EP2353781A2 - Outil pour le lissage ou le polissage de surfaces optiques - Google Patents

Outil pour le lissage ou le polissage de surfaces optiques Download PDF

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Publication number
EP2353781A2
EP2353781A2 EP11152330A EP11152330A EP2353781A2 EP 2353781 A2 EP2353781 A2 EP 2353781A2 EP 11152330 A EP11152330 A EP 11152330A EP 11152330 A EP11152330 A EP 11152330A EP 2353781 A2 EP2353781 A2 EP 2353781A2
Authority
EP
European Patent Office
Prior art keywords
tool
tool according
piston
pad
optical surface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11152330A
Other languages
German (de)
English (en)
Other versions
EP2353781A3 (fr
Inventor
Colin Williams
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Qioptiq Ltd
Original Assignee
Qioptiq Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Qioptiq Ltd filed Critical Qioptiq Ltd
Publication of EP2353781A2 publication Critical patent/EP2353781A2/fr
Publication of EP2353781A3 publication Critical patent/EP2353781A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • B24B13/0018—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor for plane optical surfaces
    • 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
    • B24B13/012—Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools conformable in shape to the optical surface, e.g. by fluid pressure acting on an elastic membrane
    • 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
    • B24B13/02—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor by means of tools with abrading surfaces corresponding in shape with the lenses to be made

Definitions

  • the present invention relates to a tool for smoothing or polishing optical surfaces.
  • the invention is particularly suited to smoothing aspheric and freeform optical surfaces.
  • Figure 1 illustrates in schematic form a typical chain of process steps used in the production of high quality optics having spherical or flat optical surfaces. Initially, the surface of the lens or mirror is ground so as to conform closely to the desired surface profile. The grinding step is then followed by a smoothing step which is effective to remove surface errors such as ripples or waviness (so-called "mid-spatial" features) arising from the initial grinding step, and to provide a finely smoothed surface preparatory for the next step of polishing.
  • a smoothing step which is effective to remove surface errors such as ripples or waviness (so-called "mid-spatial" features) arising from the initial grinding step, and to provide a finely smoothed surface preparatory for the next step of polishing.
  • a tool for smoothing or polishing an optical surface comprising: a body part which is rotatable about an axis of rotation; a plurality of pistons mounted for individual reciprocating movement relative to the body part along respective longitudinal axes, each of said pistons having a distal end to which a respective pad is universally articulated, said pads being arranged in an array to bear against said optical surface for movement across the surface as the tool is rotated about said axis of rotation, wherein said pistons are each biased towards said optical surface along their respective longitudinal axes.
  • each said piston is spring-biased towards said optical surface.
  • each said piston is biased towards said optical surface by a respective spring.
  • each said spring is a compression spring.
  • the spring constant of each spring is determined in dependence on the radial distance of the respective piston from the axis of rotation of the tool.
  • the spring constants of the individual springs are inversely proportional to the radial distance of the respective pistons from the axis of rotation of the tool.
  • each said piston is mounted for sliding movement within a respective bore, and comprises at least one internal flow conduit in fluid communication with an outlet port provided in the piston to direct lubricating fluid between the piston and the bore.
  • the internal flow conduits are all provided in fluid communication with a plenum chamber within the body part.
  • the plenum chamber is supplied with lubricating fluid via a flow channel which is substantially coaxial with the axis of rotation of the body part.
  • said lubricating fluid is compressed air.
  • each pad is mounted to the distal end of the respective piston via a ball joint.
  • each ball joint comprises flexible adhesive to secure the pad to the piston.
  • each pad is mounted to the distal end of the respective piston via a spherical bearing.
  • said pads are arranged in a substantially planar array.
  • pads may be arranged in either a substantially convex array, or a substantially concave array.
  • each pad is substantially circular in shape.
  • a tool of the type defined above for smoothing or polishing an optical surface having a predefined surface profile to remove or reduce surface waves, wherein each pad is configured so as to have a diameter which is greater than the wavelength of the surface waves.
  • FIG. 3 there is illustrated a surface form measurement plot for a workpiece after an initial grinding step, but before any other processing has been performed.
  • the optical surface is denoted by the plot line 1.
  • the surface 1 has an underlying profile shape on which is superimposed a surface error feature of relatively small wavelength, as represented by the series of closely spaced peaks 2 and troughs 3.
  • the mean wavelength of the surface error is represented schematically at 4.
  • the tool of the present invention is effective to produce a surface profile similar to that shown in figure 4 , by removing the surface error 2, 3 in the profile shown in figure 3 , and is particularly suitable for use on aspheric or free-form surface profiles.
  • the tool head comprises a body part 6 which is preferably formed from stainless steel, and comprises an elongate central shank 7 which is centred on a central axis of rotation 8. At its upper end, the shank 7 is configured to be engaged with an actuating mechanism (not shown) operable to rotate the tool body 6 about the axis 8, and also to move the tool head in an appropriate oscillatory manner generally known per se in the field of smoothing and lapping tools.
  • actuating mechanism not shown
  • An integrally formed circular flange 9 extends radially outwardly from the lower end of the shank 7, and has a small downwardly directed lip 10 formed around its periphery.
  • the lip 10 defines a planar annular engaging surface 11.
  • a circular cover plate 12 is provided, which is again preferably formed of stainless steel and which is of substantially equal diameter to the flange 9.
  • the cover plate 12 has a small upwardly directed lip 13 formed around its periphery which defines a planar annular engaging surface 14 configured for mating engagement with the similar surface 11 of the downwardly directed lip 10.
  • the cover plate 12 is affixed to the flange 9 such that the two surfaces 11, 14 are brought into engagement with one another in the manner illustrated in figure 5 .
  • a small circular plenum chamber 15 is defined between the flange 9 and the cover 12.
  • the plenum chamber 15 is provided in fluid communication with a central flow channel 16 which extends along the length of the shank 7 and which is substantially coaxial with the axis of rotation 8.
  • the flow channel is used to feed a supply of lubricating fluid, most preferably compressed air, to the plenum chamber for reasons that will be explained in more detail hereinafter.
  • the cover plate 12 is provided with a plurality of substantially cylindrical bores 17, each of which extends fully from one side of the plate to the other.
  • the bores 17 are arranged in a generally circular array so as to cover the major extent of the cover plate 12.
  • each piston 18 is thus mounted for individual reciprocating movement relative to the tool body 6 along a respective axis 19.
  • the axes 19 of all of the pistons are parallel.
  • FIG. 6 illustrates a single piston 18 in greater detail.
  • Each piston 18 is generally cylindrical in form, having a proximal end 20 and a distal end 21, and is preferably formed from either phosphorous bronze or brass.
  • the main part of the cylindrical piston has a diameter slightly less than the diameter of its corresponding bore 17, so as to form a close sliding fit within the bore.
  • each piston 18 is provided with a small outwardly directed retaining lip 22 which has a diameter greater than the diameter of the bore 17. As shown in figure 5 , the retaining lip of each piston 18 is received within the plenum chamber 15 when the cover plate 12 and the flange 9 are connected, and thus serves to prevent the piston falling out of its respective bore 17, effectively holding the piston captive with respect to the tool body 6.
  • each piston is provided with a central recess 23, the recess being of generally cylindrical form and centred on the longitudinal axis 19 of the piston.
  • the recess 23 of each piston receives the lower end of a respective biasing spring 24.
  • the biasing springs are helically wound compression springs, and are preferably formed from stainless steel.
  • each piston carries a smoothing/polishing pad 26.
  • Each pad 26 is preferably circular in form and comprises a substantially rigid plate (preferably formed of aluminium), and presents a downwardly directed planar smoothing/polishing surface 27.
  • the surfaces 27 of the pads 26 may be provided with a thin coating of polyurethane or similar material for polishing purposes, thereby allowing the tool to be used for polishing.
  • the surfaces 27 may be provided with a thin layer of abrasive material, for example comprising diamond, thereby making the tool suitable for smoothing purposes.
  • Each pad 26 is universally articulated to the distal end of its respective piston, so as to be mounted for substantially universal pivotal movement relative to the tool body 6, about the end of the piston.
  • This universal articulation may be achieved in a number of alternative ways, but is most preferably provided by way of a so-called ball joint.
  • the distal end of each piston is provided with a downwardly projecting ball 28 which is received in a corresponding socket 29 formed on the upper side of the respective pad 26.
  • Each pad 26 is secured to the distal end of its respective piston 18 via an annular fillet 30 of flexible adhesive (such as silicone adhesive) extending around the ball 28, the fillet being sufficiently pliable so as not to interfere substantially with the universal pivotal movement of the pad.
  • the size of the pads 26 is carefully selected, in dependence on characteristics of the optical surface on which the tool is to be used. This will be explained in more detail hereinafter.
  • each piston 18 is also provided with a system of internal flow conduits. More particularly, each piston comprises a central flow conduit 31 which runs downwardly from an open end 32 provided within the recess 23, towards the distal end 21.
  • the central flow conduit 31 is coaxial with the longitudinal axis 19 of the piston and terminates approximately mid-way between the two ends of the piston, at which point a pair of oppositely-directed radial conduits 32 extend outwardly, terminating with respective outlet ports 34 provided in the external surface of the piston.
  • the flow conduits 32, 33 within each piston are provided in fluid communication with the plenum chamber 15, and hence receive a flow of lubricating fluid (preferably compressed air), and direct the lubricating fluid to the outlet ports 34, so as to provide a thin film of lubricating fluid between the outer surface of the pistons 18 and their respective bores 17. It is proposed that during use of the tool, the lubricating fluid will be maintained at an elevated pressure within the plenum chamber, such that there is a substantially constant flow of fluid through the outlet ports, thereby expelling any polishing slurry or machine coolant which may otherwise penetrate the tool.
  • a flow of lubricating fluid preferably compressed air
  • the above-described tool presents an array of smoothing/polishing pads 26 to bear against the target optical surface 35 of the workpiece 25.
  • Each pad is mounted for substantially linear movement along a respective piston axis 19, and thus in a direction substantially normal to the optical surface 35 in the region where the pad contacts the surface 35.
  • Each pad is also mounted for universal movement relative to the tool body, and is also biased towards the tool body.
  • the pads are thus arranged so as to move independently of one another and to remain in substantially intimate contact with the surface 35, as the tool is rotated about its axis 8 and moved in an oscillatory manner across the surface 35. Together, the pads thus present a significant area of smoothing/polishing surface to the workpiece.
  • FIG. 7 illustrates in more detail the articulation of the pads 26 and their size relative to the features of the target surface 35.
  • Two alternate pad positions are shown at a) and b).
  • the diagram also shows the surface error "waviness" as represented by the small peaks 2 and troughs 3, and the underlying surface profile curve 5.
  • each pad has a diameter D which is greater than the wavelength 4 of the surface error pattern. This ensures that the pads 26 always ride over the waves of the surface error feature such that their movement relative to the surface is effective to smooth out the error feature.
  • each pad 26 is shown in a tilted position effective to conform generally to the local curvature of underlying surface profile1.
  • each pad is mounted for individual linear and pivotal movement, all the pads remain substantially in contact with the target surface as the tool head is moved across the surface.
  • the maximum permissible pad diameter will be calculated empirically in dependence on factors such as the tightest radius of curvature of the surface profile 1, the grain size of any polishing or smoothing compound used, and other operating factors such as rotational speed, oscillation speed, and pressure.
  • each spring 24 be individually tailored to the relative position of the spring and its associated pad within the overall array of pads.
  • the springs 24 biasing the peripheral pads 26 towards the workpiece will have a smaller spring constant than those arranged to bias pads located more centrally within the array.
  • each spring 24 is determined in dependence on the radial distance of the respective piston 18 from the central axis of rotation 8 of the tool. More particularly, it is proposed that the spring constants of the individual springs 24 are inversely proportional to the radial distance of their respective pistons 18 from the axis of rotation 8 of the tool.
  • the tool of the present invention has been described above with specific reference to an embodiment in which the flange 9 and the associated cover plate 12 are generally planar, and in which the pistons are all arranged for reciprocating movement along parallel axes 19.
  • the pads 26 are thus arranged in a generally planar array.
  • the pads may be arranged either in a generally convex array (as illustrated in figure 8 ), or a generally concave array (as illustrated in figure 9 ) for use in smoothing or polishing a generally concave or convex workpiece respectively.
  • the variant illustrated in figure 8 is configured such that the pistons 18 are mounted for reciprocating movement along axes 19 which are divergent in the sense that they diverge with increasing distance away from the upper end of the spindle 7.
  • the variant illustrated in figure is configured such that the pistons 18 are mounted for reciprocating movement along axes 19 which are convergent in the sense that they converge with increasing distance away from the upper end of the spindle 7.
  • the tool may alternatively be used with a liquid lubricant.
  • the tool body 6 has been described above as preferably being made from stainless steel, other materials are also suitable.
  • the body may be made from aluminium, or even plastics materials.
  • the pistons 18 need not necessarily be made from phosphorous bronze or brass, and could instead be made from other convenient materials such as low friction or self-lubricating materials (e.g. Nylon or PTFE).
  • FIG 10 illustrates a tool in accordance with another proposal, as viewed from below showing the array of individual smoothing/polishing pads 26.
  • the cover plate 12 of the embodiment described above has effectively been replaced with a circular membrane or diaphragm 36 formed of resiliently deformable material such as an elastomer.
  • the membrane is affixed to the flange 9 so as to define a similar plenum chamber between the diaphragm and the flange.
  • the pads 26 are affixed directly to the outer surface of the membrane.
  • the membrane In its relaxed condition, the membrane can either be: substantially planar as illustrated in figure 10 (thereby presenting a planar array of pads similar to the arrangement of figure 5 ); convex (thereby presenting a convex array of pads similar to the arrangement of figure 8 ); or concave (thereby presenting a concave array of pads similar to the arrangement of figure 9 ).
  • the membrane is resiliently deformable, and has a degree of flexibility, it effectively serves the function of the individual pistons of the previously described arrangements by biasing the pads 26 towards the target optical surface and supporting the pads 26 for i) substantially linear movement relative to the body part 6 of the tool in a direction substantially normal to the target optical surface in the region where the pad contacts the surface, and ii) universal pivotal movement relative to the body part.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
EP11152330A 2010-02-08 2011-01-27 Outil pour le lissage ou le polissage de surfaces optiques Withdrawn EP2353781A3 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1002017A GB2477557A (en) 2010-02-08 2010-02-08 Aspheric optical surface polishing tool with individually movable polishing pads

Publications (2)

Publication Number Publication Date
EP2353781A2 true EP2353781A2 (fr) 2011-08-10
EP2353781A3 EP2353781A3 (fr) 2012-12-26

Family

ID=42082638

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11152330A Withdrawn EP2353781A3 (fr) 2010-02-08 2011-01-27 Outil pour le lissage ou le polissage de surfaces optiques

Country Status (3)

Country Link
US (1) US20110195645A1 (fr)
EP (1) EP2353781A3 (fr)
GB (1) GB2477557A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102581743A (zh) * 2012-02-21 2012-07-18 宁波大学 一种非球面光学零件的研抛方法
CN103231320A (zh) * 2013-04-16 2013-08-07 北京理工大学 一种用于曲面加工的多点支撑面型可调自锁式抛光盘
CN105150051A (zh) * 2015-07-28 2015-12-16 中国科学院长春光学精密机械与物理研究所 一种内联式多气缸自适应抛光磨头
CN105364641A (zh) * 2015-11-19 2016-03-02 浙江工业大学 微半环凹模阵列式研抛方法及装置

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Publication number Priority date Publication date Assignee Title
JP6071335B2 (ja) * 2011-09-05 2017-02-01 キヤノン株式会社 加工装置および光学部材の製造方法
DE102014109654B4 (de) 2014-07-10 2022-05-12 Carl Zeiss Jena Gmbh Vorrichtungen zum Bearbeiten von optischen Werkstücken
CN109202709A (zh) * 2018-11-21 2019-01-15 中国科学院光电技术研究所 一种气压控制恒定压力自适应抛光磨头
CN110202424B (zh) * 2019-06-27 2020-04-17 山东大学 一种贯通式微透镜阵列工件的仿形抛光方法
CN111633509B (zh) * 2020-06-04 2022-04-05 深圳市国林光学有限公司 虚拟现实用镜片抛光设备
CN111993215B (zh) * 2020-08-18 2022-06-14 中国科学院光电技术研究所 一种用于大口径光学元件加工的可变形柔性抛光工具
CN112454034A (zh) * 2020-11-24 2021-03-09 黄金仙 一种轴承生产加工用轴承圈生产装置
CN112571203A (zh) * 2020-12-07 2021-03-30 中国科学院长春光学精密机械与物理研究所 一种可变形研抛盘
CN114603430B (zh) * 2022-05-10 2022-08-19 中国科学院光电技术研究所 一种深型轴棱锥光学元件表面碎带误差抑制方法
CN116922243B (zh) * 2023-09-19 2023-11-28 苏州中砥半导体材料有限公司 一种基于磷化铟单晶的制备系统及制备方法

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JPS63232957A (ja) * 1987-03-19 1988-09-28 Canon Inc 曲面研摩機
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US5230184A (en) * 1991-07-05 1993-07-27 Motorola, Inc. Distributed polishing head
JPH09323249A (ja) * 1996-06-04 1997-12-16 Nikon Corp 研磨工具
JPH10286777A (ja) * 1997-04-09 1998-10-27 Nikon Corp 研磨工具皿
US6296550B1 (en) * 1998-11-16 2001-10-02 Chartered Semiconductor Manufacturing Ltd. Scalable multi-pad design for improved CMP process
WO2001056740A1 (fr) * 2000-02-03 2001-08-09 Carl Zeiss Tete de polissage pour une polisseuse

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102581743A (zh) * 2012-02-21 2012-07-18 宁波大学 一种非球面光学零件的研抛方法
CN103231320A (zh) * 2013-04-16 2013-08-07 北京理工大学 一种用于曲面加工的多点支撑面型可调自锁式抛光盘
CN105150051A (zh) * 2015-07-28 2015-12-16 中国科学院长春光学精密机械与物理研究所 一种内联式多气缸自适应抛光磨头
CN105364641A (zh) * 2015-11-19 2016-03-02 浙江工业大学 微半环凹模阵列式研抛方法及装置

Also Published As

Publication number Publication date
GB2477557A (en) 2011-08-10
GB201002017D0 (en) 2010-03-24
US20110195645A1 (en) 2011-08-11
EP2353781A3 (fr) 2012-12-26

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