Method for machining calcium fluoride optical components

Abstract

The application relates to the technical field of optical part processing, and provides a processing method of a calcium fluoride optical part, the calcium fluoride optical part comprising a first face and a second face opposite to each other, and the processing method comprises the following steps: chamfering and preliminarily polishing the calcium fluoride optical part to obtain a to-be-preliminary-polished workpiece; using rosin wax to plate the first face of the to-be-preliminary-polished workpiece, grinding and polishing the second face to obtain a preliminary-polished workpiece; using a glue spot to plate the second face of the preliminary-polished workpiece, grinding and polishing the first face; using optical glue to plate the first face of the preliminary-polished workpiece, grinding and polishing the second face to obtain a secondary-polished workpiece; using a glue spot to plate the second face of the secondary-polished workpiece, and repairing and polishing the first face; using a slotted damping cloth to precisely polish the first face and the second face to obtain a final-polished workpiece; and detecting indexes of the final-polished workpiece. Different plating processes are used in a targeted manner, so that the polishing quality of the calcium fluoride optical part after processing is improved, and the smoothness of the calcium fluoride optical part is improved.

Description

Technical Field

[0001] This application relates to the field of optical component processing technology, and more specifically, to a method for processing calcium fluoride optical components. Background Technology

[0002] Traditional optical processing methods, which only use a wax-sealing plate for processing both sides, cannot effectively control the parallelism and surface shape of the product. Using a wax-sealing plate and a 417 sealing plate also cannot effectively control the surface shape of the product. This invention uses rosin wax, rosin glue dots, and gloss glue for plate application, which can effectively control the surface shape and parallelism of the product. Finally, damping cloth is used for fine finishing, solving the processing problems of surface shape, parallelism, roughness, and smoothness when processing calcium fluoride products.

[0003] Currently, most domestic processing of CaF2 (calcium fluoride) products employs methods such as chemical mechanical polishing, consolidated abrasive polishing, magnetorheological polishing, and ion beam polishing, which can achieve good surface quality and morphology. Among these methods, chemical mechanical polishing mainly uses the frictional force generated by the rotation of the polishing disc to rotate the workpiece. A polishing slurry containing abrasive particles and chemical components is then delivered to the polishing pad. Through chemical action, the workpiece surface is softened and eroded. The softened layer is then removed by the mechanical friction of the abrasive particles in the polishing slurry, achieving a global planarization effect.

[0004] When using chemical mechanical polishing, both sides of calcium fluoride optical parts need to be polished separately. However, the processing quality is affected by many factors. In particular, for calcium fluoride optical parts with high polishing quality requirements, traditional polishing methods and polishing tools can no longer meet the requirements of high polishing quality, which will affect the surface finish of the processed calcium fluoride optical parts during chemical mechanical polishing.

[0005] Therefore, existing technologies still need improvement and development. Summary of the Invention

[0006] The purpose of this application is to propose a processing method for calcium fluoride optical parts, thereby improving the surface finish of the processed calcium fluoride optical parts.

[0007] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for processing a calcium fluoride optical component, wherein the calcium fluoride optical component includes a first surface and a second surface opposite to each other, and the processing method includes:

[0008] Step S1: Chamfer and pre-polish the calcium fluoride optical component to obtain a workpiece to be pre-polished with a predetermined surface shape.

[0009] Step S2: Use rosin wax to polish the first surface of the workpiece to be polished, and then sand and polish the second surface to obtain a workpiece with a predetermined surface shape.

[0010] Step S3: Apply adhesive dots to the second surface of the initially polished workpiece, then sand and polish the first surface;

[0011] Step S4: Apply the adhesive to the first surface of the initially polished workpiece, then sand and polish the second surface to obtain a second-polished workpiece with a predetermined surface shape.

[0012] Step S5: Apply adhesive to the second surface of the workpiece as described in the first polishing step, and then re-polish the first surface.

[0013] Step S6: Refine the surface shape of the first and second surfaces using grooved damping cloth to obtain the final polished workpiece;

[0014] Step S7: Perform index testing on the final polished workpiece to meet product requirements.

[0015] Furthermore, in step S1, a cast iron mold is used in conjunction with diamond abrasive to chamfer the calcium fluoride optical component, and a polyurethane polishing mold is used to polish the chamfered edges of the calcium fluoride optical component to achieve preliminary polishing.

[0016] Further, step S2 includes:

[0017] Heat the aluminum pan and apply rosin wax to the upper surface of the pan. Place the workpiece to be initially polished onto the upper surface of the aluminum pan. Cool the aluminum pan and apply waterproof adhesive to the first surface of the workpiece to be initially polished.

[0018] The second surface is sanded using a single-axis sander;

[0019] The second surface is polished using a flat low-profile polishing machine, wherein the polishing plate of the flat low-profile polishing machine is an asphalt rubber plate;

[0020] Heat the aluminum disc and remove the initially polished workpiece;

[0021] The initial polished workpiece was soaked in Polyac to remove rosin wax;

[0022] The initial polished workpiece was soaked in pure acetone to remove the waterproof adhesive.

[0023] In some implementations, step S3 includes:

[0024] Apply waterproof adhesive to the second surface, heat the initial polished workpiece and apply adhesive dots to the second surface, then attach the second surface to the aluminum disc through the adhesive dots.

[0025] The first surface was sanded using a single-axis sander;

[0026] The first surface is polished using a flat low-profile polishing machine for a first time and a first thickness. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate.

[0027] Apply waterproof adhesive to the first surface, freeze the aluminum tray, remove the initially polished workpiece, soak it in pure acetone to remove the adhesive, and then soak it in a mixed solution.

[0028] Further, step S4 includes:

[0029] Apply waterproof adhesive to the first surface and then attach the first surface of the initially polished workpiece to the adhesive tray.

[0030] The second surface is sanded using a flat single-axis sander;

[0031] The second surface is polished using a flat low-profile polishing machine for a duration of one time. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate.

[0032] A support member with a thickness greater than that of the initial polished workpiece is symmetrically bonded to the edge of the polishing pad. The polishing pad is then inverted to suspend the initial polished workpiece in the air. The initial polished workpiece is then soaked in pure acetone until it detaches from the polishing pad, thereby obtaining a secondary polished workpiece with a predetermined surface shape.

[0033] In some implementations, step S5 includes:

[0034] Apply waterproof adhesive to the second surface, heat the workpiece for secondary polishing, and apply adhesive dots to the second surface. Then, attach the second surface to the aluminum disc through the adhesive dots.

[0035] The first surface is polished using a flat low-profile polishing machine. The polishing time is the second time, and the polishing thickness is the second thickness. The second time is less than the first time, and the second thickness is less than the first thickness. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate.

[0036] Apply waterproof adhesive to the first surface, freeze the aluminum tray, remove the second-polished workpiece, soak it in pure acetone to remove the adhesive, and then soak it in a mixed solution.

[0037] Further, in step S6, a pendulum wheel is used to perform double-sided finishing on the secondary polished workpiece. The pendulum wheel has a through hole for placing the secondary polished workpiece, and a drive shaft for rotating the pendulum wheel is connected to the pendulum wheel. The slotted damping cloth has staggered partition grooves. Step S6 includes:

[0038] The grooved damping cloth is placed on the lower plate of the double-sided polishing machine, and the final polishing liquid is placed in it so that the final polishing liquid immerses the dividing groove.

[0039] Apply waterproof adhesive to the second surface, place the workpiece into the through hole, place the penetrating wheel on the grooved damping cloth on the lower plate of the double-sided polishing machine, start the drive shaft, and clean the waterproof adhesive after fine polishing the first surface.

[0040] Apply waterproof adhesive to the first surface, place the workpiece into the through hole, place the walkie-talkie on the polishing pad of the double-sided polishing machine, start the drive shaft, and after fine polishing the second surface, clean the waterproof adhesive.

[0041] In some implementations, step S7 includes:

[0042] The surface shape, roughness, smoothness, dimensions, and parallelism of the final polished workpiece are inspected.

[0043] Furthermore, when using the aforementioned flat low-profile polishing machine for polishing, the polishing auxiliary materials include 50nm diamond powder and deionized water, with the pH range adjusted to 9-10. Before polishing, the polishing auxiliary materials are ultrasonically sonicated for 10 minutes.

[0044] In some embodiments, when polishing is performed using the flat low-profile polishing machine, the oscillation speed of the polishing plate is 3-4 rad / min, the oscillation amplitude of the polishing plate is 11, the rotational speed of the drive shaft is 30-35 rad / min, the controlled temperature is 25-28°C, and the first time is 20 hours.

[0045] The beneficial effects of the processing method for calcium fluoride optical parts provided in this application are at least as follows: based on the actual needs of each polishing step and the characteristics of the mounting process, different mounting processes are adopted in a targeted manner. While ensuring the positioning requirements of each polishing, the first and second surfaces of the calcium fluoride optical parts can also be protected, thereby improving the overall polishing quality of the processed calcium fluoride optical parts and enhancing the surface finish of the calcium fluoride optical parts.

[0046] In this embodiment, grooved damping cloth is used as the polishing pad during fine polishing. Compared with conventional damping cloth, grooved damping cloth is less prone to collapse and deformation, thus increasing the time for a single fine polishing session. This greatly improves the effect of fine polishing and better removes the fine scratches generated after classical polishing. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0048] Figure 1A flowchart illustrating the processing method of the calcium fluoride optical component provided in the embodiments of this application;

[0049] Figure 2 A perspective view of a calcium fluoride optical component provided in an embodiment of this application;

[0050] Figure 3 A perspective view of a calcium fluoride optical component after adhesive dots have been applied, as provided in an embodiment of this application.

[0051] Figure 4 A schematic diagram of the structure of the calcium fluoride optical component provided in the embodiments of this application after it is mounted on a disk with adhesive dots;

[0052] Figure 5 A schematic diagram of the structure of the calcium fluoride optical component provided in the embodiments of this application after being mounted on the optical adhesive;

[0053] Figure 6 This is a schematic diagram of the structure of the swivel wheel and the grooved damping cloth used for polishing, as provided in the embodiments of this application.

[0054] Figure 7 for Figure 6 A three-dimensional view from another angle.

[0055] The following are the labeling elements in the figure:

[0056] 1. Calcium fluoride optical components; 11. First side; 12. Second side;

[0057] 2. Grooved damping cloth; 21. Dividing groove;

[0058] 3. Aluminum disc;

[0059] 4. Axle wheel; 41. Through hole; 42. Drive shaft;

[0060] 5. Glossy film disc. Detailed Implementation

[0061] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0062] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it may be directly or indirectly located on that other component. When a component is referred to as "connected to" another component, it may be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positions based on the accompanying drawings, and are for ease of description only, and should not be construed as limiting the technical solution. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly defined.

[0063] The following describes, with reference to the accompanying drawings, a method for processing calcium fluoride optical components 1 according to an embodiment of this application.

[0064] Please see Figure 1 , Figure 1 A flowchart illustrating the processing method of the calcium fluoride optical component 1 of this application is shown.

[0065] Among them, see Figure 2 The calcium fluoride optical component 1 includes a first surface 11 and a second surface 12 facing each other, and the processing method includes:

[0066] Step S1: Chamfer and pre-polish the calcium fluoride optical component 1 to obtain a workpiece to be initially polished with a predetermined surface shape.

[0067] Step S2: Apply rosin wax to the first surface 11 of the workpiece to be initially polished, sand and polish the second surface 12 to obtain the initial polished workpiece with the predetermined surface shape.

[0068] Step S3: Apply adhesive to the second surface 12 of the workpiece for initial polishing, and then sand and polish the first surface 11.

[0069] Step S4: Apply a light adhesive to the first surface 11 of the workpiece for initial polishing, and then sand and polish the second surface 12 to obtain a second-polished workpiece with a predetermined surface shape.

[0070] Step S5: Apply adhesive to the second surface 12 of the workpiece for the first polishing, and then re-polish the first surface 11.

[0071] Step S6: Use the slotted damping cloth 2 to refine the surface shape of the first surface 11 and the second surface 12 to obtain the final polished workpiece.

[0072] Step S7: Perform index testing on the final polished workpiece to meet product requirements.

[0073] It should be noted that when using chemical mechanical polishing, the first surface 11 and the second surface 12 of the calcium fluoride optical component 1 need to be polished separately. For calcium fluoride optical components 1 with high polishing quality requirements, such as some calcium fluoride optical components 1 used in the field of high-power lasers, the surface finish is very high and processing marks are not allowed. Traditional polishing methods and polishing tools can no longer meet the requirements of high polishing quality and it is difficult to meet the surface finish requirements.

[0074] In this embodiment, the calcium fluoride optical component 1 is polished in steps, and each polishing step adopts a targeted mounting method, namely, rosin wax mounting, adhesive dot mounting, and light adhesive mounting. At the same time, rework polishing is performed and the surface shape is refined by grooved damping cloth 2, which can significantly improve the polishing quality of the processed calcium fluoride optical component 1 and improve the surface finish of the calcium fluoride optical component 1.

[0075] Specifically, in step S2, which is when the workpiece to be initially polished is polished to a bright finish, the purpose of this step is to remove the damaged layer from the blank processing and to initially adjust the parallelism. Therefore, the method of applying rosin wax to the plate is selected. Rosin wax refers to a mixture of rosin and wax, which facilitates the loading and unloading of calcium fluoride optical parts 1 and saves costs.

[0076] When performing step S3, which is the initial polishing of the workpiece, the purpose of this step is to obtain a high plane quality. There are two main reasons for choosing the glue dot plate: First, the surface shape requirement is high, and the glue dot plate is more likely to polish the calcium fluoride optical parts 1 with qualified surface shape. Second, the subsequent process requires coating. After coating experiments to determine the amount of change, the surface shape of the coating substrate is required to be concave. The glue dots are elastic and are easier to polish the concave shape.

[0077] In step S4, which is also a job-level polishing of the initial polished workpiece, the purpose of this step is to obtain a high plane quality. Traditional wax sealing on the plate cannot guarantee parallelism. Secondly, when the size of the calcium fluoride optical part 1 is large, if 417 optical adhesive is used for bonding, the pull force of the adhesive is mainly concentrated on the outer diameter, which will cause the surface shape to be compromised during the polishing process. Furthermore, the amount of change of a single part after being removed from the plate will be different from that on the plate, increasing the difficulty of control. Therefore, the method of using optical adhesive on the plate is adopted for processing, which can ensure parallelism while also controlling the surface shape well.

[0078] When performing step S5, which is the re-polishing of the first surface 11 of the workpiece after the second polishing, both the first surface 11 and the second surface 12 have already undergone operational polishing and have good surface quality. The re-polishing is to correct the surface of the first surface 11 on the adhesive plate. After multiple processing experiments, it was found that since the adhesive is bonded by the attraction between molecules, and calcium fluoride is prone to cleavage, the bonding surface will have defects, i.e., spots, after the adhesive is soaked in the plate, which will greatly affect the smoothness. Therefore, it is necessary to re-polish the first surface 11 with adhesive dots to reduce the risk of leaving marks on the second surface 12.

[0079] Therefore, before fine polishing, different mounting processes are adopted in a targeted manner according to the actual needs of each polishing step and the characteristics of the mounting process. While ensuring the positioning requirements of each polishing, the first surface 11 and the second surface 12 of the calcium fluoride optical component 1 can also be protected, thereby improving the overall polishing quality of the calcium fluoride optical component 1 after processing and improving the surface finish of the calcium fluoride optical component 1.

[0080] Meanwhile, grooved damping cloth 2 was chosen as the polishing pad for fine polishing because for products polished using traditional methods, especially brittle materials like calcium fluoride, processing marks are left after processing. These marks are not visible under ordinary light sources and can only be seen under Leica lamps or high-intensity lights. For lenses used in high-power laser applications, these processing marks can affect their lifespan, so they need to be removed. Experiments have shown that damping cloth is softer than asphalt rubber sheets and can effectively remove the fine scratches produced after traditional polishing.

[0081] Furthermore, if conventional damping cloth is used for finishing, the time spent will be too long, which will cause changes in the window surface shape and affect the quality of the finished product. Therefore, the time for each finishing polishing session must be reduced, and the finishing time for one side must be controlled within 10 minutes. In this embodiment, the polishing pad uses grooved damping cloth 2 placed underneath. Compared with conventional damping cloth, grooved damping cloth 2 is less prone to collapse and deformation, so the time for each finishing polishing session can be increased, and the finishing time for one side can be controlled to be more than 30 minutes. This greatly improves the finishing polishing effect and better removes the fine scratches generated after classical polishing.

[0082] In some embodiments, in step S1, a cast iron mold is used in conjunction with diamond abrasive to chamfer the calcium fluoride optical component 1, and a polyurethane polishing mold is used to polish the chamfered edges of the calcium fluoride optical component 1 to achieve preliminary polishing, so that there are no cracks at the chamfered edges and no damage to the outer diameter.

[0083] Further, step S2 includes:

[0084] Step S21: Heat the aluminum plate 3 and apply rosin wax to the upper surface of the aluminum plate 3. Place the workpiece to be initially polished on the upper surface of the aluminum plate 3. Cool the aluminum plate 3 and apply waterproof adhesive to the first surface 11 of the workpiece to be initially polished. The purpose of the waterproof adhesive is to protect the first surface 11.

[0085] Step S22: Use a single-axis sander to sand the second surface 12. This step has two main purposes: first, to reduce the size and remove the damaged layer from the blank processing; second, to control the parallelism so that the parallelism can be controlled during the subsequent polishing process.

[0086] Step S23: Polish the second surface 12 using a flat low-profile polishing machine. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate. The purpose is to remove the damaged layer while ensuring that the surface shape of the rough and shiny surface will not change when processing the other side. In addition, unlike fine polishing, this step requires a greater degree of polishing to the processed surface. Therefore, an asphalt rubber plate with greater hardness is selected as the polishing plate.

[0087] Step S24: Heat aluminum plate 3, remove the workpiece to be initially polished, soak the workpiece to be initially polished with Polyac to remove rosin wax, soak the workpiece to be initially polished with pure acetone to remove waterproof glue, so as to obtain the initial polished workpiece with the predetermined surface shape.

[0088] The lower plate is heated, and the temperature is slowly increased to melt the rosin wax. Then, the calcium fluoride optical component 1 can be removed and arranged neatly with the glossy side facing up. Next, it is soaked in polyacrylamide for at least half an hour to fully dissolve the rosin wax. Then, it is soaked in pure acetone to remove the waterproof adhesive. After rinsing off the surface impurities, it is transferred to a clean mixture. After wiping and cleaning, it is dried with a clean cotton cloth. During the operation, it is necessary to protect the calcium fluoride optical component 1 from scratches.

[0089] In some implementations, step S3 includes:

[0090] Step S31: See Figure 4 Waterproof adhesive is applied to the second surface 12, the workpiece is heated and the adhesive dots are bonded to the second surface 12, and the second surface 12 is attached to the aluminum disc 3 through the adhesive dots. The purpose of the waterproof adhesive is to protect the second surface 12.

[0091] Step S32: Use a single-axis sander to sand the first surface 11. This step also has two purposes: first, to reduce the size and remove the damaged layer during the blank processing; second, to control the parallelism, so as to facilitate the control of parallelism during the subsequent polishing process.

[0092] Step S33: Polish the first surface 11 using a flat low-profile polishing machine. The polishing time is the first time, the polishing thickness is the first thickness, and the polishing plate of the flat low-profile polishing machine is an asphalt rubber plate.

[0093] Step S34: Apply waterproof adhesive to the first surface 11, freeze the aluminum tray 3, remove the initially polished workpiece, soak it in pure acetone to remove the adhesive, and then soak it in the mixed solution. The adhesive dots on the upper tray correspond to the lower tray. After applying protective adhesive, freeze it in the refrigerator for at least 2 hours. Place the workpiece evenly on the upper tray with the polished surface facing up to prevent bumps and scratches. Soak it in clean pure acetone to remove the adhesive and gently rinse it, then soak it in the mixed solution. Wipe it clean with a clean cotton cloth to avoid creating a smooth finish in auxiliary processes.

[0094] In some implementations, step S4 includes:

[0095] Step S41: Apply waterproof adhesive to the first surface 11, see [reference]. Figure 5 The first surface 11 of the initially polished workpiece is glued to the glue tray 5.

[0096] Step S42: Use a flat single-axis sander to sand the second surface 12.

[0097] Step S43: Polish the second surface 12 using a flat low-profile polishing machine for a duration of one hour. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate.

[0098] Step S44: Symmetrically bond support members with a thickness greater than that of the workpiece to the edge of the polishing tray 5, invert the polishing tray 5 to suspend the workpiece, and soak the workpiece in pure acetone until it detaches from the polishing tray 5.

[0099] Normally, the mounting plate for calcium fluoride is made by using a blade and a blowtorch to heat it. However, due to the brittle and easily cleaved nature of calcium fluoride, both of these methods would cause irreversible damage. Therefore, acetone soaking was chosen. A cotton cloth is placed at the bottom of the basin, and supports higher than the parts are symmetrically attached at three points along the edge of the plate. The plate is then inverted onto the cotton cloth at the bottom of the basin, and pure acetone is poured over it to completely submerge the plate. The parts detach by their own weight without any external force. The soaking time is uncertain and may require 24-48 hours. After soaking and rinsing, the parts are gently wiped clean with a clean mixture and a cotton cloth.

[0100] In some implementations, step S5 includes:

[0101] Step S51: Apply waterproof adhesive to the second surface 12, heat the workpiece for secondary polishing and apply adhesive dots to the second surface 12, and attach the second surface 12 to the aluminum disc 3 through the adhesive dots.

[0102] Step S52: Polish the first surface 11 using a flat low-profile polishing machine. The polishing time is the second time, and the polishing thickness is the second thickness. The second time is shorter than the first time, and the second thickness is shorter than the first thickness. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate. Because if the polishing time is too long, the rubber dots are elastic, and if not properly controlled, it will cause parallel deviation. Therefore, it is necessary to remove the dots while ensuring parallelism. In other words, when performing rework polishing, a shorter polishing time and a smaller size can be selected.

[0103] Step S53: Apply waterproof adhesive to the first surface 11, freeze the aluminum tray 3, remove the workpiece to be polished, soak it in pure acetone to remove the adhesive, and then soak it in the mixed solution. Specifically, use a frozen lower tray, apply protective adhesive, freeze in a refrigerator for at least 2 hours, place the polished surfaces evenly on top to prevent bumps and scratches, soak it in clean pure acetone to remove the adhesive and gently rinse it, then soak it in the mixed solution, and finally wipe it clean with a clean cotton cloth to avoid producing a smooth finish in auxiliary processes.

[0104] Further, in step S6, refer to Figure 6 and Figure 7 The workpiece is subjected to double-sided finishing using a penetrating wheel 4. The penetrating wheel 4 has a through hole 41 for placing the workpiece, and a drive shaft 42 for rotating the penetrating wheel 4 is connected to the penetrating wheel 4. The slotted damping cloth 2 has staggered partition grooves 21. Step S6 includes:

[0105] Step S61: Place the grooved damping cloth 2 on the lower plate of the double-sided polishing machine, and put in the final polishing liquid so that the final polishing liquid immerses the partition groove 21.

[0106] Step S62: Apply waterproof adhesive to the second surface 12, place the workpiece to be polished into the through hole 41, place the walking wheel 4 on the grooved damping cloth 2 on the lower plate of the double-sided polishing machine, start the drive shaft 42, and clean the waterproof adhesive after fine polishing the first surface 11.

[0107] Step S63: Apply waterproof adhesive to the first surface 11, place the workpiece to be polished into the through hole 41, place the walking wheel 4 onto the polishing pad on the lower plate of the double-sided polishing machine, start the drive shaft 42, and clean the waterproof adhesive after fine polishing the second surface 12.

[0108] It should be noted that, for reference Figure 6 The dividing grooves 21 are arranged in parallel rows and columns, vertically intersecting each other, dividing the grooved damping cloth 2 into multiple uniformly sized areas. Understandably, after being divided into multiple areas, each area bears pressure independently. If the pressure in a certain area is large, only a small part of the grooved damping cloth will change shape, and the impact on the overall shape will be smaller, thereby improving the finishing time of the grooved damping cloth.

[0109] Furthermore, after the partition groove 21 is set, the polishing liquid can be stored in the partition groove 21. During the polishing process, the polishing liquid stored in the partition groove 21 can continuously wet the surface of the damping cloth under the action of vibration, thereby improving the polishing effect.

[0110] Regarding the walkie-wheel 4, during installation, it is not attached to the grooved damping cloth 2. Instead, it is suspended above the grooved damping cloth 2 via the drive shaft 42. There is a certain gap between the bottom surface of the walkie-wheel 4 and the upper surface of the grooved damping cloth 2. After the workpiece is inserted into the through hole 41, the lower surface of the workpiece is attached to the grooved damping cloth 2. This prevents the walkie-wheel 4 from applying pressure to the grooved damping cloth 2, further reducing the risk of deformation. During polishing, the drive shaft 42 drives the walkie-wheel to rotate, and the workpiece rotates along with the walkie-wheel 4. Relative rotation occurs between the workpiece and the grooved damping cloth 2, thus achieving fine polishing.

[0111] Further, step S7 includes: inspecting the surface shape, roughness, finish, dimensions, and parallelism of the final polished workpiece.

[0112] In some embodiments, when polishing with a flatbed low-profile polisher, the polishing aids include 50nm diamond powder and deionized water, with the pH adjusted to a range of 9-10, and the polishing aids are ultrasonically sonicated for 10 minutes before polishing.

[0113] Furthermore, when using a flat low-profile polishing machine for polishing, the polishing plate swing speed is 3-4 rad / min, the polishing plate swing amplitude is 11, the drive shaft 42 rotation speed is 30-35 rad / min, the temperature is controlled at 25-28℃, and the first time is 20 hours.

[0114] The processing method of this application is illustrated below through examples.

[0115] Example 1

[0116] The calcium fluoride optical component 1 (hereinafter referred to as the component) is a calcium fluoride plane mirror with dimensions of φ48×6. Product requirements: the surface shape PV of the first surface 11 and the second surface 12 is ≤1 / 8λ, the parallelism θ is ≤5″, the surface finish B is 20-10, and the surface roughness RMS is <0.4nm. The surface shape detection mentioned in this embodiment is all performed by a 633nm laser.

[0117] The specific processing flow is as follows:

[0118] (1) Chamfering and polishing

[0119] The chamfering mold is selected as: -SR33.9, a cast iron mold with a diameter of 55. The auxiliary material used for chamfering is 303# diamond abrasive. After chamfering, a polyurethane polishing mold is used to polish the chamfered edges. The polishing mold selection rule is: φ×0.707, with no cracks at the chamfer and no damage to the outer diameter.

[0120] (2) Polish the second side to a glossy finish 12

[0121] Select an aluminum disc 3 with a diameter of 280mm. Heat the aluminum disc 3 to about 70℃. Apply rosin wax evenly to the surface of the aluminum disc 3. Place the first side 11 of the part onto the aluminum disc 3 that has been coated with rosin wax. Arrange the parts in a sequence of 1, 6, 12, i.e., 1 part in the center, 6 parts in the second ring, and 12 parts in the third ring. Press the parts gently while placing them. Pay attention to whether there are any cracks in the parts after placing them on the disc. Calcium fluoride is prone to cleavage. If cleavage occurs during processing, it can easily damage the glossy surface, causing deep scratches and increasing the difficulty of later finishing. After placing the parts on the disc, perform a cooling treatment. Use an electric fan to blow on the parts at a temperature of 25-26℃ for 1.5-2 hours.

[0122] The grinding process is performed using a single-axis grinding machine with W14 abrasive (10-14μm grit). This step has two main purposes: first, to reduce the size (grinding away 0.15mm, specifically to 6.35mm) and remove the damaged layer from the blank processing; second, to control the parallelism, i.e., the edge thickness difference <0.002mm, which facilitates parallelism control during the subsequent polishing process.

[0123] Polishing is performed using a flat polishing device with 50nm diamond powder (pH range adjusted to 9-10) and deionized water as polishing aids. The bottom dimension is 0.01mm. This removes the damaged layer while ensuring that the surface shape of the rough and glossy surfaces remains unchanged when processing the other side.

[0124] The lower plate is heated, and the temperature is slowly increased to melt the rosin wax. The parts can then be removed and arranged neatly with the glossy side facing up. Next, soak them in polyacrylamide for at least half an hour to fully dissolve the rosin wax. Then, soak them in pure acetone to remove the waterproof adhesive. After rinsing off surface impurities, transfer them to a clean mixture, wipe them clean, and dry them with a clean cotton cloth. During the process, protect the parts from scratches.

[0125] (3) Polishing the first surface 11

[0126] There are two main reasons for choosing the adhesive dot plate: First, the surface shape requirements are high, and the adhesive dot plate makes it easier to produce parts with qualified surface shapes. Second, the subsequent process requires coating. After coating experiments to determine the amount of change, the surface shape of the coating substrate is required to be concave. The adhesive dots are elastic and make it easier to produce concave shapes.

[0127] For the second side (12) of the part, apply adhesive dots first. Apply waterproof adhesive evenly, then place the part in a heating oven and slowly heat to 40°C. Next, arrange adhesive dots (7mm long, 4mm in diameter) in the order of 1, 6, and 12 and adhere them to the glossy surface of the part. Let it sit for 2 hours to allow the dots and part to stabilize before mounting on the tray. Before mounting, clean the 280mm diameter glass tray with acetone to ensure it is dust-free. Arrange the surfaces to be processed (i.e., the first side (11)) neatly on the glass tray in the order of 1, 6, and 12. Place three shims symmetrically at three points along the edge of the glass tray (the shims should be 1-2mm thicker than the part). Then, heat the aluminum tray (3) and invert it onto the adhesive dots. Let it sit for about 2 hours before removing the aluminum tray (3) with the part. The mounting of the adhesive dots is now complete.

[0128] A single-axis grinding machine is used for grinding with W14 abrasive (10-14μm grit). This step has two main purposes: first, to reduce the size (grinding away 0.2mm, specifically to 6.18mm) and remove the damaged layer from the raw material processing; second, to control parallelism, i.e., edge thickness difference <0.002mm, to facilitate parallel control during subsequent polishing. Due to the low hardness, low fracture toughness, and high brittleness of calcium fluoride material, it is necessary to inspect after grinding to ensure there are no sand streaks, deep scratches, or chipped edges, ensuring that there will be no surface finish issues during polishing.

[0129] Polishing was performed using a flatbed low-profile polisher with 50nm diamond powder (pH adjusted to 9-10) as the polishing agent. The polishing plate was an asphalt rubber plate. The oscillation speed was 3 rad / min, the amplitude was 11, the spindle speed was 33 rad / min, the temperature was 26℃, and the polishing time was 20 hours. Because the diamond powder may settle after pH adjustment, it was ultrasonically dispersed for 10 minutes to ensure uniform dispersion. Before polishing, dimensions were determined. Due to the softness of calcium fluoride, a minimum dimension of 0.03mm was added during the polishing process to remove any damaging layers that might have been created during the abrasive process, ensuring a smooth finish.

[0130] The upper plate of adhesive dots corresponds to the lower plate of freezing. After applying protective adhesive, freeze in the refrigerator for at least 2 hours. Place the dots evenly on the upper plate with the polished surfaces facing up to prevent bumps and scratches. Soak the dots in clean pure acetone to remove the adhesive and gently rinse them. Then soak them in a mixed solution and wipe them clean with a clean cotton cloth to avoid creating a smooth finish during auxiliary processes.

[0131] (4) Polish the second surface 12

[0132] Because the product requires a parallelism of θ≤5″, traditional wax-sealing plates cannot guarantee parallelism. Furthermore, the parts are relatively large, and using 417 adhesive results in the adhesive's pull force concentrated on the outer diameter, leading to inconsistent surface shape during polishing. Additionally, the change in shape of individual parts after removal from the plate differs from that on the plate, increasing control difficulty. Therefore, a glossy adhesive plate is used for processing. This method ensures parallelism while also allowing for better control of the surface shape. Since the first surface 11 is concave, glossy adhesive is applied to the first surface 11, and processing the second surface 12 only requires processing it as a straight circle. After removal from the plate, the second surface 12 will spring back and naturally become a convex circle, meeting the requirements of the coating substrate.

[0133] A flat single-axis grinding machine is used for grinding, with W14 abrasive (10-14μm grit). This process also controls parallelism and lower dimensions. In addition, the part dimensions need to be determined in this process. Considering that the polishing of the second surface 12 and the rework of the first surface 11 require at least 0.05mm, the grinding process needs to grind to 6.15mm, and the edge thickness difference should be controlled within 0.002mm.

[0134] Polishing is performed using a flatbed low-profile polishing machine. The polishing additive is 50nm diamond powder (pH adjusted to 9-10, ultrasonically sonicated for 10 minutes before use). The polishing plate is an asphalt rubber plate. The oscillation speed is 3 rad / min; the oscillation amplitude is 11; the spindle speed is 33 rad / min; the temperature is 26℃; and the polishing time is 20 hours. This process also requires a 0.03mm reduction in dimension to remove any potentially damaging layers from the abrasive layer while providing the workshop with greater margin for surface shape control. Furthermore, the dimension determined in this step is 0.02mm larger than the finished product dimension, meaning the polished dimension is 6.12mm. Additionally, the parallelism in this process needs to be strictly controlled, ensuring at least θ≤3″.

[0135] Normally, the mounting plate for calcium fluoride is made by using a blade and a blowtorch to heat it. However, due to the brittle and easily cleaved nature of calcium fluoride, both of these methods would cause irreversible damage. Therefore, acetone soaking was chosen. A cotton cloth is placed at the bottom of the basin, and supports higher than the parts are symmetrically attached at three points along the edge of the plate. The plate is then inverted onto the cotton cloth at the bottom of the basin, and pure acetone is poured over it to completely submerge the plate. The parts detach by their own weight without any external force. The soaking time is uncertain and may require 24-48 hours. After soaking and rinsing, the parts are gently wiped clean with a clean mixture and a cotton cloth.

[0136] (5) Rework the first side 11

[0137] The adhesive dots were used to repair the bonding surface (i.e., the first surface 11) on the plate. Before applying the plate, the second surface 12 was evenly coated with waterproof adhesive. After the adhesive dried completely, the adhesive dots were applied. The method for applying the adhesive dots was the same as the first application, but the plate application was required to be more precise to ensure that the parallelism would not deviate during the polishing process. The size reduction was not too large, only the dots needed to be removed. The total size reduction was 0.02mm. The final size after repair was 6.1mm, which met the finished product size requirements.

[0138] For the first polishing, all parameters for the polishing equipment and auxiliary materials are the same as for the first polishing of the first surface (11). This is because if the polishing time is too long, the elastic adhesive dots can easily cause misalignment due to poor control. The dots need to be removed while maintaining parallelism.

[0139] Use a frozen lower tray. After applying protective glue, freeze in the refrigerator for at least 2 hours. Place the polished surfaces evenly on top to prevent bumps and scratches. Soak in clean pure acetone to remove the glue and gently rinse. Then soak in the mixed solution and wipe clean with a clean cotton cloth to avoid producing a smooth finish during auxiliary processes.

[0140] (6) Refined double-sided

[0141] For products that have undergone classical polishing, especially those made of brittle and soft materials like calcium fluoride, reprocessing will leave processing marks. These marks are not visible under ordinary light sources and can only be seen under Leica or high-intensity lighting. For lenses used in high-powered laser applications, these processing marks can affect their lifespan, so they need to be removed. Through experimentation, we ultimately used damping cloth for fine finishing. Compared to asphalt sheets, damping cloth is softer and can effectively remove the fine scratches left by classical polishing.

[0142] Through repeated experiments, we found that if we use conventional damping cloth for finishing, the window surface shape will change if the time is too long, affecting the quality of the finished product. Therefore, it is necessary to control the finishing time of one side to within 10 minutes. To address this, we designed a new fixture for finishing, similar to flat low polishing. We replaced the polishing disc with grooved damping cloth 2 placed below, and replaced the glossy glass disc with a whistle-equipped parabolic wheel placed above. It can be used after being installed on a low polishing machine.

[0143] This fixture has been tested and proven to have minimal impact on the surface shape of the parts. After two hours of fine finishing, the surface shape remains essentially unchanged, achieving the same finishing effect. The part is protected with adhesive on one side, placed face down in the wheel hole, and a pressure block is applied to the back. 50nm diamond powder is used as the auxiliary material. After 10 minutes of fine finishing on one side, it is cleaned, and the other side is then finished, following the same process as the first side (11). Note that the diamond powder also needs to be ultrasonically vibrated for 10 minutes before fine finishing to ensure even dispersion.

[0144] After using damping cloth for finishing, the surface roughness of the parts is significantly improved, reaching 0.3nm, which meets the surface roughness requirements of the finished product.

[0145] (7) Finished product inspection

[0146] Different testing instruments and standards are used according to requirements. The final product meets the following requirements: surface shape PV≤1 / 8λ, parallelism θ≤5″, smoothness B=20-10, and surface roughness RMS<0.4nm.

[0147] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for processing calcium fluoride optical components, characterized in that, The calcium fluoride optical component includes opposing first and second surfaces, and the processing method includes: Step S1: Chamfer and pre-polish the calcium fluoride optical component to obtain a workpiece to be pre-polished with a predetermined surface shape. Step S2: Use rosin wax to polish the first surface of the workpiece to be initially polished, and then sand and polish the second surface to obtain an initially polished workpiece with a predetermined surface shape. Step S3: Apply adhesive dots to the second surface of the initially polished workpiece, then sand and polish the first surface; Step S4: Apply the adhesive to the first surface of the initially polished workpiece, then sand and polish the second surface to obtain a second-polished workpiece with a predetermined surface shape. Step S5: Apply adhesive to the second surface of the workpiece as described in the first polishing step, and then re-polish the first surface. Step S6: Refine the surface shape of the first and second surfaces using grooved damping cloth to obtain the final polished workpiece; Step S7: Perform index testing on the final polished workpiece to meet product requirements.

2. The method for processing calcium fluoride optical components according to claim 1, characterized in that, In step S1, a cast iron mold is used in conjunction with diamond abrasive to chamfer the calcium fluoride optical parts, and a polyurethane polishing mold is used to polish the chamfered edges of the calcium fluoride optical parts to achieve preliminary polishing.

3. The method for processing calcium fluoride optical components according to claim 2, characterized in that, Step S2 includes: Heat the aluminum pan and apply rosin wax to the upper surface of the pan. Place the workpiece to be initially polished onto the upper surface of the aluminum pan. Cool the aluminum pan and apply waterproof adhesive to the first surface of the workpiece to be initially polished. The second surface is sanded using a single-axis sander; The second surface is polished using a flat low-profile polishing machine, wherein the polishing plate of the flat low-profile polishing machine is an asphalt rubber plate; Heat the aluminum disc and remove the workpiece to be initially polished. The workpiece is soaked in Polyac to remove rosin wax during the initial polishing process. The initial polished workpiece is soaked in pure acetone to remove the waterproof adhesive, thereby obtaining an initial polished workpiece with a predetermined surface shape.

4. The method for processing calcium fluoride optical components according to claim 3, characterized in that, Step S3 includes: Apply waterproof adhesive to the second surface, heat the initial polished workpiece and apply adhesive dots to the second surface, then attach the second surface to the aluminum disc through the adhesive dots. The first surface was sanded using a single-axis sander; The first surface is polished using a flat low-profile polishing machine for a first time and a first thickness. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate. Apply waterproof adhesive to the first surface, freeze the aluminum tray, remove the initially polished workpiece, soak it in pure acetone to remove the adhesive, and then soak it in a mixed solution.

5. The method for processing calcium fluoride optical components according to claim 4, characterized in that, Step S4 includes: Apply waterproof adhesive to the first surface and then attach the first surface of the initially polished workpiece to the adhesive tray. The second surface is sanded using a flat single-axis sander; The second surface is polished using a flat low-profile polishing machine for a duration of one time. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate. A support member with a thickness greater than that of the initial polished workpiece is symmetrically bonded to the edge of the adhesive tray. The adhesive tray is then inverted to suspend the initial polished workpiece in the air. The initial polished workpiece is then soaked in pure acetone until it detaches from the adhesive tray, thereby obtaining a secondary polished workpiece with a predetermined surface shape.

6. The method for processing calcium fluoride optical components according to claim 5, characterized in that, Step S5 includes: Apply waterproof adhesive to the second surface, heat the workpiece for secondary polishing, and apply adhesive dots to the second surface. Then, attach the second surface to the aluminum disc through the adhesive dots. The first surface is polished using a flat low-profile polishing machine. The polishing time is the second time, and the polishing thickness is the second thickness. The second time is less than the first time, and the second thickness is less than the first thickness. The polishing plate of the flat low-profile polishing machine is an asphalt rubber plate. The first time is 20 hours. Apply waterproof adhesive to the first surface, freeze the aluminum tray, remove the second-polished workpiece, soak it in pure acetone to remove the adhesive, and then soak it in a mixed solution.

7. The method for processing calcium fluoride optical components according to claim 6, characterized in that, In step S6, a pendulum wheel is used to perform double-sided finishing on the secondary polished workpiece. The pendulum wheel has a through hole for placing the secondary polished workpiece, and a drive shaft for rotating the pendulum wheel is connected to the pendulum wheel. The slotted damping cloth has staggered partition grooves. Step S6 includes: The grooved damping cloth is placed on the lower plate of the double-sided polishing machine, and the final polishing liquid is placed in it so that the final polishing liquid immerses the dividing groove. Apply waterproof adhesive to the second surface, place the workpiece into the through hole, place the penetrating wheel on the grooved damping cloth on the lower plate of the double-sided polishing machine, start the drive shaft, and clean the waterproof adhesive after fine polishing the first surface. Apply waterproof adhesive to the first surface, place the workpiece into the through hole, place the walkie-talkie on the polishing pad of the double-sided polishing machine, start the drive shaft, and after fine polishing the second surface, clean the waterproof adhesive.

8. The method for processing calcium fluoride optical components according to claim 1, characterized in that, Step S7 includes: The surface shape, roughness, smoothness, dimensions, and parallelism of the final polished workpiece are inspected.

9. A method for processing calcium fluoride optical components according to any one of claims 3-7, characterized in that, When using the aforementioned flat low-profile polishing machine for polishing, the polishing auxiliary materials include 50nm diamond powder and deionized water, with the pH range adjusted to 9-10. Before polishing, the polishing auxiliary materials are ultrasonically sonicated for 10 minutes.

10. A method for processing calcium fluoride optical components according to any one of claims 3-7, characterized in that, When using the aforementioned flat low-profile polishing machine for polishing, the oscillation speed of the polishing plate is 3-4 rad / min, the oscillation amplitude of the polishing plate is 11 mm, and the temperature is controlled at 25-28℃.

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