A method for 3D sapphire surface grinding

Abstract

The application discloses a 3D sapphire surface frosted method, and relates to the technical field of sapphire processing. The method first uses a 3D camera to perform overall scanning on a sapphire workpiece to be processed to generate a three-dimensional contour model; then, an ultraviolet ultrashort pulse laser is used to perform global scanning on the 3D curved surface of the sapphire workpiece to realize a frosted effect; in the scanning process, a laser control system controls the ultraviolet ultrashort pulse laser and a dynamic focusing module according to the model, so that the laser spot is always focused vertically on the surface of the 3D curved surface and the spot size remains unchanged; finally, ultrasonic cleaning and drying are performed to obtain a frosted piece with Ra of 200-250 nm. The application solves the problems of uneven frosted effect and great damage of traditional processes on the 3D curved surface, and realizes low thermal damage, delicate and uniform frosted effect and high-precision processing.

Description

Technical Field

[0001] This invention relates to the field of sapphire processing technology, and more particularly to a process for frosting the surface of 3D sapphire using laser. This process can be widely applied in high-end displays, optical components, and precision ceramic manufacturing. Background Technology

[0002] Sapphire is widely used in consumer electronics, optical instruments, and other fields due to its high hardness, high light transmittance, and excellent wear resistance. With product design trending towards 3D curved surfaces, frosting the surface of 3D sapphire to achieve specific tactile and optical effects has become a new industry demand.

[0003] Currently, the main traditional processes for surface finishing of sapphire are mechanical grinding and blasting, and chemical etching. Mechanical grinding and blasting creates a rough surface by high-speed impact of abrasive particles. While effective for planar sapphire, it suffers from uneven abrasive distribution and inconsistent texture in complex 3D curved surfaces. Furthermore, mechanical impact can generate subsurface microcracks and chipping defects, reducing the structural strength of sapphire components. It also results in high abrasive consumption and severe dust pollution, making it unsuitable for high-precision 3D component processing. Chemical etching uses strong acids and alkalis to etch the sapphire surface, creating a microscopic rough structure. This process suffers from environmental pollution from the etching solution, high waste treatment costs, and poor corrosion control. It cannot precisely control the fineness of the finish and is prone to over-etching edges and corners of 3D curved surfaces, compromising dimensional accuracy. Additionally, chemical etching can lead to surface corrosion spots, affecting the uniformity of the appearance.

[0004] Existing technologies include some attempts at laser processing of sapphire surfaces, but most of these are for drilling, cutting, or roughening flat sapphire surfaces, and typically employ long-pulse infrared lasers. Long-pulse infrared laser processing suffers from problems such as a large heat-affected zone, a thick surface recast layer, and a tendency to generate thermal cracks. Furthermore, existing laser processes lack dynamic path and focus control for the contour undulations of 3D curved surfaces, making it impossible to achieve uniform frosting across the entire 3D curved surface. This makes it difficult to meet the processing requirements of high-end products for consistent frosting texture, low damage, and high precision.

[0005] In summary, existing 3D sapphire surface grinding processes suffer from technical defects such as poor surface adaptability, significant processing damage, weak controllability, insufficient environmental friendliness, and low grinding uniformity. There is an urgent need to develop a laser grinding process that is adaptable to complex 3D surfaces, has low thermal damage, precise and controllable texture, and is green and efficient, in order to solve the bottleneck problems of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a process for grinding the surface of 3D sapphire using laser, so as to solve the technical problems of poor surface adaptability, uneven grinding, large processing damage and insufficient environmental protection in the existing process of grinding curved surfaces of 3D sapphire.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A 3D sapphire surface frosting method includes the following steps: using a 3D camera to perform a full-area scan of the sapphire workpiece to be processed, capturing height differences at different locations to generate a three-dimensional contour model; using an ultraviolet ultrashort pulse laser to perform a full-area scan of the 3D curved surface of the sapphire workpiece to achieve a frosting effect; the specific parameters of the laser are: a fill gap of 4-6 μm, an energy density of 200-300 μJ / mm², and a scanning speed of 800-1200 mm / s; during the scanning process, the laser control system controls the ultraviolet ultrashort pulse laser and the dynamic focusing module according to the three-dimensional contour model, so that the laser spot is always vertically focused on the 3D curved surface of the sapphire workpiece, and the spot size remains unchanged.

[0008] Furthermore, the wavelength of the ultraviolet ultrashort pulse laser is 355nm, the pulse width is no more than 10ps, and the repetition frequency is 50-200kHz.

[0009] Furthermore, the method of using an ultraviolet ultrashort pulse laser to perform full-area scanning of the 3D curved surface of the sapphire workpiece includes: The sapphire workpiece undergoes laser grinding using a step-by-step scanning mode with decreasing energy and increasing speed. This step-by-step scanning mode sequentially includes a coarse grinding process, a fine grinding process, and a repair grinding process to achieve precise control over the graded grinding texture. The coarse grinding process performs a full-area scan of the 3D curved surface, with specific parameters: a fill spacing of 6-8 μm, an energy density of 300-400 μJ / mm², and a scanning speed of 500-800 mm / s. The fine grinding process performs a second full-area scan of the 3D curved surface, with specific parameters: a fill spacing of 4-6 μm, an energy density of 200-300 μJ / mm², and a scanning speed of 800-1200 mm / s. The repair and sanding process involves repeated light-emitting scanning to repair the easily machinable uneven areas on the 3D curved surface. The specific parameters are: filling spacing of 2-4μm, energy density of 100-200μJ / mm², and scanning speed of 1200-1500mm / s.

[0010] Furthermore, before the full-area scanning, a uniformly permeable oil is sprayed onto the surface of the sapphire workpiece. The permeable oil eliminates air gaps by matching the refractive index, reduces interface reflection and scattering, and fills micro gaps and isolates air bubbles to construct a continuous and uniform optical path, thereby refining the surface micro-nano structure and improving the fineness of the frosted texture.

[0011] Furthermore, the permeable oil is one of fluorinated silicone oil, perfluoropolyether, or low-aromatic synthetic UV oil; the permeable oil has a transmittance of not less than 90% for a wavelength of 355nm at a 1cm optical path, a refractive index of 1.37-1.42, and a viscosity of 50-150cSt; the target oil film thickness for spraying the permeable oil is 1-2μm.

[0012] Furthermore, the linkage control between the laser control system and the 3D camera and the dynamic focusing module includes, in sequence: 3D camera point cloud acquisition, host computer software preprocessing, three-dimensional coordinate mapping, optical geometry calculation, hardware real-time interpolation, and analog drive signal output, so as to synchronously control the deflection of the X-mirror and Y-mirror and the focusing of the dynamic focusing module throughout the process.

[0013] Furthermore, the dynamic focusing module includes a movable lens and a regular focusing lens capable of moving along the Z-direction; as the scanning position changes, focus compensation is achieved by finely adjusting the distance between the movable lens and the regular focusing lens, ensuring that the spot diameter of the laser beam away from the origin remains consistent with the spot diameter at the origin, thus ensuring focusing accuracy on the scanning plane; during the processing, a coaxial focus sensor coaxially collects reflected light to determine whether the focus falls on the workpiece surface, and the Z-direction focusing voltage is finely adjusted in real time to ensure that the defocus tolerance is no greater than ±0.02mm.

[0014] Furthermore, during the full-area scanning process, air is synchronously introduced into the processing area through a gas nozzle at a flow rate of 0.5-1 L / min.

[0015] Furthermore, after the full-area scanning is completed, a post-processing step is also included: ultrasonic cleaning of the sapphire workpiece with pure water and a chemical agent respectively, followed by drying treatment at a temperature of 65°C to 80°C for 12 to 30 minutes, finally obtaining a sapphire frosted part with a surface roughness Ra of 200-600nm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention utilizes a 3D camera to scan and generate a three-dimensional contour model, and links it with a dynamic focusing module to solve the problem that traditional processes cannot achieve uniform sanding on 3D curved surfaces. The dynamic focusing module can adjust the focus position in real time according to the height difference of the 3D curved surface, ensuring that the laser spot is always vertical and accurately focused on the curved surface, effectively avoiding uneven local processing caused by defocusing or off-focus.

[0017] (2) The present invention uses ultraviolet ultra-short pulse laser (pulse width ≤10ps), which belongs to the category of "cold processing" compared with traditional long pulse infrared laser. Its heat-affected zone is extremely small (≤5μm), which can effectively avoid 3D structural deformation and microcracks caused by thermal stress in sapphire material during processing, greatly reducing processing damage and improving product yield. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of the overall steps of a 3D sapphire surface grinding method according to the present invention.

[0020] Figure 2 This is a schematic diagram of the sapphire frosting effect in Embodiment 2 of the present invention.

[0021] Figure 3 This is a schematic diagram illustrating the frosted effect of sapphire as a comparative example of the present invention. Detailed Implementation

[0022] 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, this embodiment of the invention provides a method for frosting the surface of 3D sapphire using a laser. The method specifically includes the following steps: A 3D camera is used to scan the sapphire workpiece to be processed, capturing the height differences at different locations to generate a three-dimensional contour model. The three-dimensional contour model is then fed back to the laser control system to solve the problem of uneven processing caused by the difficulty in obtaining 3D curved surface contours in traditional processes. A UV ultra-short pulse laser was used to perform full-area scanning of the 3D curved surface of a sapphire workpiece to achieve a frosted effect. The specific parameters of the laser were: fill gap of 4-6μm, energy density of 200-300μJ / mm², and scanning speed of 800-1200mm / s. During the scanning process, the laser control system controls the ultraviolet ultra-short pulse laser and the dynamic focusing module according to the three-dimensional contour model, so that the laser spot is always vertically focused on the 3D curved surface of the sapphire workpiece, and the spot size remains unchanged, so as to avoid local processing unevenness caused by defocusing or off-focus.

[0024] Specifically, the above method includes the following steps: (1) 3D contour scanning and modeling A 3D camera is used to scan the sapphire workpiece to be processed, capturing height differences at different locations to generate a 3D contour model. This generated 3D contour model is then fed back to the laser control system. This step is fundamental to achieving uniform 3D surface processing, solving the problem of traditional processes being unable to obtain accurate surface morphology.

[0025] (2) Laser parameter setting and dynamic focusing control In this embodiment of the invention, an ultraviolet ultrashort pulse laser is used as the processing light source. The laser wavelength is set to 355nm, the pulse width is no more than 10ps, and the repetition frequency is 50-200kHz. The role of the ultrashort pulse laser is to reduce the heat-affected zone during processing to within 5μm, thereby avoiding 3D structure deformation and microcrack formation.

[0026] The laser control system uses the 3D contour model generated by the 3D camera to control the 3D camera and the dynamic focusing module in a coordinated manner. The specific data processing flow is divided into six levels: First, the 3D camera acquires point clouds; second, millisecond-level preprocessing is performed in the PC host computer software; then, 3D coordinate mapping and optical geometry calculation are performed to convert the coordinates into mechanical deflection; next, microsecond-level hardware real-time motion interpolation is performed through FPGA or real-time control card; then, the digital signal is converted into an analog drive signal output; finally, the actuator is driven to respond, synchronously controlling the deflection of the X and Y mirrors and the focusing of the dynamic focusing module throughout the process.

[0027] The dynamic focusing module includes a movable lens that can move along the Z-axis and a fixed ordinary focusing lens. As the scanning position changes, the system achieves focus compensation by fine-tuning the distance between the movable lens and the ordinary focusing lens, ensuring that the laser beam spot diameter, away from the origin, is once again the same as the spot diameter at the origin. This ensures focusing accuracy on the scanning plane. After scanning by the X-mirror and Y-mirror, the laser beam is focused onto the surface of the workpiece. Simultaneously, during processing, a coaxial focus sensor coaxially collects reflected light to determine if the focus falls on the sapphire workpiece surface, and fine-tunes the Z-axis focusing voltage in real time to control the defocus tolerance to no more than ±0.02mm, guaranteeing that the laser spot is always perpendicularly focused on the 3D curved surface.

[0028] (3) Laser grinding In some embodiments of the present invention, a step-by-step scanning mode with decreasing energy and increasing speed is adopted to complete the laser grinding process in three steps. Specifically, it includes: (a) Coarse grinding process: using high energy density and low scanning speed parameters. Specifically, the fill spacing is set to 6-8μm, the energy density is 300-400μJ / mm², and the scanning speed is 500-800mm / s. This process performs a full-area scan on the 3D curved surface, aiming to efficiently remove the original damage layer and polishing marks on the surface of the sapphire workpiece and form a uniform micro-rough substrate. (b) Fine grinding process: a uniform penetrating oil (such as baby oil or special fluorinated silicone oil, etc.) is sprayed onto the product surface. The target oil film thickness is controlled at 1-2μm. The spraying process parameters can be set as follows: nozzle diameter 0.6-0.8mm, atomizing air pressure 1.1-1.3bar, spraying distance 150-180mm, gun speed 400-800mm / s, leveling time 5-6min, and drying conditions of 70℃-80℃ for 12 minutes. Subsequently, a fine sanding process is performed by reducing the energy density and increasing the scanning speed, setting the fill gap to 4-6μm, the energy density to 200-300μJ / mm², and the scanning speed to 800-1200mm / s. This process performs a second scan on the surface after coarse sanding to refine the surface micro-nano structure and eliminate local roughness and unevenness caused by coarse sanding. (c) Repair sanding process: First, clean the permeable oil from the product surface, then spray a uniform permeable oil again, and then dry. Next, the energy density is further reduced and the scanning speed is increased for repair and frosting processing. The fill spacing is set to 2-4 μm, the energy density to 100-200 μJ / mm², and the scanning speed to 1200-1500 mm / s. This process involves repeated light-emitting scans to repair easily machinable uneven areas on the 3D curved surface, in order to balance the overall frosting effect and ensure uniform frosting across the entire surface. "Easily machinable uneven areas" refer to regions on the 3D curved surface determined by an empirically set curvature threshold, typically including areas of abrupt curvature changes, edges, and corners. In practical applications, marker points can be set in the 3D contour model at locations where the curvature threshold changes, with the "easily machinable uneven areas" starting from these marker points, thus automatically locating the scanning position for the repair and frosting process. By adjusting the energy density and scan line spacing of each process, frosting texture gradations can be achieved. High energy density and fine line spacing correspond to a delicate frosting effect, while low energy density and coarse line spacing correspond to a rough frosting effect, meeting the needs of different scenarios.

[0029] In other embodiments of the present invention, a single-scan method is used to perform a full-area scan of the 3D curved surface of the sapphire workpiece to achieve a frosted effect. The specific parameters of the laser are: a fill spacing of 4-6 μm, an energy density of 200-300 μJ / mm², and a scanning speed of 800-1200 mm / s. This parameter range is the same as that of the fine grinding process described above, with lower energy and higher scanning speed, achieving a single fine processing scan without the need for rough grinding and repair grinding processes, resulting in shorter processing time and higher mass production efficiency. In addition, the single-scan pulse action time is short, the heat accumulation is extremely low, and the risk of cracks, hidden cracks, and edge chipping is low.

[0030] Whether using single-step or multi-step scanning, air can be synchronously introduced into the processing area through gas nozzles throughout the entire processing, with an airflow rate of 0.5-1 L / min. The purpose of introducing air is to promptly remove residues generated by laser ablation, preventing secondary adhesion of residues to the workpiece surface, while also lowering the temperature of the processing area and further reducing the heat-affected zone.

[0031] Furthermore, regardless of whether it's single-step scanning or distributed scanning, a uniformly applied transmissive oil can be sprayed onto the surface of the sapphire workpiece before scanning. This transmissive oil eliminates air gaps through refractive index matching, reduces interface reflection and scattering, and fills micro-gaps and isolates air bubbles to construct a continuous and uniform optical path, thereby refining the surface micro / nano structure and improving the smoothness of the frosted texture. In some specific embodiments of this invention, a step-by-step scanning method is used, where a uniformly applied transmissive oil is sprayed onto the surface of the sapphire workpiece before both the fine grinding process and the repair grinding process. Preferably, a 355nm-specific transmissive oil is used, such as fluorinated silicone oil, perfluoropolyether, or low-aromatic synthetic UV oil. It has a transmittance of no less than 90% for a 355nm wavelength at a 1cm optical path, low absorption in the 200-400nm UV band, a refractive index of 1.37-1.42, and a low viscosity of 50-150cSt, making it easy to spread and quickly remove air bubbles. The core principle of oil-based processing is refractive index matching. By eliminating air gaps, reducing interface reflection and scattering, and filling micro-gaps to isolate air bubbles, a continuous and uniform optical path is constructed, eliminating optical path breaks and significantly improving the smoothness of the frosted texture. If the laser scanning parameters exceed the above-mentioned step-by-step parameter range, the laser processing efficiency will be too low, making it impossible to eliminate processing traces from previous processes, severely affecting the final processing effect.

[0032] (d) Post-processing steps After the sanding is completed, the sapphire workpiece is ultrasonically cleaned with pure water and chemical agents for about 5 minutes each; then it is dried at a low temperature of 65℃ to 80℃ for 12 to 30 minutes to finally obtain a 3D sanded sapphire workpiece with a surface roughness Ra of 200-600nm.

[0033] To more intuitively illustrate the beneficial effects of the present invention, the following specific embodiments and comparative experimental data are provided: Example 1: A 5W UV PS laser was selected, with a fixed pulse width of 10 ps, ​​a wavelength of 355 nm, and a repetition rate of 200 kHz. The test involved a single finishing process, a single scan, and no roughing. The specific workflow included: 1. Pre-treatment: 3D sapphire finished product (shape and curved surface polished), ultrasonically cleaned to remove surface polishing powder and oil, and dried.

[0034] 2. Clamping and positioning: The contour vacuum fixture collects the actual 3D curved surface by point cloud scanning, and imports it into the galvanometer system to perform surface mapping compensation to eliminate clamping deviation.

[0035] 3. Single-pass finishing (only laser process): Number of processing times: 1, energy density 280uJ, speed 800mm / s, frequency setting 200KHz, fill spacing 4um; only a single scan, no roughing, no repeated multi-layer scans, directly generating frosted microstructures.

[0036] 4. Cleaning: Ultrasonic cleaning + plasma cleaning removes a small amount of residual micro-debris from the surface, eliminating the need for grinding or sandblasting.

[0037] 5. Inspection: Ra is measured by 3D profilometer; CCD visual inspection: no scanning stripes, no local bright spots, no edge micro-chipping, and no micro-cracks.

[0038] Example 2: A 5W UV PS laser was selected, with a fixed pulse width of 10ps, a wavelength of 355nm, and a repetition frequency of 200kHz. The 3D sapphire workpiece to be processed was subjected to the following processing: Coarse grinding process: energy density 380μJ / mm², scanning speed 600mm / s, fill spacing 6μm; Fine grinding process: Spray a uniform penetrating oil (oil film thickness 1.5μm), energy density 280μJ / mm², scanning speed 800mm / s, and filling gap 4μm; Repair and sanding process: After cleaning, re-spray a uniform penetrating oil with an energy density of 180μJ / mm², a scanning speed of 1200mm / s, and a fill spacing of 3μm.

[0039] like Figure 2 As shown, after post-treatment cleaning and drying, the surface roughness Ra value of the product is measured to be 200-250nm, and the visually uniform frosting effect is very uniform with no unevenness.

[0040] Comparative experiment: The same laser parameters as in Example 2 were used for a three-step process, the difference being that the control group did not spray penetrating oil in the fine grinding and repair grinding processes.

[0041] Table 1 shows a comparative analysis of the single-step scanning method in Example 1 and the step-by-step scanning method in Example 2. As can be seen from Table 1, the choice between the step-by-step scanning method and the single-step scanning method is essentially a trade-off between process compatibility and processing efficiency. The step-by-step scanning method employs a multi-round strategy of "coarse scanning + fine scanning + local repair," which has the advantages of a wide process window, high tolerance to equipment dynamic performance, and the ability to achieve a uniform frosting effect with a common Gaussian beam. However, the continuous accumulation of heat from multiple scanning rounds poses a higher risk of heat accumulation, easily leading to defects such as cracks and bright marks. Simultaneously, the processing time is significantly increased, and the risk of edge chipping is also greater due to the stress accumulation effect. In contrast, the single-step scanning method completes the processing with a single near-threshold scan. With its extremely short pulse duration, it controls heat accumulation to a low level, significantly reducing the risk of cracks and hidden cracks. Moreover, its processing efficiency is 40%–60% higher than that of the step-by-step method, and the risk of edge chipping is also smaller due to the energy derating design. However, its process window is extremely narrow, with the energy density in the critical range between the ablation threshold and the crack threshold. The parameter tolerance is low, and even a small parameter deviation can lead to defects such as bright surfaces or cracks, making the control precision requirements extremely stringent.

[0042] Table 1

[0043] The comparative experimental results of spraying and not spraying penetrating oil showed that the experimental group with penetrating oil had an Ra value of 200nm-250nm and a visually uniform frosted effect; while the control group without penetrating oil had an Ra value of 300nm-450nm, such as... Figure 3 As shown, the visual appearance reveals varying degrees of matte finish, with obvious microstructural breaks on the surface. This fully demonstrates the significant advancement of the spray-coating through-oil combined with energy-reducing step-scanning process in improving the fineness and uniformity of sapphire matte finish.

[0044] The above are merely specific embodiments of the present invention and should not be construed as limiting the scope of the present invention. Equivalent variations made by those skilled in the art based on this invention, as well as changes well-known to those skilled in the art, should still fall within the scope of the present invention.

Claims

1. A method for frosting the surface of 3D sapphire, characterized in that, Includes the following steps: A 3D camera is used to scan the sapphire workpiece to be processed, capturing the height differences at different locations to generate a three-dimensional contour model. A UV ultra-short pulse laser was used to perform full-area scanning of the 3D curved surface of a sapphire workpiece to achieve a frosted effect. The specific parameters of the laser were: fill gap of 4-6μm, energy density of 200-300μJ / mm², and scanning speed of 800-1200mm / s. During the scanning process, the laser control system controls the ultraviolet ultra-short pulse laser and the dynamic focusing module according to the three-dimensional contour model, so that the laser spot is always vertically focused on the 3D curved surface of the sapphire workpiece, and the spot size remains unchanged.

2. The 3D sapphire surface grinding method according to claim 1, characterized in that, The ultraviolet ultrashort pulse laser has a wavelength of 355nm, a pulse width of no more than 10ps, and a repetition frequency of 50-200kHz.

3. The 3D sapphire surface frosting method according to claim 1, characterized in that, The method of using an ultraviolet ultrashort pulse laser to perform full-area scanning of the 3D curved surface of a sapphire workpiece includes: The sapphire workpiece is laser-polished using a step-by-step scanning mode with decreasing energy and increasing speed. The step-by-step scanning mode includes a coarse polishing process, a fine polishing process, and a repair polishing process in sequence, so as to achieve precise control of the graded polishing texture. The coarse sanding process performs a full-area scan on the 3D curved surface, with the following specific parameters: fill spacing of 6-8μm, energy density of 300-400μJ / mm², and scanning speed of 500-800mm / s. The fine grinding process performs a second full-area scan on the 3D curved surface. The specific parameters are: fill spacing of 4-6μm, energy density of 200-300μJ / mm², and scanning speed of 800-1200mm / s. The repair and sanding process involves repeated light-emitting scanning to repair the easily machinable uneven areas on the 3D curved surface. The specific parameters are: filling spacing of 2-4μm, energy density of 100-200μJ / mm², and scanning speed of 1200-1500mm / s.

4. The 3D sapphire surface frosting method according to claim 1, characterized in that, Before the full-area scanning, a uniformly permeable oil is sprayed onto the surface of the sapphire workpiece. The permeable oil eliminates air gaps by matching the refractive index, reduces interface reflection and scattering, and fills micro gaps and isolates air bubbles to construct a continuous and uniform optical path, thereby refining the surface micro-nano structure and improving the fineness of the frosted texture.

5. The 3D sapphire surface grinding method according to claim 4, characterized in that, The permeable oil is one of fluorinated silicone oil, perfluoropolyether, or low-aromatic synthetic UV oil. The transmitted oil has a transmittance of not less than 90% for a wavelength of 355nm at a 1cm optical path, a refractive index of 1.37-1.42, and a viscosity of 50-150cSt. The target oil film thickness for spraying the permeable oil is 1-2 μm.

6. The 3D sapphire surface grinding method according to claim 1, characterized in that, The linkage control between the laser control system and the 3D camera and the dynamic focusing module includes, in sequence: 3D camera point cloud acquisition, host computer software preprocessing, three-dimensional coordinate mapping, optical geometry calculation, hardware real-time interpolation, and analog drive signal output, so as to synchronously control the deflection of the X-mirror and Y-mirror and the focusing of the dynamic focusing module throughout the process.

7. The 3D sapphire surface grinding method according to claim 1, characterized in that, The dynamic focusing module includes a movable lens capable of moving along the Z direction and a regular focusing lens; As the scanning position changes, focus compensation is achieved by finely adjusting the distance between the moving lens and the ordinary focusing lens, so that the spot diameter of the laser beam away from the origin is consistent with the spot diameter of the origin, thus ensuring the focusing accuracy on the scanning plane. During the processing, a coaxial focus sensor is used to collect reflected light to determine whether the focus falls on the workpiece surface, and the Z-axis focusing voltage is finely adjusted in real time to ensure that the defocus tolerance is no more than ±0.02mm.

8. The 3D sapphire surface frosting method according to claim 1, characterized in that, During the full-area scanning process, air is synchronously introduced into the processing area through gas nozzles at a flow rate of 0.5-1 L / min.

9. The 3D sapphire surface frosting method according to claim 1, characterized in that, After the full-domain scan is completed, a post-processing step is also included: The sapphire workpiece is ultrasonically cleaned using pure water and a chemical agent, and then dried at 65°C to 80°C for 12 to 30 minutes to finally obtain a sapphire frosted part with a surface roughness Ra of 200-600 nm.

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