A device and method for in-situ detection of surface profile processing of a meter-scale element

Abstract

This invention discloses an in-situ detection device and method for meter-level component surface shape processing, belonging to the field of optical precision inspection technology. Its purpose is to solve the technical problem of insufficient in-situ detection capability for meter-level component surface shapes, which affects the high-precision, high-efficiency, and non-destructive processing of core components in large optical systems. The detection optical path is as follows: A laser beam generated by a laser sequentially passes through a beam isolator, converging lens A, filter A, collimating lens A, beam splitter A, converging lens B, beam splitter B, and collimating lens B before being incident on the meter-level component under test and reflected. The reflected laser beam passes through collimating lens B and then enters beam splitter B, splitting into two laser beams. One laser beam passes through filter B and enters a measuring CCD camera. The light spot recorded by the measuring CCD camera is input into a computer for reconstructing the surface shape of the meter-level component under test. The other laser beam sequentially passes through converging lens B, beam splitter A, and converging lens C before being focused onto a screen. The CCD camera is monitored to collect and calculate the offset between the focal point and the center of the screen.

Description

Technical Field

[0001] This invention belongs to the field of optical precision testing technology, and relates to the surface shape measurement of optical elements with apertures of meters and above, and particularly to an in-situ testing device and method for surface shape processing of meter-level elements. Background Technology

[0002] In large-scale optical engineering projects such as space optical systems and hard X-ray free-electron laser devices, the aperture of optical systems has evolved from the traditional 300mm-500mm to the current level of over 3m. The increase in component aperture has placed more stringent requirements on the processing and testing of large-aperture optical components in optical systems.

[0003] Traditional detection methods involve transporting large-aperture optical components to an interferometer for testing. For example, patent application number 202410786005.5 discloses a point diffraction interference surface shape detection device and method, which includes: an optical transmission module configured as one optical path adjustable optical path and another optical path fixed optical path; an ideal wavefront generation unit for receiving two beams of light output from the optical transmission module and generating two standard wavefronts; and a phase shifter for compensating for optical path difference, a beam splitter, and a mask placed on a precision adjustment stage, all located on the optical path adjustable optical path; the two standard wavefronts are incident on the surface of the spherical mirror under test through the beam splitter, reflected by the surface of the spherical mirror under test, and then incident again on the beam splitter. After being reflected by the beam splitter, the beams converge onto the mask. By adjusting the precision adjustment stage, both standard wavefronts pass through the transparent area of ​​the mask, overlapping and interfering with each other. By moving the phase shifter, multiple interferograms are obtained, thus obtaining the system error Ts. By adjusting the precision adjustment stage, one of the two standard wavefronts passes through the transparent area of ​​the mask, while the other passes through the center of the filter aperture of the mask. By moving the phase shifter, multiple interferograms are obtained, thus obtaining the surface shape distribution Tc. By calculating the interferometer system error Ts and the surface shape distribution Tc, the surface shape distribution T of the spherical mirror under test is obtained.

[0004] Similar to the aforementioned patent applications, most optical component inspection methods fall under the category of offline inspection, which suffers from several problems: 1) Traditional offline inspection cannot provide real-time closed-loop feedback: This leads to repeated disassembly and assembly of components during the manufacturing process due to inspection requirements, resulting in the loss of processing references and difficulty in dynamically correcting processing parameters, thus failing to achieve closed-loop control of "processing-inspection-processing compensation"; 2) Traditional offline inspection methods increase the risk of component damage: From initial molding to final finished component formation, surface shape indicators need to be repeatedly inspected. Each inspection requires transporting optical components weighing hundreds of kilograms from the machine tool to the interferometer. The transportation and debugging processes mean that each measurement takes at least a week, significantly increasing the risk of component damage; 3) The maximum aperture that the interferometer can directly measure is 800mm. Other methods, such as the splicing method and the Richter-Connaught method, cannot meet the measurement accuracy requirements of the manufacturing process. Therefore, it is necessary to achieve in-situ inspection of optical components.

[0005] Patent application number 202510066424.6 discloses an in-situ detection device and method for the surface shape of an optomechanical component, which includes a laser, a beam isolator, a beam splitter, a collimating lens A, an optomechanical component under test, a perforated screen, a collimating lens B, a phase plate, a CCD camera, and a computer system. The laser light generated by the laser passes sequentially through the beam isolator, the beam splitter, and the collimating lens A before being incident on the optomechanical component under test and being reflected. The reflected light from the optomechanical component under test passes through the collimating lens A before being incident on the beam splitter and being reflected. The reflected light from the beam splitter passes through the perforated screen, the collimating lens B, and the phase plate before being incident on the CCD camera. The CCD camera is connected to the computer system, and the light spot image recorded by the CCD camera is input into the computer system for in-situ surface shape detection. It modulates the measurement light field using a phase plate to obtain the diffraction spot information of the optomechanical component under test with strong phase modulation, and then uses a phase reconstruction algorithm based on square diffraction iteration to realize the surface shape reconstruction and in-situ detection of the optomechanical component.

[0006] While the aforementioned invention patent achieves in-situ detection of components, the aperture of the detection component is relatively small (the aperture of the optomechanical assembly under test in the experimental example is 400mm). The capability for in-situ detection of the surface shape of components with apertures larger than meters remains lacking, severely impacting the high-precision, high-efficiency, and non-destructive processing of core components in large optical systems. Therefore, there is an urgent need for a device for in-situ detection of component surface shape distortion to meet the in-situ detection requirements for the surface shape processing of optical components with apertures larger than meters. Summary of the Invention

[0007] The purpose of this invention is to address the technical problem that the existing technology lacks the ability to detect the surface shape of components with apertures larger than meters, which affects the high-precision, high-efficiency, and non-destructive processing of core components of large optical systems. This invention provides an in-situ detection device and method for the surface shape processing of meter-scale components.

[0008] To achieve the above objectives, the present invention specifically adopts the following technical solution: A meter-scale component surface shape processing in-situ inspection device includes a measurement module, a meter-scale component under test, a computer, and an attitude adjustment mechanism. The measurement module includes a laser, a beam isolator, a converging lens A, a filter aperture A, a collimating lens A, a beam splitter A, a converging lens B, a beam splitter B, a collimating lens B, a filter aperture B, a measuring CCD camera, a converging lens C, a screen, and a monitoring CCD camera. The measurement module is mounted on the attitude adjustment mechanism, and the measuring CCD camera is connected to the computer. The laser beam generated by the laser passes sequentially through a beam isolator, converging lens A, filter aperture A, collimating lens A, beam splitter A, converging lens B, beam splitter B, and collimating lens B before being incident on the meter-scale test element and reflected. The reflected laser beam passes through collimating lens B and then enters beam splitter B, where it is split into two laser beams. One laser beam passes through filter aperture B and enters the measuring CCD camera. The light spot recorded by the measuring CCD camera is input into the computer. The other laser beam passes sequentially through converging lens B, beam splitter A, and converging lens C before being focused onto the screen. The monitoring CCD camera collects and calculates the offset between the focal point and the center of the screen.

[0009] Furthermore, the laser output by the laser has a wavelength of 632.8 nm and a coherence length greater than 3 m.

[0010] Furthermore, the beam splitting ratio of beam splitter A is 2:1, and the beam splitting ratio of beam splitter B is 1:1.

[0011] Furthermore, the laser light incident from collimating lens B onto the meter-scale test element is parallel light, and the incident direction of this parallel light is perpendicular to the meter-scale test element.

[0012] Furthermore, the F-number of collimating lens B is between 6 and 15.

[0013] Furthermore, the attitude adjustment mechanism includes a scanning translation module, and the measurement module is mounted on the scanning translation module; the scanning translation module performs two-dimensional scanning of the meter-level component under test.

[0014] Furthermore, when performing two-dimensional scanning on meter-scale components under test, the scanning overlap rate is greater than 50%, and the scanning area completely covers the meter-scale components under test; A series of diffraction spot arrays with overlapping regions were acquired by a measuring CCD camera. The diffraction spot array was processed by a stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element.

[0015] Furthermore, the attitude adjustment mechanism also includes a pitch and tilt adjustment stage, on which the scanning translation module is mounted; the pitch and tilt adjustment stage has a two-dimensional angle adjustment range of not less than ±2° and an adjustment sensitivity of less than 5″; the scanning translation module has a translation range of more than 1m and a translation accuracy of more than 50μm.

[0016] A method for in-situ inspection of the surface shape of meter-level components includes the aforementioned in-situ inspection device for the surface shape of meter-level components. The specific steps for using the in-situ inspection device to inspect the surface shape of a meter-level component under test are as follows: Step 1: The laser generated by the laser passes sequentially through a beam isolator, converging lens A, filter A, collimating lens A, beam splitter A, converging lens B, beam splitter B, and collimating lens B before being incident on the meter-scale test element and reflected. The reflected laser passes through collimating lens B, beam splitter B, and filter B before being incident on the measuring CCD camera. The light spot recorded by the measuring CCD camera is input into the computer to reconstruct the surface shape of the meter-scale test element. Step 2: Adjust the orientation of the meter-level component surface shape processing in-situ detection device so that the measuring beam is perpendicular to the meter-level component under test; Step 3: The measurement module performs a two-dimensional scan of the meter-scale test element. Each scan is accompanied by a diffraction spot captured by the measurement CCD camera. The diffraction spot array is processed using a stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element.

[0017] Furthermore, in step 2, when adjusting the attitude, the adjustment steps are as follows: Step 2-1: The laser generated by the laser passes sequentially through a beam isolator, converging lens A, filter aperture A, collimating lens A, beam splitter A, converging lens B, beam splitter B, and collimating lens B before being incident on the meter-scale test element and being reflected. The reflected laser passes through collimating lens B, beam splitter B, converging lens B, beam splitter A, and converging lens C before being focused onto the screen. The monitoring CCD camera collects and calculates the offset between the focal point and the center of the screen. Step 2-2: The computer adjusts the attitude of the measurement module based on the offset and direction; Step 2-3: Repeat steps 2-1 and 2-2 until the offset is less than 1 pixel.

[0018] The beneficial effects of this invention are as follows: In this invention, a precise image matching method is used to obtain the deviation of the element's perpendicularity to the measurement beam and feedback is used to achieve closed-loop control of the pose. A two-dimensional translational mechanical bearing measurement module is used for scanning to obtain the modulation information of the light field in different regions of the meter-scale optical element under test. Then, a layered coherent diffraction algorithm is used to reconstruct the surface shape of the element. Compared with other interferometric methods, the detection method of this application has advantages such as high measurement accuracy, large measurement aperture, no need for a reference plane, good vibration resistance, and strong resistance to environmental interference. It is suitable for in-situ measurement and has great application prospects to meet the in-situ detection needs of surface shape processing of optical elements with apertures of meter-scale and above. Attached Figure Description

[0019] Figure 1 This is the optical path diagram of the measurement module in this invention; Figure 2 This is a schematic diagram of the structure of the measurement module, the meter-level measured element, and the attitude adjustment mechanism in this invention; Figure 3 This is a schematic diagram of the diffraction spot array acquired by the CCD camera in this invention; Figure 4 This is a schematic diagram of the surface shape distribution of the large-diameter test element in the initial processing stage of this invention; The attached figures are labeled as follows: 101-Laser, 102-Beam isolator, 103-Converging lens A, 104-Filter aperture A, 105-Collimating lens A, 106-Beam splitter A, 107-Converging lens B, 108-Beam splitter B, 109-Collimating lens B, 110-Filter aperture B, 111-Measuring CCD camera, 112-Converging lens C, 113-Screen, 114-Monitoring CCD camera, 115-Scanning translation module, 116-Pitch and tilt adjustment stage, 117-Meter-level test element, 118-Computer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, but not all embodiments.

[0021] Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Explanation of technical terms: Coherence length is an important physical quantity for measuring the temporal coherence of a light source. It defines the maximum distance at which a light wave can maintain phase consistency in the direction of propagation, or the maximum optical path difference allowed in an interference experiment.

[0023] F-number is a core parameter used in optics and photography to represent aperture size. It is also called aperture value or focal ratio. The smaller the number, the larger the aperture.

[0024] A pixel is the smallest independent element that makes up a screen image.

[0025] Example 1 This embodiment provides an in-situ detection device for the surface shape processing of meter-level components, used for in-situ detection of the surface shape distribution of meter-level components. For example... Figure 1 , Figure 2 As shown, it includes: a measurement module, a meter-scale measured element 117, a computer 118, and an attitude adjustment mechanism.

[0026] The measurement module is used to perform in-situ measurements of the surface distribution of the meter-scale test element 117.

[0027] Computer 118 is used to receive the light spot recorded by the measurement module and reconstruct the surface shape based on the light spot.

[0028] The attitude adjustment mechanism is used to adjust the attitude of the measurement module so that it can fully cover the meter-level test element 117.

[0029] The measurement module includes a laser 101, a beam isolator 102, a converging lens A103, a filter aperture A104, a collimating lens A105, a beam splitter A106, a converging lens B107, a beam splitter B108, a collimating lens B109, a filter aperture B110, a measuring CCD camera 111, a converging lens C112, a light screen 113, and a monitoring CCD camera 114. The measurement module is mounted on the attitude adjustment mechanism, and the measuring CCD camera 111 is connected to the computer 118.

[0030] The laser output by laser 101 has a wavelength of 632.8 nm and a coherence length greater than 3 m.

[0031] The filter aperture A104 is located at the focal point of the converging lens A103 and the collimating lens A105, and the converging lens A103 and the collimating lens A105 are confocal; similarly, the converging lens B107 and the collimating lens B109 are placed confocally.

[0032] The beam splitter A106 has a beam splitting ratio of 2:1, and the beam splitter B108 has a beam splitting ratio of 1:1.

[0033] The collimating lens B109 has a diameter of 120 mm and its transmitted wavefront is no greater than λ / 6, where λ = 632.8 nm. The laser light incident from the collimating lens B109 onto the meter-scale test element 117 is parallel light, and the incident direction of this parallel light is perpendicular to the meter-scale test element 117.

[0034] The F-number of the collimating lens B109 is between 6 and 15.

[0035] The monitoring CCD114 can clearly capture the image of the light spot on the screen 113; the screen 113 is located at the focal plane of the converging lens C112, and the screen 113 has a crosshair.

[0036] The attitude adjustment mechanism includes a scanning translation module 115 and a pitch and tilt adjustment stage 116. The measurement module is mounted on the scanning translation module 115, which performs a two-dimensional scan of the meter-scale measured element 117. The scanning translation module 115 is mounted on the pitch and tilt adjustment stage 116, which is used to adjust the pitch angle of the scanning translation module 115 so that the parallel light emitted from the collimating lens B109 is perpendicular to the meter-scale measured element 117. The pitch and tilt adjustment stage 116 has a two-dimensional angle adjustment range of not less than ±2° and an adjustment sensitivity of less than 5″; the scanning translation module 115 has a translation range of more than 1m and a translation accuracy of more than 50μm. When performing two-dimensional scanning on the meter-scale test element 117, the scanning overlap rate is greater than 50%, and the scanning area completely covers the meter-scale test element 117; the measuring CCD camera 111 acquires a series of diffraction spot arrays with overlapping areas, and the diffraction spot array is processed using the stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element 117.

[0037] The detection optical path is as follows: The laser generated by laser 101 passes sequentially through beam isolator 102, converging lens A103, filter aperture A104, collimating lens A105, beam splitter A106, converging lens B107, beam splitter B108, and collimating lens B109 before being incident on the meter-scale test element 117 and reflected. The reflected laser passes through collimating lens B109 and then enters beam splitter B108, where it is split into two laser beams. One laser beam passes through filter aperture B110 and then enters the measuring CCD camera 111. The measuring CCD camera 111 records the light spot (e.g., ...). Figure 3 (As shown) The data is input into computer 118, which reconstructs the surface distribution of the meter-scale measured element 117, as shown. Figure 4 As shown; another laser beam passes through converging lens B107, beam splitter A106, and converging lens C112 in sequence and is focused onto screen 113. The monitoring CCD camera 114 collects and calculates the offset between the focal point and the center of screen 113.

[0038] Example 2 This embodiment provides an in-situ detection method for the surface shape processing of meter-level components, used for in-situ detection of the surface shape distribution of meter-level components. When using the in-situ detection device for the surface shape processing of meter-level components from Embodiment 1, the specific detection steps are as follows: Step 1: The laser generated by laser 101 passes sequentially through beam isolator 102, converging lens A103, filter aperture A104, collimating lens A105, beam splitter A106, converging lens B107, beam splitter B108, and collimating lens B109 before being incident on the meter-scale test element 117 and reflected. The reflected laser passes through collimating lens B109, beam splitter B108, and filter aperture B110 before being incident on the measuring CCD camera 111. The light spot recorded by the measuring CCD camera 111 is input into computer 118 to reconstruct the surface shape of the meter-scale test element 117. Step 2: Adjust the orientation of the meter-level component surface shape processing in-situ detection device so that the measuring beam is perpendicular to the meter-level component under test 117; Step 3: The measurement module performs a two-dimensional scan of the meter-scale test element 117. Each scan is performed by the measurement CCD camera 111, which acquires a diffraction spot. The diffraction spot array is processed using the stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element 117.

[0039] Step 2, when adjusting the attitude, involves the following steps: Step 2-1: The laser generated by laser 101 passes sequentially through beam isolator 102, converging lens A103, filter aperture A104, collimating lens A105, beam splitter A106, converging lens B107, beam splitter B108, and collimating lens B109 before being incident on the meter-scale test element 117 and being reflected. The reflected laser passes through collimating lens B109, beam splitter B108, converging lens B107, beam splitter A106, and converging lens C112 before being focused onto the screen 113. The monitoring CCD camera 114 collects and calculates the offset between the focal point and the center of the screen 113. The focus is calculated using barycentric coordinates. For each connected region, its barycentric coordinates are... for: ; ; in, The zeroth moment (i.e., the area of ​​the region, calculated in pixels) is the total number of pixels in the region (i.e., the area). , Both represent first-order moments. It is the sum of the x-coordinates of all pixels. It is the sum of the y-coordinates of all pixels.

[0040] Step 2-2: The computer 118 feeds back the offset and direction to the pitch and tilt adjustment platform 116 to adjust the attitude of the measurement module. Step 2-3: Repeat steps 2-1 and 2-2 until the offset between the focus of the monitoring CCD camera 114 and the screen 113 is less than 1 pixel.

Claims

1. A meter-level component surface shape processing in-situ detection device, characterized in that: The device includes a measurement module, a meter-scale device under test (117), a computer (118), and an attitude adjustment mechanism. The measurement module includes a laser (101), a beam isolator (102), a converging lens A (103), a filter aperture A (104), a collimating lens A (105), a beam splitter A (106), a converging lens B (107), a beam splitter B (108), a collimating lens B (109), a filter aperture B (110), a measurement CCD camera (111), a converging lens C (112), a light screen (113), and a monitoring CCD camera (114). The measurement module is mounted on the attitude adjustment mechanism, and the measurement CCD camera (111) is connected to the computer (118). The laser generated by the laser (101) passes through the beam isolator (102), converging lens A (103), filter aperture A (104), collimating lens A (105), beam splitter A (106), converging lens B (107), beam splitter B (108), and collimating lens B (109) in sequence before being incident on the meter-scale test element (117) and being reflected. The reflected laser passes through collimating lens B (109) and then enters beam splitter B (108) and is split into two laser beams. One laser beam passes through filter aperture B (110) and then enters the measuring CCD camera (111). The light spot recorded by the measuring CCD camera (111) is input into the computer (118). The other laser beam passes through the converging lens B (107), beam splitter A (106), and converging lens C (112) in sequence before being focused on the screen (113). The monitoring CCD camera (114) collects and calculates the offset between the focal point and the center of the screen (113).

2. The meter-level component surface shape processing in-situ detection device as described in claim 1, characterized in that: The laser (101) outputs a laser with a wavelength of 632.8 nm and a coherence length greater than 3 m.

3. The meter-level component surface shape processing in-situ detection device as described in claim 1, characterized in that: The beam splitting ratio of beam splitter A (106) is 2:1, and the beam splitting ratio of beam splitter B (108) is 1:

1.

4. The meter-level component surface shape processing in-situ detection device as described in claim 1, characterized in that: The laser beam incident from collimating lens B (109) onto the meter-scale test element (117) is parallel light, and the incident direction of the parallel light is perpendicular to the meter-scale test element (117).

5. A device for in-situ detection of surface profile machining of a rice-size element according to claim 1, characterized in that: The F-number of collimating lens B (109) is between 6 and 15.

6. The meter-level component surface shape processing in-situ detection device as described in claim 1, characterized in that: The attitude adjustment mechanism includes a scanning translation module (115), and the measurement module is mounted on the scanning translation module (115); the meter-level test element (117) is scanned in two dimensions by the scanning translation module (115).

7. The meter-level component surface shape processing in-situ detection device as described in claim 6, characterized in that: When performing a two-dimensional scan on the meter-scale device under test (117), the scan overlap rate is greater than 50%, and the scan area completely covers the meter-scale device under test (117). The measuring CCD camera (111) acquires a series of diffraction spot arrays with overlapping regions. The diffraction spot array is processed by the stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element (117).

8. A device for in-situ detection of surface profile machining of a rice-sized element as claimed in claim 6, characterized in that: The attitude adjustment mechanism also includes a pitch tilt adjustment stage (116), and a scanning translation module (115) is installed on the pitch tilt adjustment stage (116); the two-dimensional angle adjustment range of the pitch tilt adjustment stage (116) is not less than ±2° and the adjustment sensitivity is less than 5″; the translation range of the scanning translation module (115) is greater than 1m and the translation accuracy is greater than 50μm.

9. A method for in-situ detection of face shape processing of a meter-scale element, characterized in that, The device includes the meter-scale component surface shape processing in-situ inspection device according to any one of claims 1-8; when using the meter-scale component surface shape processing in-situ inspection device to perform surface shape inspection on the meter-scale component under test (117), the specific steps are as follows: Step 1: The laser generated by the laser (101) passes sequentially through the beam isolator (102), converging lens A (103), filter aperture A (104), collimating lens A (105), beam splitter A (106), converging lens B (107), beam splitter B (108), and collimating lens B (109) before being incident on the meter-scale test element (117) and being reflected. The reflected laser passes through collimating lens B (109), beam splitter B (108), and filter aperture B (110) before being incident on the measuring CCD camera (111). The light spot recorded by the measuring CCD camera (111) is input into the computer (118) to reconstruct the surface shape of the meter-scale test element (117). Step 2: Adjust the orientation of the meter-level component surface shape processing in-situ detection device so that the measuring beam is perpendicular to the meter-level component under test (117). Step 3: The measurement module performs a two-dimensional scan of the meter-scale test element (117). Each scan is performed by the measurement CCD camera (111) to acquire a diffraction spot. The diffraction spot array is processed by the stacked coherent diffraction method to reconstruct the surface shape of the meter-scale test element (117).

10. The method for in-situ detection of meter-level component surface shape processing as described in claim 9, characterized in that, Step 2, when adjusting the attitude, involves the following steps: Step 2-1: The laser generated by the laser (101) passes through the beam isolator (102), converging lens A (103), filter aperture A (104), collimating lens A (105), beam splitter A (106), converging lens B (107), beam splitter B (108), and collimating lens B (109) in sequence and is then incident on the meter-scale test element (117) and reflected. The reflected laser passes through collimating lens B (109), beam splitter B (108), converging lens B (107), beam splitter A (106), and converging lens C (112) and is then focused on the screen (113). The monitoring CCD camera (114) collects and calculates the offset between the focal point and the center of the screen (113). Step 2-2: The computer (118) adjusts the attitude of the measurement module according to the offset and direction; Step 2-3: Repeat steps 2-1 and 2-2 until the offset is less than 1 pixel.

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