown, this embodiment provides a combined measurement method for the initial assembly and adjustment of an optomechanical system, wherein the combined measurement method utilizes a combined measurement system; as shown Figure 3 The combined measurement system shown includes: a laser tracker 1, a first theodolite 2, a second theodolite 3, a third theodolite 4, and a PSM-equipped microscope 5.

[0048] In this combined measurement system, laser tracker 1 is used to construct a global coordinate system. To achieve synchronous collaboration among the various optical inspection instruments, laser tracker 1 is needed to establish accurate relative positional relationships between them. This involves multi-station measurement via a laser tracking system, where different stations share common transfer points. Measurement data from each station is fused based on a unified spatial network, such as... Figure 4 As shown, a global coordinate system is established, a high-precision measurement field is built, and the benchmark of each independent coordinate system is unified.

[0049] Among them, O M1 O M2 O M3 and O M4 O is the common measurement point for laser tracker 1 to perform measurements at different sites. G Using the origin of the global coordinate system, the measurement results from the local coordinate system (i.e., the single-station measurement system) are transformed into the global coordinate system, thus unifying the data from various local coordinate systems into the global coordinate system and achieving data fusion. This is because the data from the subsequent assembly of mirrors, i.e., other target modules, in this local coordinate system is aligned to the global coordinate system, and the measurement data is fused into the global coordinate system.

[0050] The first theodolite 2, the second theodolite 3, the third theodolite 4, and the laser tracker 1 form a global measurement network. When more complex and large-scale measurement tasks are required, network measurement can rationally arrange multiple measurement devices throughout the entire measurement area, and perform precise calculations and analyses on the data obtained through mutual measurements, thereby obtaining higher accuracy measurement results.

[0051] To establish a global measurement network, the first theodolite 2, the second theodolite 3, the third theodolite 4, and the laser tracker 1 need to determine one or more stable reference points and confirm and calibrate their positions and coordinates. The first theodolite 2, the second theodolite 3, and the third theodolite 4 are cross-aligned and networked, and the positions of the established transfer stations are obtained using the intersection measurement principle, thus forming a global measurement network with the laser tracker 1.

[0052] The PSM assembly and adjustment microscope 5 is a general-purpose assembly and adjustment microscope suitable for assembling and adjusting large and complex optomechanical systems. Its function is to effectively determine the curvature center position of the surface of each module in a large and complex optomechanical system, thereby completing the collimation of the optical axis of the large and complex optomechanical system.

[0053] Interferometer 6 utilizes the phenomenon and principle of light interference to perform precision measurements. After the initial assembly and adjustment, interferometer 6 detects the interference wavefront data, observes the interference pattern of the large and complex optomechanical system under test, and analyzes whether the assembly and adjustment are qualified by observing the symmetry, uniformity, and clarity of the interference fringes. After assembling the large and complex optomechanical system into the determined final position, the wavefront aberration of all modules is detected by the self-collimating interferometry method.

[0054] For general optical systems, the combined measurement system built using the aforementioned instruments assembles and adjusts each module according to the optical path sequence of the mirror groups within the optical system. For some large and complex optomechanical systems, such as off-axis systems, the most "sensitive" mirror in the mirror group is installed first as the reference, that is, the module with the greatest impact on the optomechanical system is installed first to improve the efficiency of subsequent assembly and adjustment. In practical applications, the assembly and adjustment order of each module is specifically set according to the structure, complexity, and specific application of the optomechanical system.

[0055] The module currently undergoing initial assembly is designated as target module 7. Target module 7 is a mirror (front), with a plane mirror mounted on its back and a cubic prism placed on top of it.

[0056] The combined measurement method includes:

[0057] Step 101: Place the target module 7 at the theoretical position according to the mechanical positioning; the target module 7 includes a mirror.

[0058] After placing the target module 7 at the theoretical position, the stability of the target module 7 must be ensured.

[0059] Step 102: Establish a global coordinate system using the laser tracker 1, and determine the spatial coordinates of the curvature center of the target module 7 under the global coordinate system.

[0060] Step 102 specifically includes:

[0061] The laser tracker 1 is used to set up reference points for multiple stations and establish a global coordinate system. Specifically, this includes: placing the laser tracker 1 at the optimal station position that can measure all the target seats set up on the target module 7 according to the measurement task and measurement environment constraints, setting up reference points for multiple stations, and establishing a global coordinate system based on the reference point data of multiple stations.

[0062] The spatial coordinates of the curvature center of the target module 7 in the global coordinate system are obtained through the laser tracker 1, specifically including:

[0063] The position of the target module 7 in the global coordinate system is obtained by measuring the target base deployed on the target module 7.

[0064] Point cloud data is obtained by scanning the surface of the mirror on the target module 7 using the laser tracker 1.

[0065] After removing redundant data from the point cloud data, smoothing processing is performed.

[0066] Select three points from the smoothed surface. These three points form a stable plane.

[0067] Calculate the normal vectors of the three points.

[0068] Fit the focus of the normal vectors of the three points to obtain the spatial coordinates of the curvature center of the target module 7.

[0069] Step 103: Place the cooperative target ball of the laser tracker 1 at the spatial coordinate position of the curvature center of the target module 7.

[0070] Step 104: Adjust the PSM-equipped microscope 5 to autocollimate with the cooperative target ball of the laser tracker 1.

[0071] Specifically, step 104 further includes: after removing the cooperative target ball from the laser tracker 1, the detector of the PSM assembly microscope 5 can receive the image of the curvature center of the target module 7. Since the target module 7 is not assembled to the precise position required by the optical design in this state, the curvature center of the target module 7 seen on the detector of the PSM assembly microscope 5 cannot be focused into a small point. Therefore, in order to accurately locate the position of the target module 7, it is necessary to use a theodolite for measurement and monitoring.

[0072] The process between step 104 and step 105 also includes:

[0073] The first theodolite 2 is self-collimated with the tooling reflector on the back of the target module 7; the second theodolite 3 is self-collimated with the first reflecting surface of the cubic prism set above the target module 7; and the third theodolite 4 is self-collimated with the second reflecting surface of the cubic prism. The first reflecting surface and the second reflecting surface are perpendicular to each other.

[0074] Step 105: Construct a global measurement network based on the first theodolite 2, the second theodolite 3, the third theodolite 4, and the laser tracker 1.

[0075] Step 105 specifically includes:

[0076] The first theodolite 2, the second theodolite 3, and the third theodolite 4 are networked together, and the locations of the already deployed transfer stations are obtained using the intersection measurement principle.

[0077] Based on the location of the transfer station, the first theodolite 2, the second theodolite 3, the third theodolite 4, and the laser tracker 1 form a global measurement network.

[0078] Step 106: Based on the global measurement network, adjust the position of the target module 7 so that the center of curvature of the target module 7 coincides with the objective lens focus of the PSM-mounted microscope 5, and determine the final position of the target module 7.

[0079] Step 106 specifically includes: In the global coordinate system, the axial direction of the tooling reflector can be located, thus determining the optical axis direction of the target module 7, and the coordinate system of the cubic mirror can also be measured; the normal of the tooling reflector on the back of the target module 7 is monitored using the first theodolite 2 to ensure that the normal direction remains unchanged; the position of the target module 7 is adjusted so that the center of curvature of the target module 7 coincides with the focal point of the objective lens of the PSM assembly microscope 5, thus determining the final position of the target module 7; the target point on the frame of the target module 7 is re-measured using the laser tracker 1, and the position of the center of curvature, the optical axis direction, and the coordinate system of the cubic mirror are matched to the position of the target point after the target module 7 is moved, obtaining the correct position of the center of curvature of the target module 7 in the global coordinate system. Thus, in the global coordinate system, the position of the center of curvature of the target module 7 before and after movement, the optical axis direction, and the coordinate system of the cubic mirror are known. The accuracy of the mechanical positioning is evaluated by comparing the spatial position change between the center of curvature obtained by fitting the surface data of the target module 7 using the laser tracker 1 and the center of curvature accurately positioned using the PSM assembly microscope 5 after moving the target module 7.

[0080] Following the steps outlined above, using target module 7 as a reference, all modules of the large and complex optomechanical system were assembled and adjusted using a combined measurement method.

[0081] The final position of the target module 7 includes the spatial coordinates of the curvature center in the global coordinate system, the direction of the optical axis, and the coordinate system of the cubic mirror.

[0082] The combined measurement system also includes an interferometer 6.

[0083] The interferometer 6 is used to measure the initial assembly accuracy of the optomechanical system after each target module 7 in the optomechanical system has been initially assembled and adjusted using the combined measurement method.

[0084] The interferometer 6 is used to measure the initial assembly accuracy of the optomechanical system after all target modules 7 in the optomechanical system have undergone initial assembly and adjustment using the combined measurement method. Specifically, this includes:

[0085] The light emitted by the interferometer 6 passes through the optomechanical system to a plane mirror 8 and is reflected. The reflected light then passes through the optomechanical system back to the interferometer 6 and interferes.

[0086] The interferometer 6 is used to determine the initial assembly and adjustment accuracy of the optomechanical system based on the wavefront aberration of the emitted light and the received reflected light. Specifically, after the initial assembly and adjustment of the large and complex optomechanical system is completed, interference fringes will appear on the software configured on the interferometer 6. After further analysis based on the software configured on the interferometer 6, the initial assembly and adjustment accuracy is obtained.

[0087] The above assembly and adjustment steps can adjust the initial positions of each module in a large and complex optomechanical system, providing a foundation for subsequent precision assembly and adjustment. A laser tracker establishes a global coordinate system, acquiring the spatial position of the curvature center of each target module before and after micro-adjustment within this system. The laser tracker and theodolite form a global measurement network, which can measure the optical axis direction of each module before and after micro-adjustment, as well as the change in the cubic mirror coordinate system. Further comparison of the spatial positions of the mechanical positioning modules and the modules after adjustment by the combined measurement system allows for analysis to determine the initial assembly and adjustment accuracy.

[0088] Compared to existing technologies, the beneficial technical effects of this invention are as follows: In the initial assembly and adjustment stage of large and complex optomechanical systems, a combined measurement system is established, ensuring initial assembly and adjustment accuracy while significantly improving the efficiency of initial assembly and adjustment, and reducing human error introduced during assembly. During the initial assembly and adjustment process, the measurement data are global data, and the data are absolute values, not relative values. A laser tracker and a theodolite form a measurement network, and the measurement data is traceable. The pose of each module is adjusted in a timely manner during the initial assembly and adjustment process, greatly improving efficiency. The combined measurement system has strong versatility and can be used in the initial assembly and adjustment stage of various large and complex optomechanical systems.

[0089] This invention addresses the initial assembly and adjustment of large and complex optomechanical systems. It utilizes a laser tracking system, a theodolite, a PSM assembly microscope, and an interferometer to construct a combined measurement system. This combined measurement system is highly versatile, with interconnected instruments based on a global coordinate system. Measurement data is traceable, allowing for timely adjustment of the positions of various modules within the large and complex optomechanical system. This improves the efficiency of initial assembly and adjustment while ensuring accuracy, reducing the introduction of human error, and ensuring that each module is within the tolerances of the optical design. The interferometer detects wavefront aberrations, quickly producing interference fringes, providing a necessary foundation for subsequent computer-aided precision assembly and adjustment of the entire large and complex optomechanical system.

[0090] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0091] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A combined measurement method for initial assembly and adjustment of an optomechanical system, characterized in that, The combined measurement method utilizes a combined measurement system; The combined measurement system includes: a laser tracker, a first theodolite, a second theodolite, a third theodolite, and a PSM-mounted microscope; The combined measurement method includes: The target module is placed at its theoretical position using mechanical positioning; the target module includes a mirror. The process of establishing a global coordinate system using the laser tracker and determining the spatial coordinates of the curvature center of the target module within this global coordinate system includes: establishing a global coordinate system by measuring and setting up reference points at multiple stations using the laser tracker; scanning the surface of the mirror on the target module using the laser tracker to obtain point cloud data; removing redundant data from the point cloud data and then smoothing it; selecting three points from the smoothed surface; calculating the normal vectors of the three points; and using the focus of the normal vectors of the three points as the spatial coordinates of the curvature center. Place the cooperative target ball of the laser tracker at the spatial coordinate position of the center of curvature of the target module; Adjust the PSM-equipped microscope to autocollimate the cooperative target sphere of the laser tracker; The global measurement network is constructed based on the first theodolite, the second theodolite, the third theodolite, and the laser tracker, specifically including: mutually aiming the first theodolite, the second theodolite, and the third theodolite into a network, and using the intersection measurement principle to obtain the locations of the already deployed turning points; based on the locations of the turning points, the first theodolite, the second theodolite, the third theodolite, and the laser tracker are used to construct a global measurement network; Based on the global measurement network, the position of the target module is adjusted so that the center of curvature of the target module coincides with the focal point of the objective lens of the PSM-mounted microscope, thus determining the final position of the target module.

2. The combined measurement method for initial assembly and adjustment of an optomechanical system according to claim 1, characterized in that, Before constructing a global measurement network based on the first theodolite, the second theodolite, the third theodolite, and the laser tracker, the following steps are also included: The first theodolite is self-collimated with the tooling reflector on the back of the target module, the second theodolite is self-collimated with the first reflecting surface of the cubic prism set above the target module, and the third theodolite is self-collimated with the second reflecting surface of the cubic prism; the first reflecting surface and the second reflecting surface are perpendicular to each other.

3. The combined measurement method for initial assembly and adjustment of an optomechanical system according to claim 2, characterized in that, The final position of the target module includes the spatial coordinates of the curvature center in the global coordinate system, the optical axis direction, and the cubic mirror coordinate system.

4. The combined measurement method for initial assembly and adjustment of an optomechanical system according to claim 1, characterized in that, The combined measurement system also includes an interferometer; The interferometer is used to measure the initial assembly accuracy of the optomechanical system after all target modules in the optomechanical system have been initially assembled and adjusted using the combined measurement method.

5. The combined measurement method for initial assembly and adjustment of an optomechanical system according to claim 4, characterized in that, The interferometer is used to measure the initial assembly accuracy of the optomechanical system after all target modules in the system have undergone initial assembly and adjustment using the combined measurement method. Specifically, this includes: The light emitted by the interferometer passes through the optomechanical system to a plane mirror and is reflected. The reflected light then passes through the optomechanical system back to the interferometer and interferes. The interferometer is used to determine the initial assembly and adjustment accuracy of the optomechanical system based on the wavefront aberration between the emitted light and the received reflected light.

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