WO2021135452A1 - 一种子孔径中心供液光学表面系列加工工艺与工具 - Google Patents

一种子孔径中心供液光学表面系列加工工艺与工具 Download PDF

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Publication number
WO2021135452A1
WO2021135452A1 PCT/CN2020/117858 CN2020117858W WO2021135452A1 WO 2021135452 A1 WO2021135452 A1 WO 2021135452A1 CN 2020117858 W CN2020117858 W CN 2020117858W WO 2021135452 A1 WO2021135452 A1 WO 2021135452A1
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Prior art keywords
polishing
liquid
disc
grinding
sub
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PCT/CN2020/117858
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English (en)
French (fr)
Inventor
林彬
姜向敏
曹中臣
黄田
李世鹏
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天津大学
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Publication of WO2021135452A1 publication Critical patent/WO2021135452A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
    • B24B13/01—Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/34—Accessories
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
    • B24B57/02—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents

Definitions

  • the invention belongs to the field of optical processing, and is a series of processing techniques for ultra-smooth optical surfaces based on the principle of fluid dynamic pressure, in particular to a systematic process technology involving the processing of optical surfaces from a ground surface to an ultra-smooth surface.
  • Optical glass is widely used in aerospace, information, energy, chemical, microelectronics and other fields due to its high transparency, optical uniformity, and stable chemical properties.
  • higher requirements are put forward for the surface quality of optical components.
  • the surface quality and processing efficiency of the components are extremely demanding. Micron-level processing accuracy and nano-level surface roughness have become daily production requirements. Therefore, how to obtain higher-quality and higher-efficiency optical components during processing has become an urgent problem to be solved at present.
  • optical component processing technology needs to have the characteristics of high processing accuracy, short cycle, and low cost. Precision, efficiency, and cost have become important indicators to measure optical processing technology.
  • the usual ultra-precision processing methods are grinding, polishing and polishing. Each process has different requirements for machining accuracy and removal efficiency. In the actual machining process, it is usually necessary to use a combination of multiple polishing processes and methods.
  • the stress disk polishing with higher material removal efficiency and the traditional small grinding head polishing are usually used, and the magnetorheological polishing with stronger surface shape control ability is used in the fine polishing and surface shape dressing stage, while in the ultra-smooth surface For processing, high-energy ion beam polishing methods are usually used.
  • the existing single polishing method on the surface of the polishing process technology route cannot support the overall processing flow of the optical element, which causes the conversion between different processes in the actual manufacturing process to increase difficulty, thereby affecting the processing efficiency, and multiple installations.
  • the publication date is March 2, 2018, and the Chinese invention patent with publication number CN107745324A discloses a method for forming the surface of optical glass, which is mainly based on the polishing tool of the central liquid supply small grinding head as grinding, polishing and polishing.
  • Tools to process optical glass workpieces although this method can effectively reduce the glass surface forming time and processing accuracy, and is beneficial to improve processing efficiency.
  • it not only has higher requirements for the accuracy of the optical surface, but also proposes that the subsurface damage of the processed optical surface and the error of the optical surface in the full frequency range can be effectively controlled.
  • the low-frequency error (wavelength greater than 33mm), intermediate frequency error (wavelength between 0.25 and 33mm) and high-frequency error (wavelength less than 0.25mm) needs to be effectively controlled to meet its optical performance. Otherwise, the high-frequency and low-frequency errors will cause spherical aberration, aberration, distortion and other imaging to affect the optical imaging quality, while the high-frequency error will cause energy loss in the application of high-light optical components.
  • optical glass surface molding methods mainly target optical surface surface processing techniques and methods, but lack effective control of the full range of errors from low frequency to high frequency on the surface of large-aperture aspheric optical elements and the ability to suppress surface damage after processing.
  • the present invention proposes a series of processing techniques and tools for sub-aperture center-supply optical surfaces.
  • the method is based on the principle of center-supply fluid dynamic pressure, and the center-supply sub-aperture processing tool is applied to the secondary grinding of large-aperture optical elements
  • the processing method of cutting the surface to the super smooth surface In this method, different grinding and polishing pads and polishing pads are replaced on the same processing tool to realize the successive recursive suppression process of the low-frequency, intermediate-frequency and high-frequency errors of the optical surface.
  • the purpose of the present invention is to meet the ultra-precision, high-efficiency, and low-damage processing requirements of large-aperture aspheric optical elements and strong light optical elements, and propose the application of a sub-aperture center liquid-supply optical surface processing tool to realize the surface of the optical element from the ground surface to the ground surface. Polishing process for super smooth surface.
  • the present invention designs a sub-aperture center-liquid optical surface processing tool based on the principle of fluid dynamic pressure. The tool can quickly grind, polish, and ultra-precisely polish the ground optical surface by changing different grinding and polishing pads or polishing pads. Processing.
  • the present invention proposes a sub-aperture center liquid-supply optical surface processing tool.
  • the tool includes an elastic coupling, a polishing disk and a polishing pad.
  • One end of the polishing disk is a connecting shaft section.
  • the other end of the flexible coupling is a disc surface, one end of the flexible coupling is connected with a rotating shaft, the other end of the flexible coupling is connected to the polishing disc, and the disc surface of the polishing disc is connected to the polishing disc through an elastic adhesive layer.
  • the polishing pads are used for polishing and polishing processing
  • the type of polishing pads is one of fixed abrasive polishing pads, center-feeding small grinding head polishing skins, and disk hydrodynamic polishing pads Change different types of polishing pads according to different processing technology requirements to meet the requirements of optical element surface process design, and realize the system processing technology of optical element surface from coarse to fine; runs through the rotating shaft, the polishing disc, and the
  • the elastic bonding layer and the polishing pad are provided with a central liquid supply hole in the axial direction; when the tool is used, the tool is clamped on a motor or polishing actuator with a central liquid supply function.
  • the liquid conduit is in communication with the central liquid supply hole, and the rotating shaft is driven by a motor, so that the tool is self-propagating or planetary motion.
  • the polishing particles contained in the fixed abrasive polishing pad are one of diamond, cerium oxide and aluminum oxide polishing particles or Several kinds of mixed grinding and polishing particles, the particle size of the grinding and polishing particles ranges from 0.1 to 10 ⁇ m.
  • the polishing skin of the center-liquid-feeding small grinding head is any one of a porous polyurethane polishing sheet, a sponge polishing sheet and a polishing sheet made of synthetic fiber; the working surface of the polishing-skin of the center-liquid-supplying small grinding head has a diversion groove .
  • the material of the disc-type fluid dynamic pressure polishing pad is soft metal or polishing pitch.
  • the surface of the disc hydrodynamic polishing pad is designed with dynamic pressure grooves.
  • the disc hydrodynamic polishing pad rotates at a high speed and the polishing liquid is injected from the central liquid supply hole, the disc hydrodynamic polishing pad and A stable dynamic pressure liquid film is formed between the polished surface of the workpiece, and the polishing particles in the polishing liquid are driven by the fluid dynamic pressure in the liquid film gap to erode the surface of the workpiece, and the surface material is polished to achieve the purpose of ultra-precision polishing. .
  • the present invention also proposes a series of processing techniques for the sub-aperture center-liquid-supply optical surface using the above-mentioned sub-aperture center-liquid optical surface processing tool, which mainly includes fluid dynamic pressure consolidated abrasive grinding and polishing, center-liquid-supply small grinding head polishing and Disc hydrodynamic polishing.
  • Step 1 Fluid dynamic pressure fixed abrasive grinding and polishing: clamp the processing tool bonded with the fixed abrasive grinding and polishing pad to the motor or polishing actuator with the function of central liquid supply, and adjust the surface of the grinding and polishing pad to be processed
  • the surface of the workpiece is in contact;
  • the grinding fluid is injected into the center liquid supply hole of the tool, the grinding and polishing plate is driven by the rotating shaft to rotate, the speed range is 50-1000rpm;
  • the load is applied on the rotating shaft while rotating, the load range is 10-50N;
  • the processing tool is controlled The path moves according to the grid trajectory, and the moving speed range is 0.5-5mm/s;
  • the feed path of the processing tool is changed to perform multiple rounds of processing on the surface of the workpiece, and after 1 to 3 rounds of processing, the low-frequency and intermediate-frequency errors of the optical surface are suppressed;
  • Step 2 Polishing of the center liquid supply small grinding head: clean the surface after polishing; replace the grinding and polishing pad on the processing tool with the center liquid supply small grinding head polishing skin, use cerium oxide or cerium oxide with a concentration of 5% to 15% Alumina polishing liquid, the polishing liquid is injected into the central liquid supply hole at a certain pressure, and the supply pressure of the polishing liquid is: 0.1 ⁇ 0.5Mpa; the axial load of 10 ⁇ 30N is applied to the polishing disc through the rotating shaft, and the polishing disc is 200 ⁇ 200 ⁇ 1000r/min rotation speed, 50 ⁇ 200rpm speed revolution, the eccentricity of the polishing disc revolution/rotation is 0.1 ⁇ 1.0; during the polishing process, the polishing path of the polishing disc is controlled to move according to the grid or random trajectory, and the moving speed range is: 0.1 ⁇ 10mm/s, so that the polishing disc can process the entire processing surface and complete the first small grinding head polishing process; then according to the above parameters, repeat the polishing for many times to suppress the intermediate and high frequency
  • Step 3 Disc hydrodynamic polishing: clean the polished surface; replace the polishing pad on the processing tool with a disc hydrodynamic polishing pad, and polish 10-20% cerium oxide or alumina
  • the polishing liquid is injected into the central liquid supply hole at a certain pressure.
  • the supply pressure of the polishing liquid is 0.5 ⁇ 2Mpa; the axial load of 20 ⁇ 50N is applied to the polishing disk through the rotating shaft, and the polishing disk is at a speed of 1000-8000r/min. Rotate, control the polishing path of the polishing disk to move according to the grid or random trajectory.
  • the moving speed of the polishing tool ranges from 1 to 10 mm/s, so that the polishing disk can homogenize the entire processing surface and complete the first small grinding head polishing process; Then according to the above parameters, the polishing is repeated many times to suppress the high frequency error of the optical surface; so far, the processing of the super smooth surface is realized.
  • the sub-aperture center liquid-supplying optical surface series processing method of the present invention is an optical surface processing technology based on the principle of fluid dynamic pressure.
  • the series of processing technologies include fluid dynamic pressure consolidated abrasive grinding and polishing technology, and center liquid-supplying small grinding technology. Head polishing technology and disc fluid dynamic pressure polishing technology.
  • the grinding and polishing/polishing process of the system can effectively suppress the low-frequency, intermediate-frequency and high-frequency errors of the optical surface, and obtain an ultra-smooth optical surface with a surface error of less than 1nm, and it is in the process of processing It can effectively control its surface and sub-surface damage in different process stages.
  • the depth of the sub-surface damage layer can be effectively controlled within 1 ⁇ m.
  • the processing tool of the present invention can effectively improve the service life of the grinding and polishing pad, and improve the stability of the material removal efficiency of the grinding and polishing/polishing process.
  • the processing tools and processing methods of the present invention are suitable for all kinds of optical materials of metal and non-metal materials, and can be used with multi-degree-of-freedom polishing machine tools and motion platforms to realize the processing indicated by planes, large curvature aspheric surfaces and free-form surfaces .
  • Fig. 1 is a schematic diagram of the three-dimensional structure of a sub-aperture center-supply optical surface processing tool of the present invention
  • FIG. 2 is a schematic diagram of the structure of Embodiment 1 of the polishing pad shown in FIG. 1;
  • FIG. 3 is a schematic diagram of the structure of Embodiment 2 of the polishing pad shown in FIG. 1;
  • Embodiment 3 is a schematic structural diagram of Embodiment 3 of the polishing pad shown in FIG. 1;
  • FIG. 1 Schematic diagram of grid track grinding/polishing
  • Figure 6 Schematic diagram of planetary trajectory grinding/polishing
  • Fig. 7 Schematic diagram of the full frequency error control of the optical processing process surface
  • FIG. 8 Schematic diagram of sub-surface damage suppression in optical processing technology.
  • a sub-aperture center liquid-supply optical surface processing tool includes an elastic coupling 1, a polishing disc 3, and a polishing pad 5.
  • One end of the polishing disc 3 is a connecting shaft section.
  • the other end of the polishing disc 3 is a disc surface, the size of the polishing disc 3 is between 1/5 and 1/10 of the size of the processed optical element, and the diameter of the polishing disc 3 can range from 10 to 100 mm;
  • the flexible coupling One end of 1 is connected with a rotating shaft 6, the other end of the flexible coupling 1 is connected with the polishing disk 3, and the disk surface of the polishing disk 3 is bonded to the polishing pad 5 through an elastic bonding layer 4,
  • the polishing pad 5 is used for grinding, polishing and polishing, and the type of the polishing pad 5 is one of a fixed abrasive polishing pad 501, a center-liquid small grinding head polishing skin 502, and a disc hydrodynamic pressure polishing pad 503 ; Different types of grinding and polishing pads or polish
  • the grinding and polishing particles contained in the fixed abrasive polishing pad 501 are one or a mixture of diamond, cerium oxide and aluminum oxide grinding and polishing particles, and the particle size of the grinding and polishing particles ranges from 0.1 to 10 ⁇ m, it can process different materials of optical glass such as silicon carbide, quartz glass, K9, BK7, etc.; it is used as a grinding fluid when processing with a fixed abrasive polishing pad; a fixed abrasive polishing pad is used to quickly remove the surface residue after grinding The low-frequency error and the sub-surface damage;
  • Figure 2 shows a schematic diagram of the fixed abrasive polishing pad 501.
  • the center liquid supply small grinding head polishing skin 502 is any one of a porous polyurethane polishing sheet, a sponge polishing sheet and a polishing sheet made of synthetic fibers; the working surface of the center liquid supply small grinding head polishing skin 502 has a guide Flow groove, the polishing liquid used in the processing of polishing skin is a polishing liquid composed of one or more of diamond, cerium oxide, and alumina fine particles; the application of polishing skin can quickly remove the residual intermediate frequency on the surface after grinding and polishing of the fixed abrasive. And part of the high-frequency error and the sub-surface damage layer;
  • Figure 2 shows a schematic diagram of the polishing skin 502 of the small grinding head with the center liquid supply.
  • the material of the disc fluid dynamic pressure polishing pad 503 is soft metal or polishing pitch.
  • the surface of the disc hydrodynamic polishing pad 503 is designed with dynamic pressure grooves.
  • Figure 4 shows a schematic diagram of the disc hydrodynamic polishing pad 503.
  • the sub-aperture center-liquid optical surface processing tool provided by the present invention adopts a center-liquid mode, and the polishing liquid or polishing liquid is supplied from the center hole of the tool and flows out from the center area of the polishing pad/polishing pad;
  • a central liquid supply hole 500 is provided in the axial direction of the rotating shaft 6, the polishing disc 3, the elastic bonding layer 4 and the polishing pad 5; when the tool is used, the tool is clamped in On a motor or polishing actuator with a central liquid supply function, the liquid supply conduit of the motor or the polishing actuator is in communication with the central liquid supply hole 500, and the rotating shaft 6 is driven by the motor, so that the tool is self-transporting or Planetary movement.
  • the polishing pad is in direct contact with the polishing surface.
  • the processing tool and the polishing surface are formed by controlling the polishing fluid/polishing fluid supply pressure, the tool speed, and the load imposed on the tool.
  • the flexible coupling is axially compressed under the action of fluid dynamic pressure to "float" the processing tool and separate the processing tool from the surface of the polished workpiece to form a liquid film gap (range of liquid film gap: 0.05 ⁇ 1mm) , So as to reduce the direct contact between the polishing pad or polishing pad and the polishing surface.
  • the depth of cut of the grinding and polishing particles can be changed, and the erosion effect of the free abrasive in the liquid film gap on the machined surface is further affected.
  • the removal rate of surface material is effectively controlled; in addition, it can also avoid the influence of polishing particles on the surface quality after polishing while the unstable scratching of the polishing particles removes the material.
  • the present invention proposes a super-smooth optical surface polishing systematic process method, including sequential fluid dynamic pressure consolidated abrasive grinding and polishing, and center liquid-supplying small Grinding head polishing and disc fluid dynamic pressure polishing.
  • the processing tool of the present invention (with different polishing layers) is installed on a motor or other polishing actuator with a central liquid supply function, and the motor is used to drive the polishing disk to rotate.
  • the rotating speed of the polishing disk ranges from 50 to 8000 rpm;
  • the liquid or polishing liquid is injected from the central soft tube 2 of its central liquid supply hole, and flows out from the center hole of the polishing pad/polishing pad.
  • the supply pressure of the polishing liquid/polishing liquid ranges from 0.1 to 2 MPa; while the polishing disc is rotating, Axial load is applied by an external cylinder or other pressure module, and the load range acting on the surface of the polishing disc: 0.1-100N.
  • the processing tool shown in Fig. 1 and the polishing pad or polishing pad shown in Fig. 2, Fig. 3, and Fig. 4 are used in a series of processing techniques for a sub-aperture center liquid-supply optical surface proposed by the present invention.
  • the method is a A systematic polishing method from the ground optical surface to the super smooth surface.
  • the tool of the present invention is clamped on a motor with a central liquid supply function or other polishing actuators, so that the liquid supply pipe and the center liquid supply hole of the sub-aperture center liquid supply optical surface processing tool are connected; the processing tool is driven to rotate or rotate by the motor Planetary motion
  • applying the processing method of the present invention includes the following steps:
  • Step 1 Fluid dynamic pressure consolidated abrasive grinding and polishing process: the consolidated abrasive polishing pad 501 is bonded to the surface of the polishing disk 3 through the elastic bonding layer 4, and the polishing pad is moved to connect the surface of the polishing pad to the surface to be polished.
  • the surface of the processed workpiece is in contact; the grinding fluid is injected into the liquid supply hole of the center of the processing tool.
  • the supply pressure of the grinding fluid is 0.1 ⁇ 2MPa.
  • the rotating shaft drives the polishing disc to rotate at a speed of 800rpm; while rotating, a load is applied on the rotating shaft,
  • the load is 30N;
  • the path of the processing tool is controlled to move according to a grid or random trajectory
  • Figure 5 is a schematic diagram of grid trajectory grinding/polishing
  • Figure 6 is a schematic diagram of planetary trajectory grinding/polishing
  • 7 is the surface of the polishing workpiece
  • 701 is Grid grinding/polishing trajectory
  • 702 is planetary polishing trajectory
  • the moving speed range is 1.5mm/s
  • the sub-surface damage layer can be reduced
  • the bumps of the grinding and polishing pad that is, the grinding and polishing particles of the fixed abrasive grinding and polishing pad 501
  • the surface of the workpiece produce a fluid dynamic pressure effect.
  • the gap controls the depth of penetration between the abrasive particles and the surface of the workpiece and the amount of material removed to realize the deterministic processing technology of the optical element surface.
  • Step 2 Polishing process of the center-liquid-supply small grinding head: clean the surface after polishing, remove the consolidated abrasive polishing pad 501 from the polishing disc 3, and pass the polishing skin 502 of the center-liquid-supply small grinding head through the elastic bonding layer 4 Adhere to the surface of the polishing disc 3, use a 10% concentration of cerium oxide or alumina polishing solution, inject the polishing solution into the central liquid supply hole at a pressure of 1Mpa; apply a 20N axial load to the polishing disc through the rotating shaft 6,
  • the polishing disc rotates at a speed of 1500r/min, revolves at a speed of 250rpm, and the eccentricity of the revolution/rotation of the polishing disc is 0.5; during the polishing process, the polishing path of the polishing disc is controlled to move according to a grid track or a random track.
  • the moving speed range is: 4.5mm/s, so that the polishing head can process the entire optical glass surface; before this step of polishing, the optical surface profile after step 1 grinding and polishing is detected, the residual error and the amount of material removal are calculated, and the matrix equation-based
  • the residence time model calculates the residence time corresponding to the surface shape convergence, and completes the first polishing process of the small grinding head. Then repeat the above parameters and perform multiple polishing to suppress the medium and high frequency errors of the optical surface.
  • the sub-surface damage layer formed on the surface after polishing, the depth of the residual sub-surface damage layer after polishing is less than 3 ⁇ m.
  • the polishing liquid is evenly distributed on the surface of the polishing disk from the center hole.
  • a uniform liquid film gap is formed between the polishing pad and the polishing surface.
  • the polishing pad and the workpiece The surface is between semi-contact and non-contact; the polishing particles in the liquid film gap are driven by the polishing tool to scratch the optical surface to achieve the purpose of polishing; during the polishing process, the supply pressure of the polishing liquid, the rotation speed of the polishing tool and the polishing are controlled.
  • the axial load on the tool is used to control the formation of the liquid film gap and the removal rate of material.
  • Step 3 Disc type hydrodynamic pressure polishing: clean the above-mentioned polished optical glass; remove the polishing skin 502 from the polishing disc 3 for the center liquid-supplying small grinding head, and apply the disc hydrodynamic pressure polishing pad 503 through elastic viscose
  • the bonding layer 4 is adhered to the surface of the polishing disc 3, using 10% cerium oxide as the polishing liquid, and the polishing liquid is injected into the central liquid supply hole at a pressure of 1.5Mpa; the polishing disc 3 is applied to the polishing disc 3 through the rotating shaft 6 Load to 50N while the polishing disk rotates at a speed of 3000r/min.
  • the polishing path of the polishing disk is controlled to move according to a grid or random trajectory.
  • the moving speed of the polishing tool is 2mm/s, so that the polishing head can homogenize and process the entire optical glass surface. Repeated polishing several times to suppress the high frequency error of the optical surface, the residual surface error after polishing is less than 1nm; the depth of the sub-surface damage layer is less than 1 ⁇ m.
  • the polishing liquid is evenly distributed on the surface of the polishing disc from the center hole along the dynamic pressure groove of the polishing disc surface.
  • a uniform surface is formed between the polishing pad and the polishing surface. Liquid film gap.
  • the polishing pad is in a non-contact state with the surface of the workpiece, and the polishing particles in the polishing liquid are driven by the fluid dynamic pressure in the liquid film gap to erode the surface of the workpiece and polish the surface material; dynamic pressure grooves on the surface of the polishing disc It can effectively summarize the fluid dynamic pressure in the liquid film gap, thereby improving the polishing efficiency; in the polishing process, by controlling the polishing fluid supply pressure, the rotating speed of the polishing tool, and the axial load on the polishing tool, it is used to control the fluid dynamics in the liquid film gap. Pressure to realize the processing technology of ultra-smooth surface.
  • the optical surface after grinding is applied with a fluid dynamic pressure consolidated abrasive grinding and polishing process to reduce the low frequency and part of the intermediate frequency error of the optical surface, while reducing the depth of the subsurface damage layer to less than 5 ⁇ m; then apply the center liquid supply
  • the polishing process of the lower grinding head reduces the intermediate frequency and some high frequency errors of the optical surface, and the depth of the sub-surface damage layer is reduced to below 3 ⁇ m; finally, the disk hydrodynamic polishing process is used to reduce the high frequency error of the optical surface, and the depth of the subsurface damage layer is reduced to below 1 ⁇ m.
  • FIG. 7 is a schematic diagram of the optical processing process surface full-frequency error control of the present invention
  • FIG. 8 is the optical surface of the present invention. Schematic diagram of sub-surface damage suppression in the processing process.
  • the surface of the optical element after grinding is respectively subjected to the fluid dynamic pressure consolidated abrasive grinding and polishing process, the center liquid-feeding small grinding head polishing process, and the disc fluid dynamic pressure polishing process to reduce the optical element subsurface layer by layer. Depth of surface damage layer.

Abstract

一种子孔径中心供液光学表面加工工具，包含有弹性联轴器（1）、抛光盘（3）、抛光垫（5），弹性联轴器（1）两端分别连接抛光盘（3）和旋转轴（6），在同一加工工具上通过更换不同的磨抛垫和抛光垫，以实现光学表面低频、中频及高频误差的逐次递归的抑制过程。同时，为获得高质量、低损伤的超精密光滑表面，不同磨抛抛光垫的组合应用，将前序工艺抛光表面后残余的亚表面损伤层去除同时不再形成新的亚表面损伤，经过多次加工使亚表面损伤降低至最小。还涉及一种子孔径中心供液光学表面系列加工工艺，该系列加工工艺是基于流体动压原理从毛坯表面到超光滑表面的系统性工艺方法，主要包括流体动压固结磨料磨抛工序、中心供液小磨头抛光工序以及盘式流体动压抛光工序。

Description

一种子孔径中心供液光学表面系列加工工艺与工具 技术领域
本发明属于光学加工领域，是一种基于流体动压原理的超光滑光学表面系列加工工艺，特别是一种涉及光学表面从磨削后表面到超光滑表面加工的系统工艺技术。
背景技术
光学玻璃由于其具有透明性高、光学均匀性、化学性能稳定等特性，被广泛应用于航天,信息,能源,化工,微电子等领域。随着光学技术的蓬勃发展和光学材料应用的日益广泛，对光学元件的表面质量提出了更高的要求。特别针对于高功率激光装置系统，微型机电系统等大型的光学系统，对元件的表面质量和加工效率要求极为苛刻，微米级的加工精度以及纳米级的表面粗糙度已经成为了日常的生产需求。因此，如何在加工过程中获得更高质量，更高效率的光学元件成为了目前急于待解决的问题。
为了满足现代先进光学技术的应用需求，光学元件加工技术需要具备加工精度高、周期短、成本低等特征，精度、效率、成本已经成为衡量光学加工技术的重要指标。为了获得高质量的光学玻璃、硅片、砷化镓等硬脆性材料通常进行的超精密加工方法是磨抛和抛光。每一道工序对加工精度和去除效率的要求都有所不同。在实际加工过程中，通常需要结合使用多种抛光工艺和方法。例如，通常在磨抛阶段使用材料去除效率较高的应力盘抛光和传统小磨头抛光，在精抛和面形修整阶段使用面形控制能力更强的磁流变抛光，而在超光滑表面加工方面通常使用高能离子束抛光方法。现有的抛光工艺技术路线表面单一的抛光方法无法支撑光学元件的整体加工流程，这就造成了在实际制造过程中不同工艺之间的转换增加了困难，从而影响加工效率，并且多次装卡工件或工具造成的定位基准改变等，造成加工精度和加工效率的下降。
基于以上问题，公开日为2018年3月2日，公开号为CN 107745324 A的中国发明专利披露了一种光学玻璃表面成型方法，主要是基于中心供液小磨头抛光工具作为磨抛和抛光工具来加工光学玻璃工件；虽然该方法能够有效降低玻璃表面成型时间和加工精度，而且有利于提高加工效率。然而，随着现代光学技术的发展，一方面不仅对光学表面精度具有较高的要求，而且同时也提出对加工后光学表面的亚表面损伤和光学表面在全频段内误差都能得到有效控制。根据大口径光学元件加工技术要求和国际标准(ISO10110)对大口 径非球面光学元件在其低频误差(波长大于33mm)、中频误差(波长介于0.25至33mm之间)以及高频误差(波长小于0.25mm)均需要得到有效控制才能满足其光学使用性能。否则，其高频和低频误差会引起球差、像差、畸变等成像影响光学的成像质量，而高频误差在强光光学元件应用中会引起能量的损失。上述光学玻璃表面成型方法中主要针对的光学表面面型加工工艺和方法，而缺乏对大口径非球面光学元件表面从低频到高频的全频段内误差的有效控制和加工后表面损伤抑制能力。
发明内容
针对上述现有技术，本发明提出一种子孔径中心供液光学表面系列加工工艺与工具，该方法基于中心供液流体动压原理，将中心供液子孔径加工工具应用于大口径光学元件从磨削后表面到超光滑表面的加工方法。该方法在同一加工工具上通过更换不同的磨抛垫和抛光垫，以实现光学表面低频、中频及高频误差的逐次递归的抑制过程。同时，为获得高质量、低损伤的超精密光滑表面，不同磨抛抛光垫的组合应用，将前序工艺抛光表面后表明残余的亚表面损伤层去除同时不再形成新的亚表面损伤，经过多次加工使亚表面损伤降低至最小。
本发明的目的是针对大口径非球面光学元件以及强光光学元件的超精密、高效、低损伤的加工需求，提出应用子孔径中心供液光学表面加工工具实现光学元件表面从磨削后表面到超光滑表面的抛光工艺。本发明基于流体动压原理设计出一种子孔径中心供液光学表面加工工具，该工具通过更换不同的磨抛垫或抛光垫能够对磨削后的光学表面进行快速磨抛、抛光以及超精密抛光加工。
为了解决上述技术问题，本发明提出的一种子孔径中心供液光学表面加工工具，该工具包含有弹性联轴器、抛光盘和抛光垫，所述抛光盘一端为连接轴段，所述抛光盘的另一端为盘面，所述柔性联轴器的一端连接有旋转轴，所述柔性联轴器的另一端与所述抛光盘连接，所述抛光盘的盘面上通过弹性粘接层与所述抛光垫粘接，所述抛光垫用于磨抛和抛光加工，所述抛光垫的类型是固结磨料抛光垫、中心供液小磨头抛光皮以及盘式流体动压抛光垫中的一种；根据不同的加工工艺要求更换不同类型的抛光垫，以达到光学元件表面工艺设计的需求，实现光学元件表面从粗到精的系统加工工艺；贯穿于所述旋转轴、所述抛光盘、所述弹性粘接层和抛光垫的轴向设有中心供液孔；使用该工具时，该工具装夹于具有中心供液功能的电机或者抛光执行器上，所述电机或者抛光执行器的供液导管与所述 中心供液孔导通，通过电机驱动所述旋转轴，从而使该工具自传或行星运动。
进一步讲，本发明所述的子孔径中心供液光学表面加工工具，其中，所述固结磨料磨抛垫中含有的磨抛颗粒是金刚石、氧化铈和氧化铝磨抛颗粒的其中一种或几种混合磨抛颗粒，所述磨抛颗粒的粒径范围为0.1～10μm。
所述中心供液小磨头抛光皮是多孔聚氨酯抛光片、海绵抛光片和合成纤维制成的抛光片中的任何一种；所述中心供液小磨头抛光皮的工作表面具有导流槽。
所述盘式流体动压抛光垫的材质是软质金属或是抛光沥青。
所述盘式流体动压抛光垫的表面设计有动压槽，当所述盘式流体动压抛光垫高速旋转、抛光液从中心供液孔注入时，所述盘式流体动压抛光垫与工件的抛光加工表面之间形成稳定的动压液膜，依靠液膜间隙内的流体动压力驱动所述抛光液中的抛光颗粒冲蚀工件表面、抛光加工表面材料以达到超精密抛光工艺的目的。
同时，本发明中还提出了利用上述子孔径中心供液光学表面加工工具的子孔径中心供液光学表面系列加工工艺，主要包括流体动压固结磨料磨抛、中心供液小磨头抛光以及盘式流体动压抛光。
进一步讲，所述的子孔径中心供液光学表面系列加工工艺的具体步骤如下：
步骤1、流体动压固结磨料磨抛：将粘接有固结磨料磨抛垫的加工工具装夹于具有中心供液功能的电机或者抛光执行器上，调整磨抛垫的表面与待加工工件表面接触；将研磨液注入工具的中心供液孔内，由旋转轴驱动磨抛盘转动，转速范围50-1000rpm；在转动的同时在旋转轴上施加载荷，载荷范围10～50N；控制加工工具的路径，按照栅格轨迹移动，移动速度范围为0.5～5mm/s；改变加工工具的进给路径对工件表面进行多轮加工，经过1～3轮加工，抑制光学表面的低频和中频误差；
步骤2、中心供液小磨头抛光：将磨抛后表面进行清洗；将加工工具上的磨抛垫更换为中心供液小磨头抛光皮，使用浓度为5％～15％的氧化铈或氧化铝抛光液，将抛光液以一定压力注入中心供液孔，抛光液供给压力范围为：0.1～0.5Mpa；通过旋转轴对抛光盘施加10～30N的轴向载荷，并且抛光盘以200～1000r/min速度自转，50～200rpm的速度公转，抛光盘公转/自转的偏心率为0.1～1.0；在抛光过程中，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，移动速度范围为：0.1～10mm/s，使得抛光盘能够加工整个加工表面，完成第一次小磨头抛光工艺；然后按照上述参数，重复进行多次抛光，抑制光学表面的中频和高频误差；
步骤3、盘式流体动压抛光：将抛光后表面进行清洗；将加工工具上的磨抛垫更换为盘式流体动压抛光垫，将浓度为10％～20％的氧化铈或氧化铝抛光液，将抛光液以一定压力注入中心供液孔，抛光液供给压力范围为：0.5～2Mpa；通过旋转轴对抛光盘施加20～50N的轴向载荷，同时抛光盘以1000-8000r/min速度自转，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，抛光工具移动速度范围为：1～10mm/s，使得抛光盘能够匀化加工整个加工表面，完成第一次小磨头抛光工艺；然后按照上述参数，重复进行多次抛光，抑制光学表面的高频误差；至此实现超光滑表面的加工。
与现有技术相比，本发明的有益效果是：
(1)本发明所述的子孔径中心供液光学表面系列加工方法是基于流体动压原理的光学表面加工工艺，该系列加工工艺包括流体动压固结磨料磨抛技术、中心供液小磨头抛光技术及盘式流体动压抛光技术，应用该系统的磨抛/抛光工艺可以有效抑制光学表面低频、中频及高频误差，并获得表面误差小于1nm的超光滑光学表面，且加工过程中在不同的工艺阶段可有效控制其表面及亚表面损伤。经过该系列加工工艺，亚表面损伤层深度可有效控制在1μm以内。
(2)提供的基于流体动压原理的光学玻璃超光滑表面抛光装置和工艺经过中心供液流体动压固结磨料磨抛技术、中心供液小磨头抛光技术和盘式流体动压抛光技术，整个抛光过程中只需要更换对应的抛光垫、抛光液以及设置相应的工艺参数，不需更换机床及夹具等，减少了频繁更换工具的装夹时间，同时降低了装卡及更换机床带来的误差，该工艺方法在保证精度的前提下，极大的提高加工精度和抛光效率，其加工效率相比于传统的多种抛光机床及抛光工艺组合的方法，本发明提出的子孔径流体动压抛光方法的加工效率能够提高3倍以上。
(3)本发明所述的流体动压固结磨料磨抛技术，由于抛光垫表面存在粗糙峰和动压槽的设计，形成的稳定液膜产生不可忽视的流体动压作用，使磨抛工具“上浮”，并将原本完全接触的磨抛垫和工件分离开来，产生不完全接触的效果。该技术既保证了磨抛粒与工件表面的柔性接触，又实现了在延性去除的效果下，尽可能减小亚表面损伤。
(4)本发明所述的中心供液小磨头抛光技术，由于传统小磨头抛光从四周供给抛光液，因而存在抛光液不易进入工具中心区域，中心区域抛光液磨粒更新速度慢等缺陷。本发明所述加工工具，可以有效改进磨抛垫的寿命，改善磨抛/抛光工艺材料去除效率的稳定性。
(5)本发明所述的加工工具和加工方法适用于各类金属、非金属材质的光学材料，并且配合多自由度抛光机床和运动平台可实现平面、大曲率非球面和自由曲面表明的加工。
附图说明
图1为本发明子孔径中心供液光学表面加工工具立体结构示意图；
图2为图1中所示抛光垫实施例1的结构示意图；
图3为图1中所示抛光垫实施例2的结构示意图；
图4为图1中所示抛光垫实施例3的结构示意图；
图5栅格轨迹研磨/抛光示意图；
图6行星轨迹研磨/抛光示意图；
图7光学加工工艺表面全频段误差控制示意图；
图8光学加工工艺亚表面损伤抑制示意图。
图中：1-弹性联轴器，2-中心软导管，3-抛光盘，4-弹性粘接层，5-抛光垫，6-旋转轴，500-中心供液孔，501-固结磨料磨抛垫，502-中心供液小磨头抛光皮，503-盘式流体动压抛光垫，7-抛光工件表面，701-栅格研磨/抛光轨迹，702-行星抛光轨迹。
具体实施方式
下面结合附图及具体实施例对本发明做进一步的说明，但下述实施例绝非对本发明有任何限制。
如图1所示，本发明提出的一种子孔径中心供液光学表面加工工具，包含有弹性联轴器1、抛光盘3和抛光垫5，所述抛光盘3一端为连接轴段，所述抛光盘3的另一端为盘面，抛光盘3的尺寸为所加工光学元件尺寸的1/5～1/10之间，抛光盘3的直径范围可为：10～100mm；所述柔性联轴器1的一端连接有旋转轴6，所述柔性联轴器1的另一端与所述抛光盘3连接，所述抛光盘3的盘面上通过弹性粘接层4与所述抛光垫5粘接，所述抛光垫5用于磨抛和抛光加工，所述抛光垫5的类型是固结磨料抛光垫501、中心供液小磨头抛光皮502以及盘式流体动压抛光垫503中的一种；可根据不同的加工工艺要求更换不同类型的磨抛垫或抛光垫，以达到光学元件表面工艺设计的需求；通常先经有固结磨料磨抛垫加工，然后更换为中心供液小磨头抛光皮，最后应用盘式流体动压抛光垫，实现光学元件表面从“粗”到“精”的系统加工工艺。
所述固结磨料磨抛垫501中含有的磨抛颗粒是金刚石、氧化铈和氧化铝磨抛颗粒的其中一种或几种混合磨抛颗粒，所述磨抛颗粒的粒径范围为0.1～10μm，可分别加工碳化硅、石英玻璃、K9、BK7等不同材质的光学玻璃；用固结磨料磨抛垫加工时所用为研磨液；应用固结磨料磨抛垫以快速去除磨削后表面残余的低频误差和亚表面损伤；图2示出的是该固结磨料磨抛垫501的示意图。
所述中心供液小磨头抛光皮502是多孔聚氨酯抛光片、海绵抛光片和合成纤维制成的抛光片中的任何一种；所述中心供液小磨头抛光皮502的工作表面具有导流槽，应用抛光皮加工时所用抛光液为金刚石、氧化铈、氧化铝微细颗粒其中的一种或几种混合物配置的抛光液；应用抛光皮可以快速去除固结磨料磨抛后表面残留的中频和部分高频误差以及亚表面损伤层；图2示出的是该中心供液小磨头抛光皮502的示意图。
所述盘式流体动压抛光垫503的材质是软质金属或是抛光沥青。所述盘式流体动压抛光垫503的表面设计有动压槽，图4示出的是该盘式流体动压抛光垫503的示意图，当所述盘式流体动压抛光垫503高速旋转、抛光液从中心供液孔500注入时，所述盘式流体动压抛光垫503与工件的抛光加工表面之间形成稳定的动压液膜，依靠液膜间隙内的流体动压力驱动所述盘式流体动压抛光垫503材质中的抛光颗粒冲蚀工件的抛光加工表面材料以达到超精密抛光工艺的目的。
本发明所提的子孔径中心供液光学表面加工工具采用中心供液的方式，磨抛液或抛光液从工具的中心孔供给，并从磨抛垫/抛光垫的中心区域流出；本发明的加工工具中，贯穿于所述旋转轴6、所述抛光盘3、所述弹性粘接层4和抛光垫5的轴向设有中心供液孔500；使用该工具时，该工具装夹于具有中心供液功能的电机或者抛光执行器上，所述电机或者抛光执行器的供液导管与所述中心供液孔500导通，通过电机驱动所述旋转轴6，从而使该工具自传或行星运动。不同于传统的小工具抛光技术中抛光垫与抛光表面直接接触，流体动压抛光技术中，通过控制磨抛液/抛光液供给压力、工具转速以及工具上施加的载荷使得加工工具与抛光表面形成稳定的流体动压力，柔性联轴器在流体动压力作用下轴向压缩，使加工工具“上浮”，将加工工具与抛光工件表面分离，形成液膜间隙(液膜间隙范围：0.05～1mm)，从而减小磨抛垫或抛光垫直接与抛光表面接触，由于液膜间隙的存在可以改变研磨和抛光颗粒的切深，以及液膜间隙内游离磨料对加工表面的冲蚀效果，进而对加工表面材料去除率得到有效控制；此外还可以避免抛光颗粒不稳定划擦去除材料的同时对抛光后表面质量的影响。
本发明基于上述抛光原理和所述子孔径中心供液光学表面加工工具，提出了一种超光滑光学表面抛光系统性工艺方法，包括顺序进行的流体动压固结磨料磨抛、中心供液小磨头抛光以及盘式流体动压抛光。
将本发明(带有不同抛光层)的加工工具安装于具有中心供液功能的电机或其它抛光执行器上，利用电机驱动抛光盘旋转，抛光盘的转速范围为:50～8000rpm；同时将研磨液或抛光液从其中心供液孔的中心软导管2内注入，从磨抛垫/抛光垫中心孔流出，研磨液/抛光液的供给压力范围为0.1～2MPa；抛光盘在旋转的同时，由外部气缸或者其它压力模块施加轴向载荷，作用在抛光盘表面上载荷范围：0.1～100N。
本发明所提出的一种子孔径中心供液光学表面系列加工工艺中应用如图1所示的加工工具和如图2、图3、图4所示的磨抛垫或抛光垫，该方法是一种由磨削后的光学表面到超光滑表面的系统性抛光方法。将本发明工具装夹于具有中心供液功能的电机或者其他抛光执行器上，使供液导管与子孔径中心供液光学表面加工工具的中心供液孔导通；通过电机驱动加工工具自转或行星运动；
在本实例中，应用本发明所述的加工方法包含以下步骤：
步骤1、流体动压固结磨料磨抛工序：将固结磨料磨抛垫501通过弹性粘接层4粘接到抛光盘3表面，移动所述抛光垫，将所述抛光垫的表面与待加工工件表面接触；将研磨液注入加工工具中心供液孔内，研磨液的供给压力为0.1～2MPa，由旋转轴驱动抛光盘转动，转速为800rpm；在转动的同时在旋转轴上施加载荷，载荷为30N；控制加工工具的路径，按照栅格或随机轨迹移动(图5是栅格轨迹研磨/抛光示意图，图6是行星轨迹研磨/抛光示意图，图中，7为抛光工件表面，701为栅格研磨/抛光轨迹，702为行星抛光轨迹)，移动速度范围为1.5mm/s，改变磨抛工具的进给方向和路径对样件表面进行多轮加工，经过3轮加工，抑制光学表面低频和中频误差，应用白光干涉仪或接触式表面轮廓仪测量其表面面型轮廓误差小于1.58λ(λ＝632.8nm)；由固结磨料磨抛垫加工后可有效去除光学玻璃毛坯件表面的亚表面损伤层，应用截面刻蚀或差动刻蚀法克测量加工后亚表面损伤层可减小到5μm内。
在固结磨料磨抛过程中，磨抛垫凸起块(即固结磨料磨抛垫501的磨抛颗粒)与工件表面产生流体动压效应，通过控制磨抛工艺参数，产生的稳定液膜间隙，进而控制磨粒与工件表面的切入深以及材料去除量，实现光学元件表面确定性加工工艺。
步骤2、中心供液小磨头抛光工序：将磨抛后表面进行清洗，从抛光盘3上揭下固结磨料磨抛垫501，将中心供液小磨头抛光皮502通过弹性粘接层4粘接到抛光盘3表面，使用浓度为10％的氧化铈或氧化铝抛光液，将抛光液以1Mpa的压力注入中心供液孔；通过旋转轴6对抛光盘施加20N的轴向载荷，并且抛光盘以1500r/min速度自转，250rpm的速度公转，抛光盘公转/自转的偏心率为0.5；在抛光过程中，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，移动速度范围为：4.5mm/s，使得抛光头能够加工整个光学玻璃表面；在进行该步骤抛光之前对步骤1磨抛后的光学表面面型轮廓进行检测，计算残余误差及材料去除量，并利用基于矩阵方程的驻留时间模型，计算出面型收敛所对应的驻留时间，完成第一次小磨头抛光工艺。然后重复上述参数，进行多次抛光，抑制光学表面的中、高频误差，抛光后表面误差小于λ/30(λ＝632.8nm)；由中心供液小磨头抛光工艺可有效去除固结磨料磨抛后表面形成的亚表面损伤层，抛光后残余的亚表面损伤层深度小于3μm。
在中心供液小磨抛抛光工艺过程中，抛光液从中心孔均匀分布于抛光盘表面，随着抛光盘的旋转抛光垫与抛光表面之间形成均匀的液膜间隙，此时抛光垫与工件表面介于半接触与非接触之间；液膜间隙内抛光颗粒在抛光工具的驱动下划擦光学表面以达到抛光的目的；在抛光过程中通过控制抛光液供给压力、抛光工具的转速以及抛光工具上的轴向载荷，用以控制液膜间隙的形成和材料的去除率。
步骤3、盘式流体动压抛光：将上述抛光后的光学玻璃进行清洗；从抛光盘3上揭下将中心供液小磨头抛光皮502，将盘式流体动压抛光垫503通过弹性粘接层4粘接到抛光盘3表面，使用浓度为10％的氧化铈作为抛光液，将抛光液以1.5Mpa的压力注入中心供液孔；通过旋转轴6对抛光盘3施加抛光盘施加轴向50N载荷，同时抛光盘以3000r/min速度自转，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，抛光工具移动速度为2mm/s，使得抛光头能够匀化加工整个光学玻璃表面，然后重复进行多次抛光，抑制光学表面的高频误差，抛光后表面残余误差小于1nm；亚表面损伤层深度小于1μm。
在盘式流体动压抛光垫抛光过程中，抛光液从中心孔沿着抛光盘表面动压槽均匀分布于抛光盘表面，随着抛光工具的高速旋转，抛光垫与抛光表面之间形成均匀的液膜间隙，此时抛光垫与工件表面处于非接触状态，依靠液膜间隙内的流体动压力驱动所述抛光液中的抛光颗粒冲蚀工件表面、抛光加工表面材料；抛光盘表面动压槽能够有效提要液膜间隙内流体动压力，从而提高抛光效率；在抛光过程中通过控制抛光液供给压力、抛光工具的 转速以及抛光工具上的轴向载荷，用以控制液膜间隙内的流体动压力，实现超光滑表面的加工工艺。
综上所述，应用子孔径中心供液光学表面系列加工工艺对磨削后光学表面在不同频段内误差控制及亚表面损伤抑制示意图如图7和图8所示。经过上述三种工艺的加工，从磨削后光学表面应用流体动压固结磨料磨抛工艺降低光学表面低频和部分中频误差，同时将亚表面损伤层深度降低至5μm以下；然后应用中心供液下磨头抛光工艺降低光学表面中频和部分高频误差，亚表面损伤层深度降低至3μm以下；最后应用盘式流体动压抛光工艺降低光学表面高频误差，亚表面损伤层深度降低至1μm以下。本发明工艺方法不仅能够在全频域内有效抑制光学表面误差，而且在加工过程中有效控制表面及亚表面损伤，图7是本发明光学加工工艺表面全频段误差控制示意图；图8是本发明光学加工工艺亚表面损伤抑制示意图，磨削后的光学元件表面分别经过流体动压固结磨料磨抛工艺、中心供液小磨头抛光工艺、盘式流体动压抛光工艺，逐层降低光学元件亚表面损伤层深度。
尽管上面结合附图对本发明进行了描述，但是本发明并不局限于上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制性的，本领域的普通技术人员在本发明的启示下，在不脱离本发明宗旨的情况下，还可以做出很多变形，这些均属于本发明的保护之内。

Claims (7)

  1. 一种子孔径中心供液光学表面加工工具，其特征在于，该工具包含有弹性联轴器(1)、抛光盘(3)和抛光垫(5)，所述抛光盘(3)一端为连接轴段，所述抛光盘(3)的另一端为盘面，所述柔性联轴器(1)的一端连接有旋转轴(6)，所述柔性联轴器(1)的另一端与所述抛光盘(3)连接，所述抛光盘(3)的盘面上通过弹性粘接层(4)与所述抛光垫(5)粘接，所述抛光垫(5)用于磨抛和抛光加工，所述抛光垫(5)的类型是固结磨料抛光垫(501)、中心供液小磨头抛光皮(502)以及盘式流体动压抛光垫(503)中的一种；根据不同的加工工艺要求更换不同类型的抛光垫，以达到光学元件表面工艺设计的需求，实现光学元件表面从粗到精的系统加工工艺；贯穿于所述旋转轴(6)、所述抛光盘(3)、所述弹性粘接层(4)和抛光垫(5)的轴向设有中心供液孔(500)；使用该工具时，该工具装夹于具有中心供液功能的电机或者抛光执行器上，所述电机或者抛光执行器的供液导管与所述中心供液孔(500)导通，通过电机驱动所述旋转轴(6)，从而使该工具自转或行星运动。
  2. 根据权利要求1所述的子孔径中心供液光学表面加工工具，其特征在于，所述固结磨料磨抛垫(501)中含有的磨抛颗粒是金刚石、氧化铈和氧化铝磨抛颗粒的其中一种或几种混合磨抛颗粒，所述磨抛颗粒的粒径范围为0.1～10μm。
  3. 根据权利要求1所述的子孔径中心供液光学表面加工工具，其特征在于，所述中心供液小磨头抛光皮(502)是多孔聚氨酯抛光片、阻尼布、海绵抛光片和合成纤维制成的抛光片中的任何一种；所述中心供液小磨头抛光皮(502)的工作表面具有导流槽。
  4. 根据权利要求1所述的子孔径中心供液光学表面加工工具，其特征在于，所述盘式流体动压抛光垫(503)的材质是软质金属或是抛光沥青。
  5. 根据权利要求4所述的子孔径中心供液光学表面加工工具，其特征在于，所述盘式流体动压抛光垫(503)的表面设计有动压槽，当所述盘式流体动压抛光垫(503)高速旋转、抛光液从中心供液孔(500)注入时，所述盘式流体动压抛光垫(503)与工 件的抛光加工表面之间形成稳定的动压液膜，依靠液膜间隙内的流体动压力驱动所述抛光液中的抛光颗粒冲蚀工件表面、抛光加工表面材料以达到超精密抛光工艺的目的。
  6. 一种子孔径中心供液光学表面系列加工工艺，其特征在于，所用的加工工具是如权利要求1至5任一所述的子孔径中心供液光学表面加工工具，包括流体动压固结磨料磨抛、中心供液小磨头抛光以及盘式流体动压抛光。
  7. 根据权利要求6所述的子孔径中心供液光学表面系列加工工艺，其特征在于，具体步骤如下：
    步骤1、流体动压固结磨料磨抛：将粘接有固结磨料磨抛垫(501)的加工工具装夹于具有中心供液功能的电机或者抛光执行器上，调整磨抛垫的表面与待加工工件表面接触；将研磨液注入工具的中心供液孔(500)内，由旋转轴(6)驱动磨抛盘(3)转动，转速范围50-1000rpm；在转动的同时在旋转轴(6)上施加载荷，载荷范围10～50N；控制加工工具的路径，按照栅格轨迹移动，移动速度范围为0.5～5mm/s；改变加工工具的进给路径对工件表面进行多轮加工，经过1～3轮加工，抑制光学表面的低频和中频误差；
    步骤2、中心供液小磨头抛光：将磨抛后表面进行清洗；将加工工具上的磨抛垫更换为中心供液小磨头抛光皮(502)，使用浓度为5％～15％的氧化铈或氧化铝抛光液，将抛光液以一定压力注入中心供液孔(500)，抛光液供给压力范围为：0.1～0.5Mpa；通过旋转轴(6)对抛光盘(3)施加10～30N的轴向载荷，并且抛光盘(3)以200～2000r/min速度自转，50～200rpm的速度公转，抛光盘公转/自转的偏心率为0.1～1.0；在抛光过程中，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，移动速度范围为：0.1～10mm/s，使得抛光盘能够加工整个加工表面，完成第一次小磨头抛光工艺；然后按照上述参数，重复进行多次抛光，抑制光学表面的中频和高频误差；
    步骤3、盘式流体动压抛光：将抛光后表面进行清洗；将加工工具上的磨抛垫更换为盘式流体动压抛光垫(503)，将浓度为5％～20％的氧化铈或氧化铝抛光液，将抛光液以一定压力注入中心供液孔(500)，抛光液供给压力范围为：0.5～2Mpa；通过旋转轴(6)对抛光盘(3)施加20～50N的轴向载荷，同时抛光盘以1000-8000r/min速度自转，控制抛光盘抛光路径按照栅格轨迹或者随机轨迹移动，抛光工具移动速度范围为：1～10mm/s，使得抛光盘能够匀化加工整个加工表面，完成第一次小磨头抛光工艺；然后按照上述参数，重复进行多次抛光，抑制光学表面的高频误差；至此实现超光滑表面的加工。
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