A method for processing super-smooth surface of micro-lens in groove

Abstract

This invention discloses a method for processing an ultra-smooth surface for microlenses within grooves. The method includes the following steps: first, cleaning and rough grinding of quartz glass to form a groove with microlenses; then, semi-finishing and finishing are performed sequentially using a diamond grinding wheel and a polycrystalline diamond tool; finally, cerium oxide polishing slurry is added to the groove, and the finished microlens is polished using a tapered wool wheel, followed by compensation processing. The cerium oxide polishing slurry contains 15-25 wt% cerium oxide, with an average particle size of 0.2-0.8 μm. The microlens processed using this method achieves a surface accuracy (PV) of 1.87 μm and a surface roughness (Ra) of 2.992 nm, meeting the stringent requirements for ultra-smooth surfaces in optical components.

Description

Technical Field

[0001] This invention relates to the field of optical micro / nano manufacturing technology, and in particular to a method for processing an ultra-smooth surface for microlenses within grooves. Background Technology

[0002] Microlens arrays, as a crucial component of optical micro / nano fabrication, are widely used in beam shaping, light field manipulation, micro-imaging, optical communication, and biomedical detection. To achieve superior optical performance, microlens surfaces typically need to reach ultra-smoothness levels (e.g., roughness Ra < 10 nm, surface accuracy PV < 15 μm). Currently, methods for fabricating ultra-smooth surfaces mainly include single-point diamond turning, precision grinding, mechanical polishing, and magnetorheological polishing. However, these methods are mostly suitable for processing lenses with open, continuous curved surfaces or rotating structures, and their effectiveness remains insufficient for processing non-rotating, deeply recessed embedded microlenses.

[0003] In related technologies, when microlenses are located inside grooves (such as microlenses in a circumferential array within a groove in a quartz glass substrate), conventional ultra-precision machining methods are difficult to apply directly to the lens surface due to structural interference from the sidewalls of the groove. For example, single-point diamond milling machines cannot easily enter the groove for machining; while manual polishing is flexible, it is difficult to achieve uniform polishing due to structural obstructions on the lens sides, and it heavily relies on operator experience, resulting in poor consistency and repeatability, and easily leading to lens contour distortion; mechanical polishing lacks suitable small-sized, contour-following polishing tools for the microstructure within the groove, and there is currently no mature equipment available in the industry.

[0004] Therefore, there is an urgent need to develop an ultra-smooth surface processing method suitable for microlenses within groove structures, in order to overcome the processing difficulties caused by structural interference, achieve high-precision and high-uniformity polishing of the microlens surface, and at the same time ensure the accuracy and repeatability of the lens profile. Summary of the Invention

[0005] The present invention aims to provide an ultra-smooth surface processing method for microlenses in grooves, which can effectively solve the problem that manual polishing cannot reach the sidewalls and roots of the lens due to interference of the groove sidewall structure, and achieve high-precision and high-uniformity polishing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for processing an ultra-smooth surface for microlenses within grooves, comprising the following steps: S1. The quartz glass is cleaned and coarsely ground to form a groove with microlenses, and then semi-finished with a diamond grinding wheel. S2. Use a polycrystalline diamond tool to finish the semi-finished microlens; S3. Add cerium oxide polishing liquid into the groove, and polish the finely processed microlens with a conical wool wheel to obtain the desired result. The cerium oxide polishing solution contains 15-25 wt% cerium oxide, and the average particle size of the cerium oxide is 0.2-0.8 μm.

[0007] In some embodiments of the present invention, the diameter ratio of the groove to the microlens is 15~30mm:100~300μm.

[0008] In some embodiments of the present invention, the depth of the groove is 2 to 8 mm.

[0009] In some embodiments of the present invention, the radius of curvature of the microlens is 0.8 to 1.5 mm.

[0010] In some embodiments of the present invention, the cleaning includes removing surface contaminants using anhydrous ethanol.

[0011] In some embodiments of the present invention, the coarse grinding uses a diamond grinding wheel with a diamond particle size of 80~110μm.

[0012] In some embodiments of the present invention, the parameters for rough grinding are set as follows: rotational speed 15000~20000 rpm, feed rate 1800~2200 mm / min, depth of cut 0.02~0.08 mm, and a machining allowance of 0.08~0.12 mm is reserved on one side of the lens.

[0013] In some embodiments of the present invention, the semi-finishing process uses a diamond grinding wheel with a diamond particle size of 5~15μm.

[0014] In some embodiments of the present invention, the parameters for the semi-finishing are set as follows: rotational speed of 18000~22000 rpm, feed rate of 450~550 mm / min, depth of cut of 0.002~0.008 mm, and a finishing allowance of 0.01~0.03 mm reserved on one side of the lens.

[0015] In some embodiments of the present invention, the finishing parameters are set as follows: rotational speed 22000~25000 rpm, feed rate 95~105 mm / min, depth of cut 0.001~0.003 mm, and a polishing allowance of 0.004~0.006 mm reserved on one side of the lens.

[0016] In some embodiments of the present invention, the polishing parameters are set as follows: spindle speed of 8000~12000 rpm, feed rate of 200~400 mm / min, depth of cut of 0.01~0.03 mm, and polishing time of single lens of 10~20 min.

[0017] In this invention, a conical spherical wool wheel is used for pre-shaping. The shape of its end matches the curved surface of the microlens in the groove. During polishing, the wool wheel can follow the curvature change of the convex spherical surface of the lens and fit into the side wall and root area. This completely avoids the regional selective polishing defect of hand-held sponge polishing, which can only polish the top and cannot reach the side wall and root due to geometric interference.

[0018] In some embodiments of the present invention, the polishing process further includes data processing and compensation processing.

[0019] In some embodiments of the present invention, the data processing includes collecting the profile curve of the polished microlens and the theoretical profile curve, placing them on the same coordinate axis, dividing the curve into equal parts, calculating the difference between the division points, and compensating the difference back to the original theoretical curve to generate a new lens processing profile.

[0020] In some embodiments of the present invention, the compensation process includes repeating the rough grinding, semi-finishing, finishing, and polishing steps based on the lens processing contour.

[0021] In some embodiments of the present invention, the roughness Ra of the compensated microlens is less than 10 nm and the surface accuracy PV is less than 15 μm.

[0022] In some embodiments of the present invention, the roughness Ra of the compensated microlens is less than 5 nm, and the surface accuracy PV is less than 2 μm.

[0023] In some embodiments of the present invention, the cerium oxide polishing slurry further comprises a dispersant and a stabilizer.

[0024] In some embodiments of the present invention, the dispersant comprises ammonium polyacrylate.

[0025] Preferably, the amount of ammonium polyacrylate added is 0.2~0.8 wt%.

[0026] In some embodiments of the present invention, the stabilizer comprises nano-silica sol.

[0027] Preferably, the solid content of the nano-silica sol is 25-40%, and the particle size of the nano-silica is in the range of 10-30.

[0028] Preferably, the amount of nano-silica sol added is 4.2~4.8 wt%.

[0029] The method for ultra-smooth surface processing of microlenses within grooves according to embodiments of the present invention has at least the following beneficial effects: This invention employs rough grinding and semi-fine grinding with diamond wheels to form the microlens, followed by contour finishing using PCD tools. Finally, a conical spherical contouring wool wheel combined with cerium oxide polishing fluid is used for contour polishing. This effectively solves the problem of manual polishing being unable to reach the lens sidewalls and root due to interference from the groove sidewall structure. The microlens processed using this method achieves a surface accuracy (PV) of 1.87 μm and a surface roughness (Ra) of 2.992 nm, significantly superior to manual polishing methods, meeting the stringent requirements of optical components for ultra-smooth surfaces.

[0030] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of quartz glass in Embodiment 1 of the present invention; Figure 2 This is a diagram of the lens after rough grinding with a diamond wheel according to Embodiment 1 of the present invention; Figure 3 This is a lens image of Embodiment 1 of the present invention after being precision machined with a polycrystalline diamond (PCD) tool; Figure 4 This is a diagram of the lens after polishing with cerium oxide polishing solution according to Example 1 of the present invention; Figure 5 This is a schematic diagram of the groove and microlens of the glass after processing according to Embodiment 1 of the present invention, where A is a top view and B is a side sectional view; Figure 6 This is the original measured profile of the microlens after polishing in Embodiment 1 of the present invention; Figure 7 This is a surface shape error curve of the microlens in Embodiment 1 of the present invention after undergoing ultra-smooth surface processing. Figure 8 This is the roughness curve of the microlens in Embodiment 1 of the present invention; Figure 9 This is the roughness curve of the microlens in Embodiment 1 of the present invention; Figure 10 This is the roughness curve of the microlens after compensation processing in Embodiment 1 of the present invention; Figure 11 This is a microlens image of Comparative Example 1 of the present invention after manual polishing for 6 minutes; Figure 12 This is a microlens image of Comparative Example 1 of the present invention after manual polishing for 12 minutes; Figure 13 This is a microlens image of Comparative Example 1 of the present invention after manual polishing for 18 minutes; Figure 14 This is a microlens image of Comparative Example 1 of the present invention after manual polishing for 24 minutes; Detailed Implementation The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0032] In the description of this invention, the reference term "and / or" includes all and any combination of one or more of the associated listed items. For example, A and / or B includes (A and B) and (A or B).

[0033] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0034] Example 1: Cerium oxide polishing slurry This embodiment provides a method for processing an ultra-smooth surface for microlenses within a groove, specifically including the following:

[0035] 1. Workpiece preparation and clamping Processing object: This experiment uses quartz glass with dimensions of 28×28×5mm ( Figure 1 For example, we will perform subsequent processing on the sample.

[0036] Cleaning and Clamping: Wipe the surface of the quartz glass blank and the working surface of the vacuum suction cup fixture with a lint-free cloth soaked in anhydrous ethanol (purity ≥99.7%) to remove grease, dust, and other contaminants. After cleaning, dry with clean compressed air to avoid residual liquid affecting the adsorption effect. Then, place the quartz glass blank in the center area of ​​the vacuum suction cup fixture, ensuring the lower surface of the quartz glass blank is in contact with the suction cup sealing ring. Turn on the vacuum system and control the vacuum level to not be lower than -0.08MPa to ensure that the quartz glass blank does not shift or vibrate during processing.

[0037] 2. Rough machining The microlens was rapidly rough-ground using a D2 150# electroplated diamond grinding wheel. The spindle speed was controlled at 18000 rpm, the feed rate at 2000 mm / min, and the depth of cut at 0.05 mm. A 0.1 mm machining allowance was left on each side of the lens. After rough machining, a circular groove was formed in the center of the quartz glass, and the microlens within the groove was initially formed (e.g., Figure 2 As shown in the figure, its surface is frosted, with obvious grinding marks and microcrack layers, and the surface roughness Ra is about 1.583 μm.

[0038] 3. Lens semi-finishing Replace the electroplated diamond grinding wheel with a D2 1200# electroplated diamond grinding wheel, following the same roughing trajectory as described above, but reduce the feed rate and depth of cut to eliminate coarse cracks caused by rough grinding, and machine to the standard lens shape, reducing surface roughness. Specifically, control the electroplated diamond grinding wheel speed at 20,000 rpm, the feed rate at 500 mm / min, the depth of cut at 0.005 mm, and leave a 0.02 mm finishing allowance on each side of the lens.

[0039] During machining, care should be taken to maintain constant contact between the grinding wheel and the workpiece surface to avoid contour distortion caused by elastic tool deflection. After semi-finishing, the micro-cracks generated by rough grinding are basically eliminated, the lens contour accuracy is increased, the surface roughness is reduced to Ra of about 0.387μm, and the surface is matte.

[0040] 4. Lens precision machining Finishing was performed using a polycrystalline diamond (PCD) tool with model number D0.8 R0.1, where the tip radius was 0.1 mm and the tool diameter was 0.8 mm.

[0041] During the finishing process, micro-milling or micro-turning is used to refine the microlens along its generatrix. At the same time, the PCD tool speed is controlled at 24,000 rpm, the feed rate is 100 mm / min, the depth of cut is 0.002 mm, and a polishing allowance of 0.005 mm is reserved on each side of the lens.

[0042] Figure 3 The image shows the lens after finishing. Its surface has a semi-transparent luster, a surface accuracy PV of 0.98μm, a surface roughness Ra of approximately 60.820nm, and an extremely thin surface damage layer, which meets the requirements for subsequent polishing.

[0043] 5. Lens polishing A conical polishing wheel (i.e., a conformal wool wheel) is constructed by bonding wool material together using a conical-spherical conformal method, with its end shape matching the curved surface shape of the microlenses within the groove. A cerium oxide (CeO2) polishing slurry with a concentration of approximately 20 wt% is prepared, consisting of the following raw materials: 20 wt% cerium oxide with an average particle size of 0.5 μm, 0.5 wt% ammonium polyacrylate (CAS: 9003-3-6), 4.5 wt% nano-silica sol (solid content approximately 30%, particle size range 10~30 nm), and the balance water. The polishing slurry is injected into the groove, ensuring the surface of all microlenses is completely submerged, and the lens surfaces are polished. The conformal wool wheel spindle speed is 10000 rpm, the feed rate is 300 mm / min, the depth of cut is 0.02 mm, and the polishing time for a single lens is 15 min. For each microlens, the wool wheel moves along a spiral or oscillating path from the lens center to the edge to ensure uniform polishing of the entire lens surface.

[0044] After polishing, the workpiece is ultrasonically cleaned with deionized water for 5 minutes to remove residual polishing solution and wool debris, then dehydrated with anhydrous ethanol and dried. The polished lens is shown below. Figure 4 As shown, its surface has a bright and glossy appearance.

[0045] Furthermore, a Taylor-Hopson PGI-8 profilometer, equipped with a diamond stylus with a stylus tip radius of 2μm, was used to measure the profile of the polished microlens. The specific detection method is as follows: (1) Use a standard ball to calibrate the diamond probe.

[0046] (2) Input the technical information of the lens and establish a measurement template. (3) Bring the probe to the top of the lens.

[0047] (4) Run the measurement program. The probe will automatically find the highest point on the top of the lens and move along the generatrix of the lens to obtain the 2D profile.

[0048] (5) Data generation. The measured profile is compared with the theoretical profile to generate the surface error curve (PV value) and the roughness curve (Ra value).

[0049] The results show that after the first processing and polishing, the lens surface accuracy PV is 9.58μm and the surface roughness Ra is 5.104nm.

[0050] 6. Data processing and compensation processing The lens profile curve measured after the first polishing is placed on the same coordinate axis as the theoretical profile. With the lens vertex as the origin, points are taken at equal intervals along the radial direction of the lens (the number of equal points is ≥100). The height difference ΔZ between the measured profile and the theoretical profile at each equal point is calculated. The difference ΔZ is inverted (i.e., -ΔZ) and superimposed on the original theoretical profile to generate a new target profile for processing.

[0051] Import the compensated lens contour data into the machining center, and repeat steps 2 to 5 above, i.e., use PCD tools to perform fine finishing according to the compensated contour, followed by polishing. A schematic diagram of the polished structure is shown below. Figure 5 As shown, where Figure 5 A in the diagram is a top view, and B is a side sectional view. There is a Φ20×4mm groove on it. After processing, a set of microlenses in a circular array are formed in the groove. The diameter of a single lens is 210μm and the radius of curvature R is 1.3mm.

[0052] Furthermore, following the above method, measurements were performed using a Taylor-Hopson PGI-8 profilometer, and the results are as follows: Figures 6-10 As shown, where Figure 6 This is the original measured profile after polishing. Figure 7 This is a graph showing the surface shape error. Figure 8 To obtain a roughness analysis diagram of a small segment (1.440 mm) of the original measured profile using analysis software, Figure 9 This is a roughness analysis diagram of the other end profile (0.1 mm) extracted from the original measured profile. Figure 10 To compensate for the roughness curve of the lens after processing.

[0053] The results show that after compensation processing, the lens surface profile accuracy PV is 1.87μm and the surface roughness Ra is 2.992nm.

[0054] Comparative Example 1: Alumina / Diamond Polishing Fluid This comparative example provides a method for processing an ultra-smooth surface for microlenses within a groove. The difference between this method and Example 1 is that the polishing step in step 5 is different. In this method, an alumina / diamond polishing slurry is used for polishing, while the other steps are the same.

[0055] After finishing in step S4, the lens profile accuracy PV is 0.96 μm, and the surface roughness Ra is approximately 61.383 nm. Step 5, the lens polishing step, is as follows: Using wool material, a conical polishing wheel (i.e., a contoured wool wheel) is formed by bonding together conical balls in a contouring manner, with the end shape matching the curved surface shape of the microlens in the groove.

[0056] The alumina / diamond polishing slurry is prepared by means of the following raw materials: 20wt% alumina with a particle size of 20~100nm, 2wt% diamond with a particle size of 3~6μm, 2wt% dispersant and the balance water.

[0057] Polishing fluid is injected into the grooves until the fluid surface completely submerges all microlens surfaces for polishing. The spindle speed of the contoured wool wheel is 10,000 rpm, the feed rate is 300 mm / min, the depth of cut is 0.02 mm, and the polishing time for a single lens is 15 minutes. For each microlens, the wool wheel moves along a spiral or oscillating path from the lens center to the edge to ensure uniform polishing of the entire lens surface.

[0058] After polishing, ultrasonically clean the workpiece with deionized water for 5 minutes to remove residual polishing liquid and wool debris, then dehydrate with anhydrous ethanol and blow dry.

[0059] The results show that after the first processing and polishing, the lens surface accuracy PV is 18.74μm and the surface roughness Ra is 10.169nm.

[0060] The data is processed according to the method of Example 1 above. Then the compensated lens contour data is imported into the machining center. Steps 4 and 5 above are repeated, that is, PCD tools are used to perform fine finishing according to the compensated contour, and then polishing is performed using alumina / diamond polishing fluid.

[0061] After compensation processing, the lens surface profile was measured using a Taylor-Hopson PGI-8 profiler according to the above method. The measurement results showed that the lens surface profile accuracy PV was 7.28 μm and the surface roughness Ra was 9.545 nm after compensation processing.

[0062] Comparative Example 2: Silica Polishing Fluid This comparative example provides a method for processing an ultra-smooth surface for microlenses within a groove. The difference between this method and Example 1 is that the polishing step in step 5 is different. In this method, a silicon dioxide polishing slurry is used for polishing, while the other steps are the same.

[0063] After finishing in step S4, the lens profile accuracy PV is 0.86 μm, and the surface roughness Ra is approximately 62.022 nm. Step 5, the lens polishing step, is as follows: Using wool material, a conical polishing wheel (i.e., a contoured wool wheel) is formed by bonding together conical balls in a contouring manner, with the end shape matching the curved surface shape of the microlens in the groove.

[0064] The silica polishing slurry is prepared from the following raw materials: 30 wt% colloidal silica and the balance water.

[0065] Polishing fluid is injected into the grooves until the fluid surface completely submerges all microlens surfaces for polishing. The spindle speed of the contoured wool wheel is 10,000 rpm, the feed rate is 300 mm / min, the depth of cut is 0.02 mm, and the polishing time for a single lens is 15 minutes. For each microlens, the wool wheel moves along a spiral or oscillating path from the lens center to the edge to ensure uniform polishing of the entire lens surface.

[0066] After polishing, ultrasonically clean the workpiece with deionized water for 5 minutes to remove residual polishing liquid and wool debris, then dehydrate with anhydrous ethanol and blow dry.

[0067] The results show that after the first processing and polishing, the lens surface accuracy PV is 6.36μm and the surface roughness Ra is 16.465nm.

[0068] The data is processed according to the method of Example 1 above. Then the compensated lens contour data is imported into the machining center. Steps 4 and 5 above are repeated, that is, PCD tools are used to perform fine finishing according to the compensated contour, and then polishing is performed using silica polishing slurry.

[0069] After compensation processing, the lens surface profile was measured using a Taylor-Hopson PGI-8 profiler according to the above method. The measurement results showed that the lens surface profile accuracy PV was 2.13 μm and the surface roughness Ra was 15.81 nm after compensation processing.

[0070] Comparative Example 3: Hand Polishing This comparative example provides a method for fabricating an ultra-smooth surface for microlenses within a groove based on manual polishing, which specifically includes the following:

[0071] 1. Workpiece preparation and clamping Processing object: This experiment takes quartz glass with an outer shape of 28×28×5mm as an example for subsequent processing.

[0072] Cleaning and Clamping: Wipe the surface of the quartz glass blank and the working surface of the vacuum suction cup fixture with a lint-free cloth soaked in anhydrous ethanol (purity ≥99.7%) to remove grease, dust, and other contaminants. After cleaning, dry with clean compressed air to avoid residual liquid affecting the adsorption effect. Then, place the quartz glass blank in the center area of ​​the vacuum suction cup fixture, ensuring the lower surface of the quartz glass blank is in contact with the suction cup sealing ring. Turn on the vacuum system and control the vacuum level to not be lower than -0.08MPa to ensure that the quartz glass blank does not shift or vibrate during processing.

[0073] 2. Rough machining The microlens was rapidly rough-ground using a D2 150# electroplated diamond grinding wheel. The spindle speed of the electroplated diamond grinding wheel was controlled at 18000 rpm, the feed rate at 2000 mm / min, and the depth of cut at 0.05 mm. A machining allowance of 0.1 mm was reserved on each side of the lens. After rough machining, the microlens was initially formed, and its surface was frosted with obvious grinding marks and microcrack layers.

[0074] 3. Lens semi-finishing Replace the electroplated diamond grinding wheel with a D2 1200# electroplated diamond grinding wheel, following the same roughing trajectory as described above, but reduce the feed rate and depth of cut to eliminate coarse cracks caused by rough grinding, and machine to the standard lens shape, reducing surface roughness. Specifically, control the electroplated diamond grinding wheel speed at 20,000 rpm, the feed rate at 500 mm / min, the depth of cut at 0.005 mm, and leave a 0.02 mm finishing allowance on each side of the lens.

[0075] 4. Lens precision machining Finishing was performed using a polycrystalline diamond (PCD) tool with model number D0.8 R0.1, where the tip radius was 0.1 mm and the tool diameter was 0.8 mm.

[0076] During the finishing process, micro-milling or micro-turning is used to refine the microlens along its generatrix. Simultaneously, the PCD tool speed is controlled at 24,000 rpm, the feed rate at 100 mm / min, and the depth of cut at 0.002 mm. A 0.005 mm polishing allowance is reserved on each side of the lens. The finished lens surface exhibits a semi-transparent luster, with a contour accuracy (PV) of 1.07 μm and a surface roughness (Ra) of approximately 61.814 nm. The surface damage layer is extremely thin, meeting the requirements for subsequent polishing.

[0077] 5. Lens polishing A cerium oxide (CeO2) polishing slurry with a concentration of approximately 20 wt% was prepared. The raw materials consisted of: 20 wt% cerium oxide with an average particle size of 0.5 μm, 0.5 wt% ammonium polyacrylate (CAS: 9003-3-6), 4.5 wt% nano-silica sol (solid content approximately 30%, particle size range 10~30 nm), and the balance water. A commercially available fine-pored polyurethane sponge (pore size approximately 0.5~1 mm) was used to adhere the cerium oxide polishing slurry and was used to polish the lens surface by back-and-forth friction. Polishing times were set to 0, 6, 12, 18, or 24 minutes.

[0078] After polishing, ultrasonically clean the workpiece with deionized water for 5 minutes to remove residual polishing liquid, then dehydrate with anhydrous ethanol and blow dry.

[0079] The profile of the polished lens was measured using a Taylor-Hopson PGI-8 profilometer, and the results are shown in the table below: Table 1

[0080] Figures 11-14 Lens images were shown for polishing times of 6, 12, 18, or 24 minutes. The results showed that after 10 minutes of manual polishing, the top of the lens tended to shine, while the sidewalls showed no significant changes. It is speculated that this is because the sponge could not reach the sidewalls and root of the lens, making it impossible to completely polish the lens. Furthermore, the surface accuracy of the polished lens was poor, which was difficult to meet the requirements.

[0081] In summary, this invention proposes a method for machining ultra-smooth surfaces of microlenses within grooves. First, the method involves rough grinding and semi-fine grinding with diamond wheels to form the lens. Then, a PCD tool is used for contour finishing. Finally, a conical spherical contouring wool wheel combined with cerium oxide polishing fluid is used for contour polishing, effectively solving the problem of manual polishing being unable to reach the lens sidewalls and roots due to interference from the groove sidewall structure. Furthermore, this invention introduces an iterative compensation mechanism based on profilometer measurement data. The contour error after polishing is superimposed onto the theoretical machining curve. After 1-3 repeated machining operations, the surface accuracy and roughness can be rapidly improved. Ultimately, a microlens with a surface accuracy PV of 1.87 μm and a surface roughness Ra of 2.992 nm is formed within the quartz groove. This method is significantly superior to traditional manual polishing methods, providing a highly repeatable solution for high-precision, high-consistency machining of groove-embedded micro-optical elements.

[0082] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for processing an ultra-smooth surface for a microlens within a groove, characterized in that, Includes the following steps: S1. The quartz glass is cleaned and coarsely ground to form a groove with microlenses, and then semi-finished with a diamond grinding wheel. S2. Use a polycrystalline diamond tool to finish the semi-finished microlens; S3. Add cerium oxide polishing liquid into the groove, and polish the finely processed microlens with a conical wool wheel to obtain the desired result. The cerium oxide polishing solution contains 15-25 wt% cerium oxide, and the average particle size of the cerium oxide is 0.2-0.8 μm.

2. The method for processing ultra-smooth surfaces according to claim 1, characterized in that, The diameter ratio of the groove to the microlens is 15~30mm:100~300μm; And / or, the depth of the groove is 2~8 mm; And / or, the radius of curvature of the microlens is 0.8~1.5 mm.

3. The method for processing ultra-smooth surfaces according to claim 1, characterized in that, The coarse grinding uses a diamond grinding wheel with diamond particles of 80~110μm in diameter; And / or, the parameters for the rough grinding are set as follows: rotation speed 15000~20000 rpm, feed rate 1800~2200 mm / min, depth of cut 0.02~0.08 mm, and a machining allowance of 0.08~0.12 mm on each side of the lens.

4. The ultra-smooth surface processing method according to claim 3, characterized in that, The semi-finishing process uses a diamond grinding wheel with diamond particles of 5~15μm in diameter; And / or, the parameters for the semi-finishing are set as follows: rotational speed 18000~22000 rpm, feed rate 450~550 mm / min, depth of cut 0.002~0.008 mm, and a finishing allowance of 0.01~0.03 mm on each side of the lens.

5. The method for processing ultra-smooth surfaces according to claim 4, characterized in that, The finishing parameters are set as follows: rotation speed 22000~25000 rpm, feed rate 95~105 mm / min, depth of cut 0.001~0.003mm, and a polishing allowance of 0.004~0.006mm reserved on one side of the lens.

6. The method for processing ultra-smooth surfaces according to claim 5, characterized in that, The polishing parameters are set as follows: spindle speed of 8000~12000 rpm, feed rate of 200~400 mm / min, depth of cut of 0.01~0.03 mm, and polishing time of 10~20 min for a single lens.

7. The method for processing ultra-smooth surfaces according to any one of claims 1 to 6, characterized in that, The polishing process also includes data processing and compensation processing.

8. The method for processing ultra-smooth surfaces according to claim 7, characterized in that, The data processing includes collecting the contour curve of the polished microlens and the theoretical contour curve, placing them on the same coordinate axis, dividing the curve into equal parts, calculating the difference between the division points, and compensating the difference back to the original theoretical curve to generate a new lens processing contour line.

9. The method for processing ultra-smooth surfaces according to claim 8, characterized in that, The compensation process includes repeating the rough grinding, semi-finishing, finishing, and polishing steps based on the lens processing contour.

10. The method for processing ultra-smooth surfaces according to claim 9, characterized in that, The microlens after compensation processing has a roughness Ra < 10 nm and a surface accuracy PV < 15 μm.

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