Method and system for selective elimination of internal residual stress of an optical element

Abstract

The application discloses a method and system for selectively eliminating internal residual stress of an optical element. The method comprises the following steps: firstly, scanning the optical element to be processed by using a three-dimensional stress measuring device to obtain the real three-dimensional residual stress distribution data inside the optical element; then, identifying a target point based on the obtained three-dimensional residual stress distribution data and calculating the corresponding three-dimensional coordinates; finally, controlling a laser beam and focusing the laser beam on the three-dimensional coordinates of the target point inside the optical element to be processed by using a high numerical aperture objective lens to irradiate, and realizing stress relaxation by using local thermal effect. The system integrates the three-dimensional stress measuring device and the focused laser irradiation device, and ensures the uniformity of the coordinates by setting a shared optical path. The application realizes the precise minimally invasive processing of "what you see is what you treat", can selectively eliminate the residual stress points at any depth inside the optical element, and has the advantages of real processing basis, direct and in-depth action, high spatial precision and closed-loop feedback.

Description

Technical Field

[0001] This application belongs to the field of precision optical manufacturing and laser processing technology, specifically relating to a method and system for selectively eliminating residual stress inside optical components. Background Technology

[0002] In high-performance optical systems (such as extreme ultraviolet lithography machines, gravitational wave detectors, and inertial confinement fusion laser devices), the performance of optical components directly determines the ultimate limits of the system. Residual stress is introduced into these optical components during manufacturing processes such as melting, forming, cutting, grinding, and polishing. The presence of residual stress leads to optical surface distortion, induces stress birefringence, and significantly reduces the laser damage threshold of the optical components, thus becoming a key bottleneck restricting the improvement of system performance.

[0003] Current mainstream technologies for eliminating residual stress in optical components mainly include: (1) Overall heat treatment annealing: The optical element is placed in an annealing furnace and heated for a long time. Although this method can reduce the average stress, the process is time-consuming and energy-intensive, and it is easy to cause uncontrollable deformation of the optical element as a whole. It is not possible to correct local stress concentration areas, and it is not suitable for integrated or surface-shape-required optical elements.

[0004] (2) Laser shock strengthening or smoothing: Laser-induced plasma shock waves are used to improve the surface stress of optical components. However, its depth of action is limited to the micron-level surface layer, and it is powerless to address the residual stress inside the optical components. Furthermore, high-energy shocks may introduce new micro-damage.

[0005] (3) Simulation-based partitioned laser processing: As shown in Chinese Patent Publication No. CN115874120A, this method first predicts the stress distribution through finite element simulation, and then uses a defocused laser to perform partitioned scanning on the surface of the optical element. This method has fundamental defects: First, the simulated stress distribution on which it relies will inevitably deviate from the actual stress state of the optical element, resulting in inaccurate processing basis; second, the defocused laser processing method it uses deposits energy on the surface and indirectly affects the interior through heat conduction, resulting in shallow depth of action and low precision, making it impossible to intervene in specific points inside the optical element, and is essentially still a surface optimization method.

[0006] Therefore, existing technologies lack an effective means to eliminate residual stress inside optical components in situ, directly, and precisely. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of existing technologies that rely on simulation, have superficial effects, and cannot accurately intervene in the internal stress of optical components. It provides a method and system for selectively eliminating residual stress inside optical components based on real measurement, focusing on the internal structure, and closed-loop control, achieving precise minimally invasive processing that allows for "what you see is what you treat".

[0008] To achieve the above objectives, the core of this invention lies in constructing a closed-loop technical system of "high-precision three-dimensional diagnosis - internal focused targeted therapy - real-time feedback verification". Its essential characteristics, distinguishing it from existing technologies, are: abandoning the predictive nature of simulation and employing direct three-dimensional non-destructive measurement of physical optical components as the basis for action; and abandoning defocused surface treatment and employing direct energy deposition by precisely focusing a laser on internal stress points as the means of action.

[0009] In a first aspect, the present invention provides a method for selectively eliminating residual stress inside an optical element, the method comprising the following steps: S100, Three-dimensional stress mapping: Based on the three-dimensional stress distribution measurement device, the optical element to be processed is scanned to obtain the three-dimensional distribution data of the residual stress inside the optical element to be processed; Specifically, phase-sensitive optical coherence tomography or photoelastic scanning system is used to perform three-dimensional spatial scanning of the optical element to be processed, and directly acquire and reconstruct the full three-dimensional stress tensor distribution data that reflects the true stress state inside the optical element to be processed.

[0010] S200, Target Location: Based on the acquired three-dimensional distribution data of residual stress, identify and determine the three-dimensional spatial coordinates of at least one target point inside the optical element to be processed. Specifically, based on the three-dimensional stress measurement data of the optical element to be processed obtained in step S100, regions where the stress amplitude or gradient exceeds a preset threshold are identified as target points, and the three-dimensional spatial coordinates of each target point inside the optical element to be processed are accurately calculated.

[0011] S300, Internal Focused Laser Irradiation: Based on the three-dimensional spatial coordinates, the laser beam is controlled to pass through a high numerical aperture focusing system, and its focus is guided and positioned at the corresponding target point inside the optical element to be processed for irradiation, so as to eliminate the residual stress of the target point. Specifically, based on the three-dimensional spatial coordinates calculated in step S200, a continuous or long-pulse laser beam is controlled and precisely focused onto the three-dimensional coordinate position of the target point inside the optical element to be processed through a high numerical aperture objective lens. Then, by adjusting the laser power, pulse width, and focal dwell time, a controlled local temperature rise is generated in the target area. This temperature rise should reach or slightly exceed the strain point of the material of the optical element to be processed, but be far below its softening point or melting point, thereby inducing viscous flow or atomic rearrangement of the local material of the optical element to be processed, releasing its elastic strain energy, and realizing the relaxation of residual stress.

[0012] S400, On-orbit monitoring and closed-loop feedback: During or between steps S300, the stress state of the target point is measured again, and the laser irradiation parameters are dynamically adjusted or it is decided whether to perform supplementary irradiation based on the results of the remeasurement.

[0013] Specifically, during or between internally focused laser irradiation sessions, a diagnostic module integrated into the same system monitors the stress relaxation process of the target area in real time or near real time. Based on the monitoring results, laser parameters are dynamically adjusted until the stress at the target point drops below the target threshold. By comparing the monitoring data with the target threshold (e.g., stress dropping below a safe threshold), a closed-loop feedback mechanism is established. Dynamically adjusting laser parameters (e.g., turning off the laser or moving to a new position) ensures optimal treatment results without causing secondary damage.

[0014] Secondly, the present invention also provides a selective elimination system for implementing the above-described method, comprising: A three-dimensional stress measurement device is used to scan the optical element to be processed and output the three-dimensional distribution data of residual stress inside the optical element to be processed. The measurement device is a phase-sensitive optical coherence tomography system or a photoelastic scanning system. A focused laser irradiation device includes a laser source and a focusing optical path, used to generate a laser beam and position the focal point of the laser beam at a three-dimensional spatial point inside the optical element to be processed. The laser source is a continuous wave or long pulse laser, and its output wavelength corresponds to the absorption band of the material of the optical element to be processed. The optical paths of the focused laser irradiation device and the three-dimensional stress measurement device are combined by a beam splitter and finally output to the optical element to be processed through the same high numerical aperture objective lens. The control unit, which is communicatively connected to the three-dimensional stress measurement device and the focused laser irradiation device, is configured to: identify the target point and generate the corresponding three-dimensional coordinates based on the residual stress three-dimensional distribution data output by the three-dimensional stress measurement device; and control the focused laser irradiation device to move the laser beam focus to the three-dimensional coordinates of the target point and perform irradiation.

[0015] Preferably, it also includes a multi-axis precision motion platform for carrying the optical element to be processed. The control unit coordinates and controls the multi-axis precision motion platform and the focusing optical path of the focused laser irradiation device to realize the positioning of the focal point of the laser beam in the three-dimensional space inside the optical element to be processed.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: (1) The present invention uses a three-dimensional stress measurement device to perform three-dimensional non-destructive measurement of the optical element to be processed, which eliminates the error between the simulation model and the actual state, making the subsequent laser elimination target clear and reliable, and ensuring the accuracy of the processing from the source; at the same time, it completely changes the rough mode of the overall processing, only intervening in the harmful stress concentration points, preserving the original performance of the optical element substrate to the greatest extent, and avoiding the deformation that may be caused by the overall heat treatment.

[0017] (2) By precisely focusing the laser on the target point inside the optical element to be treated, the energy is directly deposited in the stress concentration core area of ​​the optical element to be treated, realizing the paradigm shift from "indirect influence of surface heat conduction" to "direct energy deposition-driven relaxation", thereby realizing direct and active intervention on the stress at any depth inside the optical element to be treated.

[0018] (3) The present invention combines direct measurement with micron-level resolution and high-precision positioning with common optical path, which can identify and process internal stress defects of optical elements with a scale of tens of microns or less, and the spatial control accuracy is improved by more than an order of magnitude compared with the defocus surface treatment method.

[0019] (4) The present invention adopts the full-process integration and feedback of "measurement-positioning-focusing processing-monitoring" to form an adaptive intelligent system, which significantly improves the consistency, controllability and yield of the process, and is especially suitable for the performance repair and improvement of high-value and difficult-to-replace optical components. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for selectively eliminating residual stress inside an optical element according to the present invention; Figure 2 This is a structural block diagram of a selective residual stress elimination system inside an optical element according to the present invention; Figure 3 This is a schematic diagram of the three-dimensional stress distribution inside an optical element in this invention, wherein the highlighted areas are the target points corresponding to the identified stress concentration areas; Figure 4 This is a schematic diagram of the focused laser beam irradiating the stress concentration point in this invention; Figure 5 This is a schematic diagram of the internal stress distribution of the optical element before and after irradiation treatment in Embodiment 1 of the present invention, wherein, Figure 5 Figure a shows a schematic diagram of the internal stress distribution of the optical element before irradiation treatment. Figure 5 b shows a schematic diagram of the internal stress distribution of the optical element after irradiation treatment.

[0022] In the diagram: 1. Laser source, 2. Second focusing lens, 3. Third reflecting mirror, 4. Fourth reflecting mirror, 5. Stress detection light source, 6. Beam expander collimator, 7. First reflecting mirror, 8. First polarizer, 9. Multi-axis precision motion platform, 10. Beam collector, 11. Beam splitter, 12. Quarter-wave plate, 13. Second reflecting mirror, 14. Second polarizer, 15. First focusing lens, 16. Acquisition camera, 17. Controller, 18. Processor. Detailed Implementation

[0023] To make the objectives, technical solutions, and technical effects of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings, multiple embodiments, and comparative examples. In the following description, the same components are referred to by the same reference numerals.

[0024] Figure 1 A flowchart of a method for selectively eliminating residual stress inside an optical element according to the present invention is shown; Figure 2 A structural block diagram of a selective residual stress elimination system inside an optical element according to the present invention is shown. Wherein, Figure 1 The 9' in the figure represents the multi-axis precision motion platform after it has been moved.

[0025] The general configuration of the selective elimination system in this invention is as follows: The selective stress elimination system includes a three-dimensional stress measurement device, a focused laser irradiation device, a control unit, a multi-axis precision motion platform 9, and a beam collector 10, wherein: The three-dimensional stress measurement device includes a stress detection light source 5, a beam splitter 11, a first auxiliary optical path, a second auxiliary optical path, and a third auxiliary optical path. The first auxiliary optical path is located between the stress detection light source 5 and the beam splitter 11 and includes a beam expander collimator 6, a first reflector 7, and a first polarizer 8 connected in sequence. The second auxiliary optical path includes a second polarizer 14, a first focusing lens 15, and a data acquisition camera 16 connected in sequence. The second auxiliary optical path is connected to the beam splitter 11 through the second polarizer 14 and to the control unit through the data acquisition camera 16. The third auxiliary optical path includes a quarter-wave plate 12 and a second reflector 13 connected in sequence. The third auxiliary optical path is connected to the beam splitter 11 through the second reflector. The three-dimensional stress measurement device scans the optical components to be processed on the multi-axis precision motion platform 9 through the stress detection light source 5, the beam splitter 11, the first auxiliary optical path, the second auxiliary optical path, and the third auxiliary optical path. Among them, the stress detection light source 5 is a broadband light source with a center wavelength of 850nm, a spectral width of 200nm, and a theoretical axial resolution of 2.5μm; the beam splitter 11 and the optical elements in the first, second, and third auxiliary optical paths are all applicable to wavelengths greater than or equal to 700-900nm; the acquisition camera 16 is a scientific research-grade short-wave infrared camera with a spectral range of 400nm-1700nm, a frame rate and resolution of 2560x2048 at 165fps; The focused laser irradiation device includes a laser source 1 and a focusing optical path. The laser source 1 is a carbon dioxide laser with a wavelength of 10.6 μm, a maximum power of 60 W, and a pulse frequency of 200 kHz. The focusing optical path includes a second focusing lens 2, a third reflecting mirror 3, and a fourth reflecting mirror 4 connected in sequence. The second focusing lens 2 is a high numerical aperture focusing lens, which can focus the output spot of the laser source 1 to a diameter of 2 μm. The third reflecting mirror 3 and the fourth reflecting mirror 4 both adopt multilayer dielectric anti-reflection coating technology, with a reflectivity of over 99.9%. The laser beam direction can be adjusted in the focusing optical path. The laser source power, irradiation duration, and irradiation frequency can all be controlled by the irradiation software built into the control unit, thereby controlling the output power between 0-60 W. The control unit includes a controller 17 and a processor 18. The controller 17 is communicatively connected to the three-dimensional stress measurement device, the focused laser irradiation device, and the processor 18. The controller 17 controls the three-dimensional stress measurement device to measure and output the three-dimensional distribution data of residual stress inside the optical element to be processed and transmits it to the processor 18. The processor 18 identifies the target point and generates the corresponding three-dimensional coordinates. The controller 17 controls the focused laser irradiation device to move the laser beam focus to the three-dimensional coordinates of the target point and irradiate the optical element to be processed. It should be noted that the processor 18 integrates software for three-dimensional image reconstruction, stress analysis, target point localization, path planning, irradiation control, and motion control.

[0026] The multi-axis precision motion platform 9 includes a clamping stage (not shown in the figure) and a three-dimensional displacement stage (not shown in the figure). The clamping stage is adaptable to mounting optical components with a circumscribed circle diameter ≤200mm, such as... Figure 4 As shown, the three-dimensional displacement stage uses three high-precision unidirectional moving displacement stages to control the movement in the XYZ directions. At the same time, a nano-piezoelectric device is used to assist in the micro-displacement control in the Z-axis direction. The combined control can make the displacement accuracy in the X, Y, and Z directions reach ±1μm, ±1μm, and ±0.05μm, respectively. The beam collector 10 is used to absorb or capture the laser beam, and the beam collector 10 is respectively disposed on both sides of the multi-axis precision motion platform 9 along with the focused laser irradiation device and / or the three-dimensional stress measurement device.

[0027] The process of the selective elimination method for residual stress inside optical elements provided by this invention is as follows: (1) Place the optical element to be processed on the clamping stage in the multi-axis precision motion platform 9, start the three-dimensional stress measurement device to perform a full three-dimensional scan of the optical element to be processed, and obtain three-dimensional stress image data. The scanning range is the entire volume of the element, the axial scanning step is 2μm, and the radial scanning trajectory is acquired using a spiral trajectory. (2) Based on the three-dimensional reconstruction software integrated in the processor 18, stress data is extracted and three-dimensional reconstruction is performed on the three-dimensional stress image data. The reconstructed three-dimensional slice stress data along the axis is obtained, from which the full-field three-dimensional stress tensor distribution data inside the optical element to be processed can be obtained. The data is represented by the magnitude of the stress value (magnitude is represented by color depth) and direction (represented by different colors). The stress unit is MPa, such as Figure 3 As shown, Figure 3 The diagram shows the three-dimensional stress tensor distribution data of a certain optical element to be processed; (3) After the three-dimensional reconstruction is completed, the target point positioning software and stress software analysis are started to identify the stress concentration areas where the residual stress exceeds the preset gradient threshold (in this embodiment, the three gradient thresholds are set to 15MPa, 10MPa and 5MPa respectively, and the stress concentration area is divided into the first stress concentration area exceeding 15MPa, the second stress concentration area of ​​15-10MPa and the third stress concentration area of ​​10-5) as the target point. The stress value and the three-dimensional spatial coordinates (X, Y, Z) with the initial position as the origin are recorded respectively, and the three-dimensional spatial coordinates (X, Y, Z) are converted into spatial coordinates (X1, Y1, Z1) with the focused spot of the irradiation source as the origin. (4) After the target point is located, the irradiation control software integrated in the three-dimensional displacement stage and processor 18 begins to run, such as Figure 4As shown, the three-dimensional displacement stage is moved to the recorded spatial coordinates (X1, Y1, Z1), and the irradiation control software is started. Based on the preheating experiment, the power range is determined to be 5W-15W. For this embodiment, different power is selected for the target points corresponding to different stress concentration areas. The target point corresponding to the first stress concentration area with residual stress exceeding 15MPa is selected with a power of 10W, and the target point corresponding to the second stress concentration area with residual stress between 15-5MPa is selected with a power of 5W. The irradiation time of a single target point can also be selected according to different stress gradients. In this embodiment, the irradiation time of the target point with residual stress of 15MPa is set to 2.5 seconds, the irradiation time of the target point with residual stress between 15-10MPa is set to 1.0 second, and the irradiation time of the target point with residual stress between 10-5MPa is set to 1.0 second. By controlling the irradiation duration and power, the temperature in different stress concentration areas can be raised to between the strain point (approximately 1100°C) and softening point (approximately 1600°C) of fused silica glass. In this embodiment, the specific temperature rise is 1200°C, which reduces and eliminates residual stress inside the optical element to be processed. After laser irradiation of one target point is completed, the laser source will be turned off and wait for the three-dimensional displacement stage to move to the next irradiation target point according to the preset scanning path before being turned on again. In this way, the target points are irradiated one by one. (5) After the irradiation of each target point is completed, the system will re-perform on-orbit stress detection. The three-dimensional scanning software will re-collect the stress information of the target point after irradiation. At this time, it is not a full-area scan of the element. The stress information obtained after scanning will be reconstructed and the target point position will be reselected through three-dimensional reconstruction software and target point positioning software. If a stress concentration area with residual stress exceeding the preset gradient threshold is still identified, the above steps (3) and (4) will be repeated for stress irradiation. If the residual stress does not exceed the preset gradient threshold, it is determined that the residual stress of the optical element meets the usage requirements and the system stops working.

[0028] It should be noted that the system can further selectively eliminate residual stress by adjusting various parameters, thereby controlling the stress amplitude to be further reduced.

[0029] Example 1 A calcium fluoride lens already mounted in a metal frame was selected. Due to assembly stress, localized stress concentration occurred in the edge region of this calcium fluoride lens, and the aforementioned method for selectively eliminating residual stress within optical elements was used. The stress detection light source 5 has an axial resolution of 2.5 μm, the laser source 1 has a wavelength of 10.6 μm, a power of 8 W, and a focused spot diameter of 5 μm. The stress detection light source 5 scanned and identified four stress concentration areas near the contact point of the lens frame, such as... Figure 5As shown in Figure a, the stress peak values ​​of the three stress concentration areas are all greater than 8 MPa, and the overall stress peak value of the lens is 9.5 MPa. A CO2 laser with a wavelength of 10.6 μm (calcium fluoride absorbs well at this wavelength) is used, with a laser power of 1.5 W and an irradiation time of 0.5 seconds / point. The laser beam focus is precisely positioned on the stress point inside the lens material (not the frame or surface).

[0030] The calcium fluoride lens was re-scanned after irradiation treatment, such as... Figure 5 As shown in b, the stress peak values ​​in the stress concentration area are all less than 5 MPa, and the overall stress peak value of the lens is 4.1 MPa. The stress peak value is reduced by more than 56%, and the edge stress concentration is significantly alleviated. Furthermore, the lens surface coating and the lens frame are undamaged as detected by microscope and surface profilometer. Thus, Example 1 demonstrates that the present invention has the unique ability to perform in-situ, "minimally invasive surgery"-style repair of integrated components, which cannot be achieved by overall annealing or surface impact methods.

[0031] Comparative Example 1 The sample of Example 1 was processed using the CN115874120A method (simulation + defocusing). Based on the material properties of the sample and the assumed cooling process parameters, finite element simulation was performed to obtain the "predicted" stress distribution cloud map. Based on the cloud map, the surface scanning path of the defocused laser (spot diameter 1mm) was planned, and the laser with the same power (8W) as in Example 1 was used to scan the sample surface.

[0032] Combine the "predicted" stress distribution cloud map with Figure 5 A comparison of the physical measurement images revealed a significant deviation in stress distribution between the two. Furthermore, a rescan of the laser-treated sample in Comparative Example 1 showed changes in stress within 500 μm below the surface, but the stress point at a depth of 3 mm (the target point in Example 1) was almost unaffected, with the stress decreasing by only about 8%. Thus, Comparative Example 1 demonstrates that relying on simulation predictions leads to inaccurate target processing, and that the defocused surface treatment mode cannot effectively affect the stress deep within the component.

[0033] Comparative Example 2 The samples in Example 1 were treated using traditional overall heat treatment annealing. The fused silica samples from the same batch were placed in an annealing furnace and treated according to the standard process (heating to 1150°C at 5°C / min, holding for 10 hours, and then slowly cooling to room temperature at 1°C / min).

[0034] Stress testing of the treated samples revealed a decrease in the overall average stress level. However, due to the uneven distribution of the original stress, the stress in the high-stress areas was not completely eliminated after overall annealing, while the low-stress areas developed slight new thermal stress due to prolonged high-temperature treatment. The improvement in stress distribution uniformity was limited. More importantly, the samples underwent overall surface deformation (warping), which is unacceptable for precision optical components. Therefore, as can be seen from Comparative Example 2, overall annealing faces a bottleneck in improving stress uniformity and inevitably introduces uncontrollable overall deformation.

[0035] The foregoing has provided a detailed description of a method and system for selectively eliminating residual stress inside an optical element, as provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application; the descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for selectively eliminating residual stress inside an optical element, characterized in that, The method includes the following steps: S100, Three-dimensional stress mapping: Based on the three-dimensional stress distribution measurement device, the optical element to be processed is scanned to obtain the three-dimensional distribution data of the residual stress inside the optical element to be processed; S200, Target Location: Based on the acquired three-dimensional distribution data of residual stress, identify and determine the three-dimensional spatial coordinates of at least one target point inside the optical element to be processed. S300, Internal Focused Laser Irradiation: Based on the three-dimensional spatial coordinates, the laser beam is controlled to pass through a high numerical aperture focusing system, and its focus is guided and positioned at the corresponding target point inside the optical element to be processed for irradiation, so as to eliminate the residual stress of the target point.

2. The method for selectively eliminating residual stress inside an optical element according to claim 1, characterized in that, In step S300, the laser parameters of the laser beam are controlled to make the temperature at the target point reach a predetermined temperature between the strain point and softening point of the optical element to be treated.

3. The method for selectively eliminating residual stress inside an optical element according to claim 1, characterized in that, During or between steps S300, the stress state of the target point is measured again, and the laser irradiation parameters are dynamically adjusted or it is decided whether to perform supplementary irradiation based on the results of the remeasurement.

4. The method for selectively eliminating residual stress inside an optical element according to claim 1, characterized in that, In step S300, the focus of the laser beam is stationary at a single target point, or it irradiates a local three-dimensional spatial region composed of multiple target points.

5. The method for selectively eliminating residual stress inside an optical element according to claim 1, characterized in that, Step S100 and step S300 are executed by sharing the same optical path system of the same high numerical aperture objective lens.

6. A selective elimination system for implementing the method according to any one of claims 1-5, characterized in that, include: A three-dimensional stress measurement device is used to scan the optical element to be processed and output the three-dimensional distribution data of residual stress inside the optical element to be processed. A focused laser irradiation device includes a laser source and a focusing optical path, used to generate a laser beam and position the focal point of the laser beam at a three-dimensional spatial point inside the optical element to be processed; The control unit, which is communicatively connected to the three-dimensional stress measurement device and the focused laser irradiation device, is configured to: identify the target point and generate the corresponding three-dimensional coordinates based on the residual stress three-dimensional distribution data output by the three-dimensional stress measurement device; and control the focused laser irradiation device to move the laser beam focus to the three-dimensional coordinates of the target point and perform irradiation.

7. The selective elimination system according to claim 6, characterized in that, The optical paths of the three-dimensional stress measurement device and the focused laser irradiation device are combined by a beam splitter and finally output to the optical element to be processed through the same high numerical aperture objective lens.

8. The selective elimination system according to claim 6, characterized in that, The three-dimensional stress measurement device is a phase-sensitive optical coherence tomography system or a photoelastic scanning system.

9. The selective elimination system according to claim 6, characterized in that, The laser source of the focused laser irradiation device is a continuous wave or long pulse laser, and its output wavelength corresponds to the absorption band of the optical element material to be processed.

10. The selective elimination system according to claim 6, characterized in that, It also includes a multi-axis precision motion platform for carrying the optical element to be processed. The control unit coordinates and controls the multi-axis precision motion platform and the focusing optical path of the focused laser irradiation device to realize the positioning of the focal point of the laser beam in the three-dimensional space inside the optical element to be processed.

Images