Device and method for high-precision in-situ detection of large-aperture optical components over the entire frequency band

Abstract

The present invention relates to the field of optical processing technology, and in particular to a device and method for high-precision on-site detection of large-aperture optical elements in the full frequency band. The device comprises a processing execution device, a quick-change tool station, a swing arm measuring device, a coordinate probe measuring device, a non-contact measuring device and a polishing tool group. In the process of switching between processing and detection modes, it is not necessary to change the position of the optical element, and it is only necessary to manipulate the switchable connection between the processing execution device and the swing arm measuring device, the coordinate probe measuring device and the polishing tool group to quickly switch the working state. In the method, the swing arm measuring device and the coordinate probe measuring device are used for interactive measurement, the non-contact measuring device is used to monitor the motion error of the processing execution device, and the measurement result of the coordinate probe measuring device is corrected, so as to obtain a defocus value accurate to the micron level, and combined with the detection result of the swing arm measuring device, high-precision contour detection of full-frequency band optical elements from the millimeter level to the micron level is realized.

Description

Technical Field

[0001] The present invention belongs to the field of optical processing technology, and in particular relates to a device and method for high-precision on-site detection of large-aperture optical elements over the entire frequency band. Background Art

[0002] In the advanced optical processing system, large-diameter optical components go through multiple processes such as milling, grinding, and polishing from mirror blanks to finished optical components. It is a systematic project that combines multiple high-precision detection and deterministic removal methods. Because the processing precision is extremely high, optical processing is actually an iterative convergence process of surface shape errors. In this process, the processing results need to be tested with high precision after each round of processing, so as to adjust the methods and process parameters of the next processing. The detection methods can be roughly divided into two types, namely contour detection and optical interference detection. The surface quality of optical components is poor in the milling and grinding stage, the reflectivity is insufficient, and there is no optical detection condition. Only detection methods similar to those in the traditional mechanical processing field can be used, such as coordinate measuring machines (CMMs), laser trackers, etc. This stage can be collectively referred to as the contour detection stage. Optical component milling, grinding, rough polishing and other processes are all in the contour detection stage. At this stage, traditional detection methods often require the components to be unloaded from the processing equipment, transported to the measuring equipment for detection, and then transported back to the processing equipment for installation and a new round of processing after the detection is completed. Large-aperture optical components are bulky and heavy. This transportation process not only wastes a lot of time, but also brings the risk of safety accidents and unavoidable positioning errors, which has an adverse impact on the precision optical processing of the reflector.

[0003] Therefore, combining measurement equipment with processing equipment to achieve on-site measurement is an effective means to solve the above problems. However, due to the fact that the motion accuracy of processing equipment usually does not meet the measurement accuracy requirements, many conventional measurement methods are difficult to implement effectively.

[0004] At present, there are several related solutions for the in-situ measurement of optical components at home and abroad:

[0005] The Chinese patent publication number is CN117213369A, the publication date is December 12, 2023, and the patent name is "A method for measuring the surface shape of optical components based on a laser tracker combined with a robotic arm". The robotic arm uses the floating target to pull the laser tracker to measure the surface shape of the optical component. First, the measurement accuracy limit of the laser tracker is only on the order of 10 microns, and secondly, the movement accuracy limit of the robotic arm can only reach the sub-micron level. This measurement method is difficult to meet the requirements of micron-level measurement accuracy and can only meet the measurement requirements of the milling stage.

[0006] The Chinese patent publication number is CN116330089A, the publication date is June 27, 2023, and the patent name is "An in-situ measurement time-controlled grinding device and its measurement method". The invention patent application has a measurement platform on the processing equipment. The first measurement is used to compensate for the error, and the second measurement is used to obtain the surface data. The integration of processing and detection is achieved through self-compensation. This measurement method can eliminate the systematic error of the machine tool itself. However, because the accuracy requirements of optical component processing far exceed those of mechanical processing, the repeatability errors of the processing equipment will seriously interfere with the detection results of the surface errors of optical components. Therefore, this method can only be used in the grinding stage with lower precision, and the detection capability is not enough to cover the entire contour detection stage.

[0007] The Chinese patent publication number is CN110243306A, the publication date is September 17, 2019, and the patent name is "Robot-based planar surface shape sub-aperture stitching interference measurement device and method". The invention patent application uses a robot-clamped interferometer to perform sub-aperture measurement, and then obtains the surface shape accuracy through stitching. This method requires that the surface quality of the optical element meets the interference detection conditions, so it is only suitable for the polishing stage, and cannot be applied to contour detection in the milling and grinding stages. Similar to this is the Chinese patent publication number CN106595473A, the publication date is April 26, 2017, and the patent name is "In-situ measurement system for aspheric molds, its measurement method and measurement inspection method". Summary of the invention

[0008] In view of this, the present invention aims to provide a device and method for high-precision in-situ detection of large-aperture optical components in the full frequency band, use non-contact measuring equipment to monitor the motion error of the machine tool, correct the measurement results of the coordinate probe measuring device, so that the defocus value accurate to the micron level can be obtained, and combined with the detection results of the swing arm measuring device, high-precision contour detection of optical components in the full frequency band from millimeter level to micron level can be achieved.

[0009] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0010] A full-band high-precision in-situ detection device for large-aperture optical elements comprises a processing execution device, a quick-change tool station, a swing arm measuring device, a coordinate probe measuring device, a non-contact measuring device and a polishing tool group; wherein the optical element is placed on a processing turntable of the processing execution device; the quick-change tool station is integrated on the processing execution device, and the swing arm measuring device, the coordinate probe measuring device and the polishing tool group are arranged on the quick-change tool station; the processing execution device has a processing end, and the processing end is switchably connected to the swing arm measuring device, the coordinate probe measuring device and the polishing tool group; the non-contact measuring device is installed on the processing execution device, and cooperates with the coordinate probe measuring device to complete the measurement of the position coordinates and spatial motion errors of the processing end.

[0011] Furthermore, the swing arm measuring device includes an air-floating turntable, a supporting measuring arm and a displacement sensor; wherein the air-floating turntable and the displacement sensor are respectively located at two ends of the supporting measuring arm; the air-floating turntable is tilted, and the axis of the air-floating turntable passes through the best fitting sphere center of the optical element; the air-floating turntable is connected to the processing end, so that the processing end drives the displacement sensor to rotate around the axis of the air-floating turntable through the air-floating turntable and the supporting measuring arm; during the rotation process, the displacement sensor passes through the geometric center of the optical element.

[0012] Furthermore, the processing end of the processing execution device is switchably connected to the coordinate probe measuring device through a quick-change device, so that the processing end drives the end of the coordinate probe measuring device to contact the surface of the optical element; when the end of the coordinate probe measuring device contacts the surface of the optical element, the coordinate probe measuring device sends a stop motion signal to the processing execution device, and the processing execution device records the machine tool motion coordinates of the current contact point through its own numerical control system.

[0013] Furthermore, the processing execution device is a double-axis gantry machine tool.

[0014] Furthermore, the polishing tool set includes no less than two computer-controlled small grinding head processing tools, and each computer-controlled small grinding head processing tool has a different size.

[0015] A method for detecting a large-aperture optical element in full-band high-precision position, which is applicable to a large-aperture optical element in full-band high-precision position detection device proposed in the present invention, specifically comprises the following steps:

[0016] S1: The processing end grabs the quick-change tool station and drives the swing arm measuring device to move on the surface of the optical element; the swing arm measuring device measures the overall offset between the actual surface morphology of the optical element and the best fitting sphere of the optical element, thereby obtaining the actual surface morphology;

[0017] S2: The processing end puts the swing arm measuring device back to the quick-change tool station, then grabs and drives the coordinate probe measuring device from the quick-change tool station to move it into the measuring range of the non-contact measuring device; the non-contact measuring device cooperates with the coordinate probe measuring device to complete the measurement of the spatial motion error of the processing end;

[0018] S3: The processing end drives the coordinate probe measuring device to contact the optical element point by point along the set measurement trajectory, and records the position coordinates of each contact point; the spatial motion error is compensated to the position coordinates of each contact point, and the new position coordinates of each contact point are obtained, thereby obtaining the coordinate measurement results of the optical element;

[0019] S4: Fit the coordinate measurement results with Zernike polynomials, and then extract the defocus from the fitting results; add the defocus to the actual surface morphology to obtain the final surface error distribution.

[0020] Furthermore, step S1 specifically includes the following steps:

[0021] S11: The processing end drives the displacement sensor to rotate around the axis of the air-floating turntable, so that the probe of the displacement sensor sweeps a circular trajectory on the surface of the optical element; the displacement sensor obtains the offset between the actual surface morphology of the optical element under the current circular trajectory and the best fitting sphere of the optical element according to the current circular trajectory;

[0022] S12: The processing turntable drives the optical element to rotate around the axis of the processing turntable. , and repeat step S11 after the rotation until the optical element rotates one circle, at which time a series of circular tracks and a series of offsets corresponding to the circular tracks are obtained;

[0023] S13: Correcting the overlapping points between a series of circular trajectories to obtain the overall offset, and then adding the overall offset to the best fitting sphere to obtain the actual surface morphology.

[0024] Further, in step S2,

[0025] When the machining end drives the coordinate probe measuring device to move along the X-axis in the machining three-dimensional coordinate system of the machining execution device, the spatial motion errors of the coordinate probe measuring device in the X-axis, Y-axis and Z-axis directions in the machining three-dimensional coordinate system are measured by a non-contact measuring device;

[0026] When the machining end drives the coordinate probe measuring device to move along the Y-axis in the machining three-dimensional coordinate system of the machining execution device, the spatial motion errors of the coordinate probe measuring device in the X-axis, Y-axis and Z-axis directions in the machining three-dimensional coordinate system are measured by the non-contact measuring equipment.

[0027] Furthermore, the center point of the processing three-dimensional coordinate system in step S2 is the surface center of the optical element.

[0028] Furthermore, in step S3, the processing end drives the coordinate probe measuring device to move point by point along the measuring trajectory to the top of the optical element; at each measuring point on the measuring trajectory, the processing end drives the coordinate probe measuring device to press down until the coordinate probe measuring device contacts the surface of the optical element, at which time the coordinate probe measuring device sends a stop motion signal to the processing execution device and records the position coordinates of the current contact point.

[0029] Compared with the prior art, the invention can achieve the following beneficial effects:

[0030] (1) In the large-aperture optical element full-band high-precision in-situ detection device created by the present invention, a processing execution device is used in combination with a swing arm measuring device and a coordinate probe measuring device to perform full-band high-precision in-situ detection of the large-aperture optical element; at the same time, the swing arm measuring device and the coordinate probe measuring device are integrated into the machine tool quick-change module, without the need to unload the workpiece or manual intervention, and the in-situ detection is automatically completed after the processing is completed, thereby improving work efficiency;

[0031] (2) In the method for high-precision in-situ detection of large-aperture optical elements in full frequency bands described in the present invention, a swing arm measuring device and a coordinate probe measuring device are used for interactive measurement to achieve high-precision in-situ detection in full frequency bands from millimeter level to micrometer level; at the same time, based on the spatial motion error of the device measured by the non-contact measuring equipment, the position coordinates of the contact point measured by the coordinate probe measuring device are error compensated to improve the measurement accuracy of the coordinate probe measuring device to micrometer level; finally, the error-compensated position coordinates are fitted with Zernike polynomials, and the defocus amount in the fitting result is extracted, and then the defocus amount is added to the swing arm measurement result, thereby finally achieving high-precision in-situ measurement of optical elements and solving the limitation that the swing arm measurement cannot measure the curvature radius;

[0032] (3) In the method for high-precision in-situ detection of large-aperture optical elements in the full-band, the invention adopts a swing arm measurement method to efficiently obtain dense point coordinate data, and at the same time measures the high-frequency error and low-frequency error of the surface shape, breaking through the limitation that the previous technology can only measure the error of one frequency band;

[0033] (4) The method for high-precision on-site detection of large-aperture optical elements in the full-band frequency range described in the present invention realizes high-precision on-site detection of the full-band frequency range from millimeter level to micrometer level, which can meet the needs of iterative correction of surface errors in the three stages of milling, grinding and rough polishing. Before the optical element enters the optical modification stage, there is no need to adopt any other surface measurement method, which is simple and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0035] Figure 1 A schematic diagram of the structure of a large-aperture optical element full-band high-precision in-situ detection device according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the structure of the swing arm measuring device according to an embodiment of the present invention;

[0037] Figure 3A schematic diagram of the process of the method for high-precision in-situ detection of large-aperture optical components in full frequency bands according to an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the measuring principle of the swing arm measuring device according to an embodiment of the present invention;

[0039] Figure 5 A measurement trajectory diagram of the swing arm measurement device described in an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of the measurement process of the non-contact measurement device according to an embodiment of the present invention;

[0041] Figure 7 A schematic diagram of the spatial motion error compensation amount according to an embodiment of the present invention;

[0042] Figure 8 A measurement trajectory diagram of a coordinate probe measuring device according to an embodiment of the present invention;

[0043] Fig. 9 It is a curve diagram of the spatial motion error when the processing end moves along the X-axis;

[0044] Fig.10 It is a curve diagram of the spatial motion error when the processing end moves along the Y axis;

[0045] Fig.11 Schematic diagram of the process of measuring result processing and superposition.

[0046] Description of reference numerals:

[0047] 1. Processing execution device; 2. Quick-change tool station; 3. Swing arm measuring device; 4. Coordinate probe measuring device; 5. Polishing tool set; 6. Optical element; 7. Air-floating turntable; 8. Support measuring arm; 9. Displacement sensor; 10. Laser transmitter; 11. Laser reflector; 12. Reversing mirror. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0049] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0051] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0052] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0053] like Figure 1 to Figure 2 As shown, the large-aperture optical element full-band high-precision in-situ detection device described in the embodiment of the invention includes a processing execution device 1, a quick-change tool station 2, a swing arm measuring device 3, a coordinate probe measuring device 4, a non-contact measuring device and a polishing tool group 5. Among them, the optical element 6 is placed on the processing turntable of the processing execution device 1, the quick-change tool station 2 is integrated on the processing execution device 1, and the swing arm measuring device 3, the coordinate probe measuring device 4 and the polishing tool group 5 are arranged on the quick-change tool station 2. The processing execution device 1 has a processing end, and the processing end is switchably connected to the swing arm measuring device 3, the coordinate probe measuring device 4 and the polishing tool group 5. The non-contact measuring device is installed on the processing execution device 1, and cooperates with the coordinate probe measuring device 4 to complete the measurement of the position coordinates and spatial motion errors of the processing end.

[0054] The processing execution device 1 in the embodiment of the present invention is not limited by the machine tool configuration, and is applicable to other gantry machine tools that meet the requirements of XYZ three-dimensional motion and circular motion, such as a dual-axis gantry machine tool, a three-axis gantry machine tool, a four-axis gantry machine tool, etc. In the embodiment of the present invention, a dual-axis gantry machine tool is preferably used as the processing execution device 1, and the processing end of the dual-axis gantry machine tool is provided with a quick-change device that can be connected to the swing arm measuring device 3, the coordinate probe measuring device 4 and the polishing tool group 5. At this time, during the switching process of the processing and detection mode, there is no need to change the position of the optical element 6. It is only necessary to operate the processing execution device 1 to replace the swing arm measuring device 3, the coordinate probe measuring device 4 and the polishing tool group 5 through the quick-change device at the processing end, so as to realize the rapid switching state of the processing and detection mode, and realize the full-process automated manufacturing integrating processing and measurement.

[0055] The swing arm measuring device 3 includes an air-floating turntable 7, a supporting measuring arm 8 and a displacement sensor 9. The air-floating turntable 7 and the displacement sensor 9 are respectively located at the two ends of the supporting measuring arm 8. The air-floating turntable 7 is tilted, and the axis of the air-floating turntable 7 passes through the best fitting spherical center of the optical element 6. The best fitting spherical surface of the optical element 6 is a spherical surface with a high degree of fit with the optical element 6 estimated according to the surface shape of the optical element 6 before detection. The best fitting spherical surface can also be generally referred to as the closest spherical surface. The best fitting spherical center of the optical element 6 is the spherical center of the best fitting spherical surface of the optical element 6. The best fitting spherical center is also generally referred to as the closest spherical center. The air-floating turntable 7 is connected to the processing end of the processing execution device 1, so that the processing end drives the displacement sensor 9 to rotate around the axis of the air-floating turntable 7 through the air-floating turntable 7 and the supporting measuring arm 8, and the displacement sensor 9 passes through the geometric center of the optical element 6 during the rotation.

[0056] The processing end of the processing execution device 1 is switchably connected to the coordinate probe measuring device 4 through a quick change device, so that the processing end drives the end of the coordinate probe measuring device 4 to contact the surface of the optical element 6. When the end of the coordinate probe measuring device 4 contacts the surface of the optical element 6, the coordinate probe measuring device 4 sends a stop motion signal to the processing execution device 1, and the processing execution device 1 records the machine tool motion coordinates of the current contact point through its own numerical control system. In the embodiment of the present invention, the coordinate probe measuring device 4 uses a Renishaw coordinate probe, and its end is a ruby.

[0057] The polishing tool set 5 includes at least two computer-controlled small grinding head processing tools, and each computer-controlled small grinding head processing tool has a different size. In the embodiment of the present invention, the polishing tool set 5 includes two computer-controlled small grinding head processing tools of different sizes.

[0058] In the embodiment of the present invention, the non-contact measuring device uses a 6D laser interferometer of the API brand. The interferometer can simultaneously measure six errors of the linear axis in one installation, including 1 position error, 2 straightness errors and 3 angle errors. The interferometer includes a laser emitter 10 and a laser reflector 11, wherein the laser reflector 11 is located on the side of the coordinate probe measuring device 4, and the laser emitter 10 is arranged on one side of the processing execution device 1. When the processing end of the processing execution device 1 drives the coordinate probe measuring device 4 to move in a certain direction, the laser emitter 10 emits a laser to the laser reflector 11, and the laser reflector 11 receives the laser and then reflects it back to the laser emitter 10. The laser emitted by the laser emitter 10 interferes with the received laser in the laser emitter 10. The laser emitter 10 obtains the spatial motion error generated in the X direction, Y direction and Z direction in the processing three-dimensional coordinate system of the processing execution device 1 when the coordinate probe measuring device 4 moves in this direction according to the interference result.

[0059] The present invention also provides a method for high-precision on-site detection of large-aperture optical elements over the entire frequency band, which is applicable to the high-precision on-site detection device for large-aperture optical elements over the entire frequency band described in the embodiments of the present invention.

[0060] like Figures 3 to 11 As shown, the method for high-precision in-situ detection of large-aperture optical elements in full frequency bands described in the embodiment of the present invention specifically includes the following steps:

[0061] S1: The processing end grabs the quick-change tool station 2 and drives the swing arm measuring device 3 to move on the surface of the optical element 6, so that the swing arm measuring device 3 measures the overall offset between the actual surface morphology of the optical element 6 and the best fitting sphere of the optical element 6, and then obtains the actual surface morphology.

[0062] Step S1 specifically includes the following steps:

[0063] S11: The processing end of the processing execution device 1 provides power to rotate the displacement sensor 9 around the axis of the air-floating turntable 7, so that the probe of the displacement sensor 9 sweeps a circular trajectory on the surface of the optical element 6; the displacement sensor 9 obtains the offset between the actual surface morphology of the optical element 6 and the best fitting spherical surface of the optical element 6 under the current circular trajectory according to the current circular trajectory.

[0064] S12: The processing turntable drives the optical element 6 to rotate around the axis of the processing turntable. , and repeat the step S11 after the rotation until the optical element 6 rotates one circle, at which time a series of circular tracks (such as Figure 5 In the embodiment of the present invention, the rotation angle θ is usually set to 5° or 2.5°, and 72 or 144 circular tracks can be obtained on the optical element 6, respectively.

[0065] S13: Correct the overlapping points between a series of circular trajectories to eliminate the error of the processing execution device 1 during the measurement process, obtain the overall offset, and then add the overall offset to the best fitting sphere to obtain the actual surface morphology.

[0066] In the present invention, the swing arm measurement adopts a non-contact displacement sensor to realize the continuous measurement of uniform motion. There is intersection between the measurement results, and the spatial motion error of the processing execution device 1 during the measurement process can be eliminated by overlapping point correction, thereby effectively improving the measurement accuracy and efficiency.

[0067] S2: The processing end puts the swing arm measuring device 3 back to the quick-change tool station 2, then grabs and drives the coordinate probe measuring device 4 from the quick-change tool station 2 to move it into the measuring range of the non-contact measuring equipment; the non-contact measuring equipment cooperates with the coordinate probe measuring device 4 to complete the measurement of the spatial motion error of the processing end.

[0068] Specifically, in step S2, it is necessary to measure the spatial motion error of the end actuator mounted on the processing end when the processing end moves along the X-axis and Y-axis in the processing three-dimensional coordinate system, wherein the coordinate origin of the processing end three-dimensional coordinate system coincides with the geometric center of the optical element 6.

[0069] like Figure 6 As shown in (a), when measuring the spatial motion error of the processing end when it moves along the Y-axis in the processing three-dimensional coordinate system, it is necessary to first complete the optical path debugging part of the non-contact measurement equipment, that is: set the laser emitter 10 in the positive direction of the Y-axis, adjust the position between the laser emitter 10 and the laser reflector 11, and align the optical path of the laser emitter 10 and the laser reflector 11 with the Y-axis direction.

[0070] After completing the optical path debugging part of the non-contact measuring equipment, the spatial motion error measurement part begins, that is, driving the processing execution device 1 so that the processing end drives the coordinate probe measuring device 4 and the laser reflector 11 to move along the Y axis, and at the same time turning on the laser emitter 10. The laser emitted by the laser emitter 10 is reflected back to the laser emitter 10 through the laser reflector 11. The laser emitted by the laser emitter 10 and the received laser interfere with each other in the laser emitter 10, and the straightness and linearity of the Y-axis movement of the processing end are obtained according to the interference result, that is, the spatial motion errors of the processing end in the X-axis, Y-axis and Z-axis directions in the processing three-dimensional coordinate system when the Y-axis moves.

[0071] like Figure 6As shown in (b), when measuring the spatial motion error of the processing end when it moves along the X-axis in the processing three-dimensional coordinate system, it is necessary to first complete the optical path debugging part of the non-contact measurement equipment, that is: set the laser emitter 10 in the positive direction of the X-axis, adjust the position between the laser emitter 10 and the laser reflector 11, and align the optical path of the laser emitter 10 and the laser reflector 11 with the X-axis direction.

[0072] After completing the optical path debugging part of the non-contact measuring equipment, the spatial motion error measurement part begins, that is, driving the processing execution device 1 so that the processing end drives the coordinate probe measuring device 4 and the laser reflector 11 to move along the X-axis, and at the same time turning on the laser emitter 10. The laser emitted by the laser emitter 10 is reflected back to the laser emitter 10 through the laser reflector 11. The laser emitted by the laser emitter 10 and the received laser interfere with each other in the laser emitter 10, and the straightness and linearity of the processing end during the X-axis movement are obtained according to the interference result, that is, the spatial motion errors of the processing end in the X-axis, Y-axis and Z-axis directions in the processing three-dimensional coordinate system when the X-axis moves.

[0073] like Figure 6 As shown in (c), after completing the measurement of the spatial motion error of the processing end along the X-axis, the laser emitter 10 is kept set in the positive direction of the X-axis, and a folding mirror 12 is set in the optical path of the laser emitter 10, so that the laser emitted by the laser emitter 10 along the X-axis direction is folded to the Y-axis direction after passing through the folding mirror 12.

[0074] At this time, the processing end drives the coordinate probe measuring device 4 and the laser reflector 11 to move in the Y-axis direction where the folding mirror 12 is located, so that the laser emitted by the laser emitter 10 along the X-axis direction is folded into the laser reflector 11 after passing through the folding mirror 12. The laser reflector 11 reflects the incident laser, and the reflected laser enters the laser emitter 10 after being folded by the folding mirror 12. The laser emitted by the laser emitter 10 and the received laser interfere with each other in the laser emitter 10, and the orthogonality error of the processing end in the X-axis direction and the Y-axis direction is obtained when the processing end moves in the Y-axis direction. The orthogonality error will cause the movement direction of the processing end of the processing execution device 1 to be distorted, resulting in the processing end of the processing execution device 1 moving along the X-axis direction. The end actuator gradually deviates to the Y-axis direction to generate a spatial motion error, and the error is proportional to the X-axis motion.

[0075] The above three errors are correspondingly superimposed (i.e., the spatial motion error in the X-axis direction when the processing end moves along the Y-axis and X-axis respectively is correspondingly superimposed; the spatial motion error in the Y-axis direction and the orthogonality error when the processing end moves along the Y-axis and X-axis respectively is correspondingly superimposed; the spatial motion error in the Z-axis direction when the processing end moves along the Y-axis and X-axis respectively is correspondingly superimposed), and the spatial motion error distribution of the coordinate probe measuring device 4 can be obtained as shown in FIG. Figure 7 shown. Figure 7 The overall distribution of the spatial motion errors of the coordinate probe measuring device 4 in the X-axis direction, the Y-axis direction and the Z-axis direction are shown respectively, where X and Y represent the X-axis direction and the Y-axis direction in the three-dimensional machining coordinate system respectively, and the color bar is the motion error value in mm.

[0076] S3: The processing end drives the coordinate probe measuring device 4 to contact the optical element 6 point by point along the set measurement trajectory, and records the position coordinates of each contact point; the spatial motion error is compensated to the position coordinates of each contact point, and the new position coordinates of each contact point are obtained, and then the coordinate measurement results of the optical element 6 are obtained.

[0077] Specifically, the processing end drives the coordinate probe measuring device 4 along the Fig.10 The measuring track moves point by point to the top of the optical element 6. At each measuring point on the measuring track, the processing end drives the probe to slowly press down until the coordinate probe measuring device 4 contacts the surface of the optical element 6. At this time, the coordinate probe measuring device 4 sends a stop signal to the processing execution device and records the position coordinates of the current contact point. Figure 8 (a) shows a top view of the measurement trajectory. Figure 8 (b) shows a three-dimensional diagram of the measurement trajectory.

[0078] The spatial motion errors in the X-axis and Y-axis directions corresponding to each contact point are subtracted from the position coordinates of each contact point to complete the compensation of the spatial motion errors of the processing end along the X-axis and Y-axis directions. The spatial motion error in the Z direction is then added to the Z-direction measurement result of each contact point to eliminate the spatial motion error of the processing execution device 1. After compensating the spatial motion error corresponding to each contact point with the position coordinates of each contact point, the new position coordinates of each contact point are obtained, and then the new position coordinates of each contact point are fitted to obtain the coordinate measurement results of the optical element 6.

[0079] like Fig. 9 As shown in the figure , and They represent the spatial motion errors in the X-axis, Y-axis and Z-axis directions when the processing end moves along the X-axis. It can be seen that in the process of the processing end moving along the X-axis, the three spatial motion errors after compensation are significantly reduced compared with those before compensation. Fig.10 As shown in the figure , and They respectively represent the spatial motion errors in the X-axis, Y-axis and Z-axis directions when the processing end moves along the Y-axis. It can be seen that in the process of the processing end moving along the Y-axis, the three spatial motion errors after compensation are significantly reduced compared with those before compensation. It can be seen that the present invention uses the optical interference principle to measure the spatial motion error, so that after the spatial motion error compensation of the processing end, the spatial motion error of the processing end can be effectively converged to the micron level, and the measurement accuracy of the coordinate probe measurement device 4 can reach 0.1μm, and the measurement accuracy is greatly improved.

[0080] S4: Fit the coordinate measurement results with Zernike polynomials, and then extract the defocus from the fitting results; add the defocus to the actual surface morphology to obtain the final surface error distribution.

[0081] During the swing arm measurement process, the processing execution device 1 is in a stationary state except for the processing end and the processing turntable. The introduced spatial motion error can be corrected by the overlapping points, so the measurement accuracy of the swing arm measurement device 3 can reach the sub-micron level. Since the sampling frequency of the swing arm measurement device 3 is high and the data is dense, it can better reflect the real surface error distribution of the optical element 6. However, since the swing arm measurement device 3 uses spherical coordinates to measure the surface accuracy, the defocus in the measurement result can only be removed as a system error, so this technology cannot achieve high-precision curvature radius measurement. The coordinate probe detection data after error compensation can reach micron-level accuracy. Using the Zernike polynomial fitting commonly used in optical detection, the defocus can be extracted from the surface shape. Adding it to the swing arm detection result can obtain the surface error distribution of the optical element 6 with high precision, which is used to guide subsequent processing.

[0082] like Fig.11 As shown in the figure, Power in the figure represents the defocus value. The coordinate measurement results are fitted with Zernike polynomials, and then separated from the fitting results. After the defocus is extracted separately, the distribution of the surface error is highly consistent with the swing arm measurement result, but the data density is low. After adding the defocus to the swing arm measurement result, the final surface error distribution of the optical element 6 can be obtained, and the in-situ measurement is completed, which can be used to guide the subsequent iterative removal.

[0083] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0084] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for high-precision on-site detection of large-aperture optical components in full frequency bands, used in a high-precision on-site detection device for large-aperture optical components in full frequency bands, characterized in that: The in-situ detection device comprises a processing execution device, a quick-change tool station, a swing arm measuring device, a coordinate probe measuring device, a non-contact measuring device and a polishing tool group; wherein the optical element is placed on the processing turntable of the processing execution device; the quick-change tool station is integrated on the processing execution device, and the swing arm measuring device, the coordinate probe measuring device and the polishing tool group are arranged on the quick-change tool station; the processing execution device has a processing end, and the processing end is switchably connected with the swing arm measuring device, the coordinate probe measuring device and the polishing tool group; the non-contact measuring device is installed on the processing execution device, and cooperates with the coordinate probe measuring device to complete the measurement of the position coordinates and spatial motion error of the processing end; The swing arm measuring device comprises an air-floating turntable, a supporting measuring arm and a displacement sensor; wherein the air-floating turntable and the displacement sensor are respectively located at two ends of the supporting measuring arm; the air-floating turntable is tilted, and the axis of the air-floating turntable passes through the best fitting sphere center of the optical element; the air-floating turntable is connected to the processing end, so that the processing end drives the displacement sensor to rotate around the axis of the air-floating turntable through the air-floating turntable and the supporting measuring arm; during the rotation process, the displacement sensor passes through the geometric center of the optical element; The processing end of the processing execution device is switchably connected to the coordinate probe measuring device through a quick change device, so that the processing end drives the end of the coordinate probe measuring device to contact the surface of the optical element; when the end of the coordinate probe measuring device contacts the surface of the optical element, the coordinate probe measuring device sends a stop motion signal to the processing execution device, and the processing execution device records the machine tool motion coordinates of the current contact point through its own numerical control system; The in-situ detection method specifically comprises the following steps: S1: The processing end grabs the quick-change tool station and drives the swing arm measuring device to move on the surface of the optical element; the swing arm measuring device measures the overall offset between the actual curved surface morphology of the optical element and the best fitting sphere of the optical element, thereby obtaining the actual curved surface morphology; S2: The processing end puts the swing arm measuring device back to the quick-change tool station, then grabs the coordinate probe measuring device from the quick-change tool station and drives it to move into the measuring range of the non-contact measuring device; the non-contact measuring device cooperates with the coordinate probe measuring device to complete the measurement of the spatial motion error of the processing end; S3: the processing end drives the coordinate probe measuring device to contact the optical element point by point along a set measurement trajectory, and records the position coordinates of each contact point; the spatial motion error is compensated to the position coordinates of each contact point, and the new position coordinates of each contact point are obtained, thereby obtaining the coordinate measurement result of the optical element; S4: performing Zernike polynomial fitting on the coordinate measurement results, and then extracting the defocus amount from the fitting results; adding the defocus amount to the actual surface morphology to obtain a final surface error distribution.

2. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 1 is characterized in that: The processing execution device is a double-axis gantry machine tool.

3. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 2 is characterized in that: The polishing tool set includes no less than two computer-controlled small grinding head processing tools, and the size of each computer-controlled small grinding head processing tool is different.

4. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 1 is characterized in that: The step S1 specifically includes the following steps: S11: the processing end drives the displacement sensor to rotate around the axis of the air-floating turntable, so that the probe of the displacement sensor sweeps a circular trajectory on the surface of the optical element; the displacement sensor obtains the offset between the actual surface morphology of the optical element and the best fitting sphere of the optical element under the current circular trajectory according to the current circular trajectory; S12: The processing turntable drives the optical element to rotate around the axis of the processing turntable by an angle , and repeating step S11 after the rotation until the optical element rotates one circle, at which time a series of circular tracks and a series of offsets corresponding to the circular tracks are obtained; S13: correcting the overlapping points between a series of circular trajectories to obtain the overall offset, and then adding the overall offset to the best fitting sphere to obtain the actual curved surface morphology.

5. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 1 is characterized in that: In step S2, When the machining end drives the coordinate probe measuring device to move along the X-axis in the machining three-dimensional coordinate system of the machining execution device, the spatial motion errors of the coordinate probe measuring device in the X-axis, Y-axis and Z-axis directions in the machining three-dimensional coordinate system are measured by the non-contact measuring device; When the processing end drives the coordinate probe measuring device to move along the Y-axis in the processing three-dimensional coordinate system of the processing execution device, the spatial motion errors of the coordinate probe measuring device in the X-axis, Y-axis and Z-axis directions in the processing three-dimensional coordinate system are measured by the non-contact measuring equipment.

6. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 5, characterized in that: The center point of the processing three-dimensional coordinate system in step S2 is the surface center of the optical element.

7. The method for high-precision in-situ detection of large-aperture optical components in all frequency bands according to claim 6, characterized in that: In step S3, the processing end drives the coordinate probe measuring device to move point by point along the measuring trajectory to the top of the optical element; at each measuring point on the measuring trajectory, the processing end drives the coordinate probe measuring device to press down until the coordinate probe measuring device contacts the surface of the optical element, at which time the coordinate probe measuring device sends a stop motion signal to the processing execution device and records the position coordinates of the current contact point.

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