Large size optical flat uniform polishing process and apparatus

Abstract

The application discloses a large-size optical flat uniform polishing process and equipment, and the large-size optical flat uniform polishing process comprises the following steps: pre-modifying a polishing pad; dividing an optical flat surface into a center area and an edge area, and performing zoned pressure control on the center area and the edge area; supplying polishing liquid to the optical flat surface in a multi-point uniform spraying mode; moving the polishing disc in a compound motion track to polish the optical flat; acquiring real-time surface shape errors of the optical flat, and dynamically adjusting polishing pressure, polishing disc rotating speed and spraying flow according to the real-time surface shape errors. The surface shape precision of the large-size optical flat processed by the method can be stably controlled within λ / 10, the surface uniformity deviation is less than or equal to λ / 20, the edge collapse depth is less than or equal to 0.002 mm, the batch production surface shape consistency is improved by more than 50%, the good product rate is improved from 75% of the traditional process to more than 95%, and the batch application demand of high-precision optical flats for large-aperture industrial, military and scientific research equipment is met.

Description

Technical Field

[0001] This invention relates to the field of optical component processing technology, and in particular to a process and equipment for uniform polishing of large-size optical flats. Background Technology

[0002] Existing large-aperture optical flat plate polishing processes suffer from uneven polishing pad wear and uneven polishing fluid distribution, resulting in inconsistent material removal rates on the optical flat plate surface. This leads to poor surface uniformity of the optical flat plate, such as edge collapse or over-polishing in the middle, which cannot meet the high performance requirements of military, scientific research, and high-end imaging equipment for large-size optical flat plates. Summary of the Invention

[0003] The purpose of this invention is to provide a uniform polishing process for large-size optical flats, so as to solve the problem of poor surface uniformity of large-diameter optical flats produced by existing large-diameter optical flat polishing processes.

[0004] This invention is achieved through the following technical solution:

[0005] A uniform polishing process for large-size optical flat panels includes the following steps:

[0006] S1: Pre-correct the polishing pad;

[0007] S2: Divide the surface of the optical flat plate into a central region and an edge region, and perform zoned pressure control on the central region and the edge region;

[0008] S3: Polishing liquid is supplied to the surface of the optical flat plate using a multi-point uniform spraying method;

[0009] S4: The polishing disc moves in a compound motion trajectory to polish the optical flat plate;

[0010] S5: Obtain the real-time surface shape error of the optical flat plate, and dynamically adjust the polishing pressure, polishing disc speed and spray flow rate based on the real-time surface shape error.

[0011] Furthermore, in step S1, the pre-correction of the polishing pad refers to the compensatory reshaping of the polishing pad according to the target surface shape of the optical plate to counteract its expected uneven wear.

[0012] Furthermore, in step S2, the partitioned pressure control refers to setting different polishing pressures for the central region and the edge region so that the material removal rate of the center and the edge tends to be consistent.

[0013] Furthermore, in step S3, the multi-point uniform spraying refers to configuring multiple nozzles around the optical plate to ensure that the polishing liquid is evenly distributed on the surface of the optical plate.

[0014] Furthermore, in step S4, the composite motion trajectory refers to a combination of planetary motion and oscillating motion.

[0015] To address the problem of poor surface uniformity in large-aperture optical flats produced by existing polishing processes, this invention provides a uniform polishing process for large-size optical flats. Correspondingly, it provides a uniform polishing device for large-size optical flats, including a base, a polishing assembly, a spray assembly, and a control unit. The base is equipped with a polishing table. The polishing assembly includes a polishing disk, a star disk, and a polishing pad. The polishing disk is positioned above the polishing table and can rotate and swing horizontally relative to the base. An off-axis hole is provided on the side of the polishing disk facing the polishing table, offset from the axis of the polishing disk and allowing the star disk to be inserted. The polishing pad is located on the side of the polishing disk facing the polishing table. The spray assembly includes a plurality of spray heads spaced apart circumferentially on the polishing disk. The control unit is mounted on the base and configured to execute the aforementioned uniform polishing process for large-size optical flats.

[0016] Furthermore, the base is provided with a swing arm on one side of the polishing table. The swing arm can swing relative to the base on a horizontal plane. The swing arm is provided with a motor. The polishing disc is provided on the output end of the motor. The polishing disc is driven to rotate horizontally by the motor and is driven to swing horizontally by the swing arm.

[0017] Furthermore, the polishing disc includes an outer support and an inner pressure plate. The upper end of the outer support is connected to the motor, and the lower end is provided with an assembly hole. The inner pressure plate is accommodated in the assembly hole and spaced apart from the wall of the assembly hole. The outer support is provided with fasteners for locking it to the inner pressure plate.

[0018] Furthermore, the spray head is provided with a liquid guide pipe connected to the motor, and the spray head is provided with a liquid adjustment component for adjusting the liquid output.

[0019] Furthermore, the spray head is a flexible tube connected to the liquid guide tube, and the liquid adjustment assembly includes a fixed base and a flow adjustment wheel. The fixed base is inserted through the spray head, and the flow adjustment wheel can move relative to the fixed base to squeeze or release the spray head in order to adjust the liquid output of the spray head.

[0020] The advantages of this technical solution are as follows: by pre-correcting the polishing pad to eliminate wear differences between the edge and center areas, by controlling the pressure in the center and edge areas to make the material removal rate of the center and edge areas more consistent, by uniformly supplying the polishing slurry to ensure uniform distribution of the polishing liquid on the surface of the optical plate, and by moving the polishing disc with a composite motion trajectory to improve the uniformity of material removal and reduce periodic polishing marks, the surface shape accuracy of large-size optical plates processed by this method can be stably controlled within λ / 10, the surface uniformity deviation ≤λ / 20, the edge collapse depth ≤0.002mm, the surface shape consistency of mass production is improved by more than 50%, and the yield rate is increased from 75% of the traditional process to more than 95%, meeting the mass application needs of high-precision optical plates for large-diameter industrial, military, and scientific research equipment. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a uniform polishing process for a large-size optical flat plate according to Embodiment 1 of the present invention;

[0023] Figure 2 This is a three-dimensional embodiment of a large-size optical flat uniform polishing device according to Embodiment 2 of the present invention. Figure 1 ;

[0024] Figure 3 yes Figure 2 A magnified view of a section at point A in the middle;

[0025] Figure 4 This is a three-dimensional embodiment of a large-size optical flat uniform polishing device according to Embodiment 2 of the present invention. Figure 2 ;

[0026] Figure 5 yes Figure 4 A magnified view of a section at point B in the middle. Detailed Implementation

[0027] 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, and 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.

[0028] Example 1: As Figure 1As shown, this uniform polishing process for large-size optical flat panels includes the following steps:

[0029] S1: Pre-correct the polishing pad;

[0030] S2: Divide the surface of the optical flat plate into a central region and an edge region, and perform zoned pressure control on the central region and the edge region;

[0031] S3: Polishing liquid is supplied to the surface of the optical flat plate using a multi-point uniform spraying method;

[0032] S4: The polishing disc moves in a compound motion trajectory to polish the optical flat plate;

[0033] S5: Obtain the real-time surface shape error of the optical flat plate, and dynamically adjust the polishing pressure, polishing disc speed and spray flow rate based on the real-time surface shape error.

[0034] In step S1, the pre-correction of the polishing pad refers to the compensatory reshaping of the polishing pad according to the target surface shape of the optical flat plate to offset its expected uneven wear. Step S1 reduces surface shape error from the source by pre-correcting the surface shape of the polishing pad in advance to compensate for the wear difference between the edge area and the center area during the polishing process.

[0035] In step S2, zoned pressure control refers to setting different polishing pressures for the central and edge regions to make the material removal rates of the center and edges more consistent, thereby suppressing surface unevenness. Step S2 sets differentiated polishing pressures for the center and edge regions of the optical flat plate to balance the material removal rates of the center and edge regions and avoid over-polishing of the center or under-polishing of the edges.

[0036] In step S3, multi-point uniform spraying refers to configuring multiple nozzles around the periphery of the optical plate to ensure that the polishing slurry is evenly distributed on the surface of the optical plate. Step S3 adopts a multi-nozzle annular spraying design to ensure that the polishing slurry is evenly distributed across the entire surface of the optical plate, eliminating uneven polishing caused by local slurry shortages.

[0037] In step S4, the composite motion trajectory refers to the combination of planetary motion and oscillating motion. Step S4 optimizes the motion trajectory of the polishing disc and the workpiece, improves the uniformity of material removal, and reduces periodic polishing marks.

[0038] Step S5 achieves closed-loop process control by dynamically adjusting parameters such as polishing pressure and rotation speed during real-time detection of surface shape errors during the polishing process.

[0039] In summary, the embodiments of the present invention provide a uniform polishing process for large-size optical flats to solve the problem of poor surface uniformity in large-diameter optical flats produced by existing polishing processes. This is mainly achieved by pre-correcting the polishing pad to eliminate wear differences between the edge and center regions, controlling the pressure in separate zones between the center and edge regions to ensure consistent material removal rates, uniformly distributing the polishing slurry across the optical flat surface through uniform slurry supply, and improving the uniformity of material removal and reducing periodic polishing marks by moving the polishing disc along a composite motion trajectory. Therefore, large-size optical flats processed using this method possess the following characteristics:

[0040] 1. High surface accuracy: The surface accuracy of large-size optical flat plates is stably controlled within λ / 10, such as λ=632.8nm;

[0041] 2. High uniformity: Surface uniformity deviation ≤ λ / 20;

[0042] 3. High edge quality (no edge collapse): Edge collapse depth ≤ 0.002mm;

[0043] 4. High consistency in mass production: The consistency of surface shape in mass production is improved by more than 50%;

[0044] 5. High yield rate: The yield rate has been increased from 75% with traditional processes to over 95%.

[0045] To further illustrate the present invention, the polishing of a fused silica optical plate with a diameter of 100 mm using the above method is described below, with the steps and specific parameters as follows:

[0046] Step S1: Based on the target surface shape of the optical flat plate, perform surface shape pre-correction on the polyurethane polishing pad to compensate for edge wear differences;

[0047] Step S2: Divide the surface of the optical flat plate into a central region and an edge region, and perform zoned pressure control on the central region and the edge region. Set the polishing pressure of the central region to 0.10MPa and the edge region to 0.14MPa.

[0048] Step S3: Use an 8-nozzle annular spray system, and control the polishing fluid flow rate at 6L / min;

[0049] Step S4: The polishing disc moves along a combined planetary and oscillating motion trajectory, with a rotation speed of 180 r / min and an oscillation frequency of 15 times / min;

[0050] Step S5: During the polishing process, the surface shape error is detected in real time by an interferometer, and the pressure and speed are dynamically adjusted. The final surface shape accuracy PV value is λ / 12, the surface uniformity deviation is λ / 25, the edge collapse depth is 0.0015mm, and the yield rate reaches 98%.

[0051] To further illustrate the present invention, the above method is used to polish an optical glass plate with a diameter of 300 mm. The steps and specific parameters are as follows:

[0052] Step S1: Based on the target surface shape of the optical flat plate, perform adaptation pre-correction on the polishing pad to compensate for the wear difference between the center and the edge;

[0053] Step S2: Divide the surface of the optical flat plate into a central region and an edge region, and perform zoned pressure control on the central region and the edge region. Set the polishing pressure of the central region to 0.08MPa and the edge region to 0.12MPa.

[0054] Step S3: Use a 6-nozzle annular spray system, and control the polishing fluid flow rate at 4L / min;

[0055] Step S4: The polishing disc moves along a combined planetary and oscillating motion trajectory, with a rotation speed of 150 r / min and an oscillation frequency of 12 times / min;

[0056] Step S5: Real-time detection of surface shape error and dynamic adjustment of parameters. The final surface shape accuracy PV value = λ / 11, surface uniformity deviation = λ / 22, edge collapse depth = 0.0012mm, and the yield rate reaches 97%.

[0057] Example 2: As Figure 2-5 As shown, the large-size optical flat uniform polishing equipment includes a base 1, a polishing assembly 2, a spray assembly 3, and a control unit (not shown in the figure). The base 1 is provided with a polishing table 101. The polishing assembly 2 includes a polishing disk 201, a star disk 202, and a polishing pad (not shown in the figure). The polishing disk 201 is located above the polishing table 101 and can rotate and swing horizontally relative to the base 1. The side of the polishing disk 201 facing the polishing table 101 is provided with an off-axis hole 200. The off-axis hole 200 is off-center from the axis of the polishing disk 201 and allows the star disk 202 to be inserted. The polishing pad is located on the side of the polishing disk 201 facing the polishing table 101. The spray assembly 3 includes a plurality of spray heads 301 spaced apart around the polishing disk 201. The control unit (not shown in the figure) is located on the base 1 and is configured to perform the above-mentioned large-size optical flat uniform polishing process.

[0058] When the polishing disk 201 rotates horizontally around its axis, it drives the star disk 202 to rotate around its axis, and simultaneously drives the star disk 202 to rotate horizontally around the axis of the polishing disk 201; when the polishing disk 201 oscillates horizontally, it drives the star disk 202 to oscillate horizontally. The above configuration allows the polishing disk 201 to move in a compound motion trajectory.

[0059] Specifically, the base 1 has a swing arm 102 on one side of the polishing table 101. The swing arm 102 can swing relative to the base 1 on the horizontal plane. The swing arm 102 is equipped with a motor 103. The output end of the motor 103 is equipped with a polishing disc 201. The polishing disc 201 is driven to rotate horizontally by the motor 103 and is driven to swing horizontally by the swing arm 102.

[0060] Specifically, the polishing disc 201 includes an outer support 204 and an inner pressure plate 205. The upper end of the outer support 204 is connected to the motor 103, and the lower end is provided with an assembly hole 206. The inner pressure plate 205 is accommodated in the assembly hole 206 and is spaced apart from the hole wall of the assembly hole 206. The outer support 204 is provided with fasteners (not shown in the figure) that lock it onto the inner pressure plate 205. The fasteners are bolts.

[0061] Specifically, the spray head 301 is provided with a liquid guide pipe 302 connected to the motor 103, and the spray head 301 is provided with a liquid adjustment component 303 for adjusting the liquid output.

[0062] Specifically, the spray head 301 is a flexible tube connected to the liquid guide tube 302. The liquid adjustment assembly 303 includes a fixed seat 304 and a flow adjustment wheel 305. The fixed seat 304 is installed on the spray head 301. The flow adjustment wheel 305 can move relative to the fixed seat 304 to squeeze or release the spray head 301 in order to adjust the liquid output of the spray head 301.

[0063] It should be understood that the terms "first," "second," etc., are used in this invention to describe various information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this invention, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information. In addition, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0064] The above description provides one or more embodiments in conjunction with specific content, and does not imply that the specific implementation of the present invention is limited to these descriptions. Any methods or structures that are similar to or identical to those of the present invention, or any technical deductions or substitutions made based on the concept of the present invention, should be considered as protected by the present invention.

Claims

1. A uniform polishing process for large-size optical flat panels, characterized in that, Includes the following steps: S1: Pre-correct the polishing pad; S2: Divide the surface of the optical flat plate into a central region and an edge region, and perform zoned pressure control on the central region and the edge region; S3: Polishing liquid is supplied to the surface of the optical flat plate using a multi-point uniform spraying method; S4: The polishing disc moves in a compound motion trajectory to polish the optical flat plate; S5: Obtain the real-time surface shape error of the optical flat plate, and dynamically adjust the polishing pressure, polishing disc speed and spray flow rate based on the real-time surface shape error.

2. The uniform polishing process for large-size optical flat panels according to claim 1, characterized in that, In step S1, the pre-correction of the polishing pad refers to the compensatory reshaping of the polishing pad according to the target surface shape of the optical plate to counteract its expected uneven wear.

3. The uniform polishing process for large-size optical flat panels according to claim 1, characterized in that, In step S2, the partitioned pressure control refers to setting different polishing pressures for the central region and the edge region so that the material removal rate of the center and the edge tends to be consistent.

4. The uniform polishing process for large-size optical flat panels according to claim 1, characterized in that, In step S3, the multi-point uniform spraying refers to arranging multiple nozzles around the optical plate to make the polishing liquid evenly distributed on the surface of the optical plate.

5. The uniform polishing process for large-size optical flat panels according to claim 1, characterized in that, In step S4, the composite motion trajectory refers to the combination of planetary motion and oscillating motion.

6. A large-size optical flat plate uniform polishing device, characterized in that, The device includes a base, a polishing assembly, a spray assembly, and a control unit. The base has a polishing table. The polishing assembly includes a polishing disc, a star disk, and a polishing pad. The polishing disc is positioned above the polishing table and is capable of horizontal rotation and horizontal swing relative to the base. An off-axis hole is provided on the side of the polishing disc facing the polishing table, offset from the axis of the polishing disc and allowing the star disk to be inserted. The polishing pad is located on the side of the polishing disc facing the polishing table. The spray assembly includes a plurality of spray heads spaced apart circumferentially on the polishing disc. The control unit is located on the base and configured to perform a uniform polishing process for a large-size optical flat panel as described in any one of claims 1 to 5.

7. A large-size optical flat plate uniform polishing device according to claim 6, characterized in that, The base has a swing arm on one side of the polishing table. The swing arm can swing relative to the base on a horizontal plane. The swing arm is equipped with a motor. The polishing disc is located on the output end of the motor. The polishing disc is driven to rotate horizontally by the motor and to swing horizontally by the swing arm.

8. The large-size optical flat uniform polishing equipment according to claim 7, characterized in that, The polishing disc includes an outer support and an inner pressure plate. The upper end of the outer support is connected to the motor, and the lower end is provided with an assembly hole. The inner pressure plate is accommodated in the assembly hole and spaced apart from the wall of the assembly hole. The outer support is provided with fasteners to lock it to the inner pressure plate.

9. A large-size optical flat plate uniform polishing device according to claim 7, characterized in that, The spray head is equipped with a liquid guide tube connected to the motor, and the spray head is equipped with a liquid adjustment component to adjust the liquid output.

10. A large-size optical flat plate uniform polishing device according to claim 9, characterized in that, The spray head is a flexible tube connected to the liquid guide tube. The liquid adjustment assembly includes a fixed base and a flow adjustment wheel. The fixed base is inserted through the spray head, and the flow adjustment wheel can move relative to the fixed base to squeeze or release the spray head to adjust the liquid output of the spray head.

Images