JP2020025998A - Local polishing processing method, local polishing processing device, and corrective polishing processing device using the same - Google Patents

Abstract

To provide a local polishing processing technique which stabilizes the amount of local polishing processing, which can obtain high corrective spatial resolution, and which is suitable for corrective polishing processing.SOLUTION: Pressing polishing processing is performed while a polishing processing fluid, in which abrasive grains 81 composed of organic particles with an average particle diameter of 5 μm or more are dispersed in a liquid, is supplied between a workpiece 9 and a workpiece-polishing rotary tool 11 for being locally pressed against the workpiece 9. The rotary tool 11 is made of an elastic material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a local polishing method and a local polishing apparatus that can be suitably used for a modified polishing process.

  For example, in the processing of an optical element such as an optical lens, a rotary tool capable of locally polishing is supplied to a workpiece (coated) while a slurry-like polishing liquid comprising fine abrasive grains having an average particle diameter of about 1 μm is supplied therebetween. Correction polishing is performed in which the entire surface is scanned while being pressed against the workpiece. In the modified polishing process, a static processing mark is obtained by previously polishing a material of the same quality as the workpiece without scanning the rotating tool, and a unit processing shape in which the static processing mark is replaced per unit time is obtained. The unit processing shape and the shape error on the workpiece (corrected target shape) are deconvoluted (deconvolution integral) to calculate the dwell time (scanning speed) of the rotary tool, and along the dwell time distribution. Correction processing is performed to a target shape by a process of scanning a rotating tool (for example, see Patent Document 1).

  In the modified polishing process, since the scanning process is performed as described above, it is important that the local processing amount by the rotating tool is linear in time and stable for a long time. However, in the conventional correction polishing, there is a problem that a stable processing amount cannot be obtained because the rotating tool itself pressed locally against the work side is worn or the pressing force is apt to fluctuate. In addition, since the surface properties of the tool have a large effect on the transportation and retention of fine abrasive grains, and the discharge of chips, the rotating tool is polished after the surface properties are adjusted by pretreatment such as truing (shaping) and dressing (sharpening). However, such a pretreatment causes a decrease in processing efficiency and an increase in cost.In addition, as described above, since the rotating tool is easily worn, maintenance of the surface properties is also required frequently, and further efficiency is required. It causes a decrease and an increase in cost.

  On the other hand, in recent years, instead of positively pressing the rotating tool against the workpiece, a gap between the rotating tool and the workpiece that is equal to or greater than the diameter of the fine abrasive grains is maintained, and a slurry-like polishing process flowing therebetween. Non-contact EEM (Elastic Emission Machining), which performs precise polishing by chemical bonding and adhesion removal between fine abrasive grains in the liquid and the work surface, and polishing using a magnetic fluid tool are also being used. (For example, see Patent Document 2). However, these non-contact processing methods require a circulating device that thoroughly controls the viscosity and concentration of the polishing liquid, which tends to increase the size of the equipment and increase the speed of the slurry flowing through the gap. In order to achieve this, it is necessary to set the outer diameter of the outer peripheral surface of the rotating tool facing the work to be equal to or greater than a predetermined value, and also to set the rotation speed to be equal to or greater than a predetermined value.

  The spatial resolution that can be corrected in the correction polishing process is related to the size of the unit processing shape. For example, when correcting a waviness having a cycle of 1 mm, the correction cannot be performed unless the unit processing shape size is 1 mm or less. The currently widely used non-contact correction polishing apparatus is limited to a spatial resolution of about 1 mm. Further, even in the study of the modified polishing technique aiming at high resolution, it is up to about 0.3 mm. On the other hand, an optical element using a short-wavelength light source such as an X-ray is required to have a single-nanometer accuracy. However, in an X-ray optical element separately developed by the present inventors, a spatial wavelength of 0.1 to 0. The effect of a wavefront error caused by a swell area of about 3 mm has been confirmed. The non-contact correction polishing technique cannot cope with the correction of the undulation having a small spatial wavelength.

JP 2005-22005 A Japanese Patent Publication No. 2-25745

  In view of the above-mentioned situation, the present invention seeks to solve the above-mentioned problems by suppressing the cost with a simple structure, making the apparatus compact, stabilizing the processing amount by local polishing, and obtaining high spatial resolution. Another object of the present invention is to provide a local polishing technique suitable for the modified polishing.

  As a result of the inventor's intensive studies to solve the above-described problems, it is shown in FIG. 1A that the tool itself is worn or the influence of the tool surface property is increased in the conventional local polishing by pressing. As described above, since the rotating tool 11 is pressed against the work surface 90 of the work 9 via the fine abrasive grains 81 having an average particle diameter of 1 μm or less, the rotating tool 11 comes into direct contact with the work 9. As shown in FIG. 1B, when the abrasive grains 81 having a coarser average particle diameter of 5 μm or more are used, direct contact between the rotary tool 11 and the work 9 and wear of the rotary tool 11 due to the direct contact are prevented, and The surface properties did not affect the processing, and with the idea that the processing amount could be stabilized while keeping costs down with a simple structure, further studies were conducted.

  The inventor of the present invention first carried out press-polishing using a rotating tool using silica having an average particle diameter of 14 μm as polishing abrasive grains. As a result, processing stability was confirmed. However, there was a problem that the surface roughness after the polishing was greatly deteriorated (see the result of Comparative Example 1 of the raster scan processing test 1 described later).

On the other hand, it can be seen from the Stokes equation that the sedimentation velocity of the particles is proportional to the square of the particle diameter. That is, considering the use of abrasive grains having a particle diameter of 10 μm or more set this time, the dispersibility also becomes a bottleneck. Since the density of the abrasive particles normally used is 2 to 8 g / cm ^3, the solution of pure water (density 1 g / cm ³⁾ and to have more, it is difficult to improve the dispersibility. The aggregated silica actually used had poor dispersibility and was stable during circulation of the slurry, but was very difficult to handle in terms of storage and re-stirring.

  The present inventors deviate from the general term "polishing abrasive grains" based on metal oxides and metal carbides, and consider using monodisperse grains having an average grain size of 5 μm or more and having a small density as abrasive grains. As a result, the use of organic particles was conceived. For example, particles of a polymer material such as urethane, acrylic, and styrene are produced by an emulsion polymerization method. These have a substantially spherical shape, and a product having a particle size of 5 to 10 μm or more can be produced. Further, since the resin is a resin, various merits can be considered in the polishing process, such as low cost, low density, good dispersibility, and dissolving in an organic solvent such as acetone, so that the cleaning property after the polishing process is good.

  Then, as a result of actual pressing and polishing with acrylic particles (average particle size of 10 μm), excellent processing stability was obtained, and at the same time, processing that maintained the surface roughness was realized, and the present invention was completed.

That is, the present invention includes the following inventions.
(1) A polishing liquid in which abrasive grains composed of organic particles having an average particle size of 5 μm or more are dispersed in a liquid is supplied between the workpiece and a rotary tool for polishing the workpiece that is locally pressed against the workpiece. A local polishing method in which pressing and polishing is performed while performing. Here, the average particle size refers to a median size in a particle size distribution measured by a laser diffraction scattering method.

  (2) The local polishing method according to (1), wherein the rotating tool is made of an elastic material.

  (3) The local polishing method according to (1) or (2), wherein the liquid is pure water or a liquid containing water as a main component.

  (4) rotating the rotating tool, a rotating body, a rotating body provided at a distal end, an axially long rotating body for rotating the rotating body, and a rotating shaft about the axial center while supporting the rotating shaft at a base end side; The shaft is curved by pressing the outer peripheral surface of the rotating body against the work side, and the rotating body is pressed against the work side by the elastic restoring force of the curved shaft body. The local polishing method according to any one of (1) to (3).

  (5) The local polishing method according to any one of (1) to (4), wherein the outer diameter of the polishing area on the outer peripheral surface of the rotary tool facing the work is set to 5.0 mm or less.

  (6) The local polishing method according to any one of (1) to (5), wherein the organic particles are acrylic particles or urethane particles.

  (7) A rotating tool for polishing a workpiece that is locally pressed against the workpiece, and a polishing process in which abrasive grains composed of organic particles having an average particle size of 5 μm or more are dispersed in the liquid between the rotating tool and the workpiece. A local polishing processing apparatus, comprising: a processing liquid supply unit configured to supply a liquid.

  (8) The local polishing apparatus according to (7), wherein the rotating tool is made of an elastic material.

  (9) The local polishing apparatus according to (7) or (8), wherein the liquid is pure water or a liquid containing water as a main component.

  (10) The rotating tool includes a rotating body, a rotating body provided at a distal end thereof, an axially long shaft body for rotating the rotating body, and a rotation about the axial center while supporting the shaft body at a base end side. The shaft body is curved by pressing the outer peripheral surface of the rotating body against the work side, and the rotating body is pressed against the work side by the elastic restoring force of the curved shaft body. The local polishing apparatus according to any one of (7) to (9).

  (11) The local polishing apparatus according to any one of (7) to (10), wherein an outer diameter of a polishing action area on an outer peripheral surface of the rotary tool facing the work is 5.0 mm or less.

  (12) The local polishing apparatus according to any one of (7) to (11), wherein the organic particles are acrylic particles or urethane particles.

  (13) A modified polishing apparatus using the local polishing apparatus according to any one of (7) to (12).

  According to the present invention described above, the wear of the rotating tool is prevented in the local pressing and polishing, the surface properties of the tool do not affect the processing, and the pretreatment and maintenance of the tool surface can be omitted. . In addition, it is possible to realize local polishing that can achieve excellent processing stability while maintaining surface roughness while suppressing costs with such a simple structure, and can be suitably used as modified polishing.

  Further, when the rotating tool is made of an elastic material, the rotating tool is polished by the rolling operation of the abrasive grains between the rotating tool and the work, so that the surface roughness can be further improved and the rotating tool can be rotated. The pressing force is stabilized by the elastic deformation of the tool, and the processing stability can be further improved.

  Further, when the liquid for dispersing the organic particles as abrasive grains is pure water or a liquid containing water as a main component, the dispersibility of the organic particles is improved, the processing stability is further improved, and the work is made of silicon. In the case of glass or glass, since a soft hydrated film is formed on the surface by water, the removal process is further promoted and the surface roughness can be improved.

  Also, a rotating tool, a rotating body, a rotating body provided with the rotating body at the distal end, a shaft body that is long in the axial direction for rotating the rotating body, and a rotation for rotating the rotating body about the shaft while supporting the shaft body at the base end side. The shaft is bent by pressing the outer peripheral surface of the rotating body against the work, and the elastic body is pressed against the work by the elastic restoring force of the curved shaft. In this case, the pressing force of the rotating tool is stabilized, and the processing stability can be further improved.

  Further, when the outer diameter of the polishing action area on the rotating outer peripheral surface facing the work of the rotating tool is set to 5.0 mm or less, local polishing with higher resolution can be performed.

FIG. 3 is an explanatory diagram for explaining a processing principle. FIG. 1 is a front view showing a local polishing apparatus according to a representative embodiment of the present invention. FIG. 2 is a perspective view of the local polishing apparatus as viewed obliquely from below. Explanatory drawing which shows the principal part of the local polishing apparatus similarly. FIG. 6 is a front view showing a local polishing apparatus according to another embodiment. Explanatory drawing which shows the principal part of the local polishing apparatus similarly. Explanatory drawing which shows the principal part of a rotating tool. 4 is a surface observation image of a static processing trace according to the first embodiment. 16 is a surface observation image of a still machining trace according to the eighth embodiment. 19 is a surface observation image of a still machining trace according to the ninth embodiment. 9 is a surface observation image of a static processing trace according to Comparative Example 1. 5 is a graph illustrating a relationship between a processing amount and a processing time according to the first embodiment. 7 is a graph showing a relationship between a processing amount and a processing time according to Comparative Example 1. FIG. 4 is an explanatory view showing a method of a raster scan processing test. 9 is a surface observation image showing a raster scan processing result according to Comparative Example 1. Surface observation image showing surface roughness before raster scan processing. 4 is a surface observation image showing the surface roughness after raster scan processing according to Example 1. 9 is a surface observation image showing the surface roughness after raster scan processing according to Example 2. 18 is a surface observation image showing the surface roughness after raster scan processing according to Example 8. 9 is a surface observation image showing the surface roughness after raster scan processing according to Comparative Example 1. 9 is a surface observation image showing the surface roughness after raster scan processing according to Comparative Example 2. 4 is a graph showing the relationship between the processing amount and the pressing force on the synthetic quartz glass substrate of Example 1. 4 is a graph showing the relationship between the amount of processing and the pressing force on the silicon substrate of Example 1. 4 is a surface observation image showing a result of raster scan processing performed on a silicon substrate according to the first embodiment. 5 is a graph showing the relationship between the amount of processing and the particle size of abrasive grains. 5 is a graph showing a relationship between a processing amount and an abrasive concentration. The figure which shows the ideal processing result (ideal processing amount calculation result) by the modified polishing test 1, and the surface observation image which shows the actual processing result. FIG. 5 is a comparison diagram of a horizontal center cross-sectional profile (amount of processing) between an ideal processing result and an actual processing result by the modified polishing test 1; Surface observation images showing the surface roughness before and after the modified polishing test 1. The figure which shows the ideal processing result (ideal processing amount calculation result) by the modified polishing test 2, and the surface observation image which shows the actual processing result. Surface observation images showing the surface roughness before and after the modified polishing test 2.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 2 to 4, a local polishing apparatus 1 according to a representative embodiment of the present invention includes a rotating tool 11 for polishing a workpiece that is locally pressed against a workpiece 9, A work fluid supply means 12 is provided between the work 9 and the work fluid to supply a polishing work fluid 8 in which abrasive grains made of organic particles having an average particle size of 5 μm or more are dispersed in a liquid.

  As shown in FIG. 1 (b), the processing principle is such that the abrasive grains 81 in the polishing liquid 8 supplied between the rotating tool 11 and the work 9 are rolled on the surface of the work 9 while being sandwiched between the polishing tools. Nine surfaces are polished. Therefore, the polishing action area of the outer peripheral surface of the rotary tool 11 facing the work 9 does not need to have a uniform surface property, and in this example, is configured using an elastic body made of an elastic material that can more easily capture the abrasive grains 81. .

  The apparatus shown in FIGS. 2 to 4 is configured as an apparatus of a type for polishing a plate-shaped work 9, and holds the work 9 with the work surface 90 facing downward movably in the XYZ directions at an upper position. The work holding mechanism 13 (X-axis stage 41, Y-axis stage 42, Z-axis stage 43) is provided. At a position almost directly below the work 9 held by the work holding mechanism 13, as the working liquid supply means 12, a jet is provided for injecting the polishing working liquid 8 directly above with a gap s 1 into which the rotary tool 11 is inserted. The machining liquid ejection unit 14 having the nozzle 30 is provided.

  In the present example, the work surface 90 of the plate-shaped work 9 is a plane, but even if it is a curved surface such as a lens, the work holding mechanism 13 can move the work 9 three-dimensionally. If the work holding mechanism 13 is provided with a rotation mechanism (rotary stage; θ stage) for rotating the work 9 while holding it, the posture can be changed in addition to the position of the work, and the degree of freedom of processing can be further increased. Can be.

  In this example, the support table 23 that supports the rotary tool 11 in an inclined state further includes a mechanism that supports the rotary support section 22 so that the angle can be adjusted, and can more flexibly correspond to the shape of the work surface 90. , The degree of freedom of processing is increased. By automatically controlling the operations of the work holding mechanism 13 and the support table 23 by a computer (not shown), the apparatus can be used as a modified polishing apparatus that automatically scans a surface to be processed.

  The machining liquid ejecting unit 14 as the machining fluid supply unit 12 receives the ejection nozzle 30 and the polishing machining liquid 8 ejected from the nozzle and coming into contact with the workpiece surface 90 and collecting around the ejection nozzle 30. The polishing tank 8 comprises a tank 31 and a pump 35 for supplying the polishing liquid 8 received and collected in the collecting tank 31 again to the jet nozzle 30 and jetting the polishing liquid upward. The circulation is performed between 30, the work surface 90, the recovery tank 31, and the pump 35.

  In this way, the polishing liquid 8 is jetted and supplied to the work surface 90 by the processing liquid jet unit 14, so that the polishing liquid 8 can be stably and efficiently supplied to a local polishing region of the work surface 90. Can be supplied, and stable polishing can be performed for a long time with a small amount of polishing liquid. In addition, it can be used regardless of the shape and size of the work, which contributes to cost reduction. In particular, by injecting in the form of a fountain from directly below, the polishing liquid 8 can be supplied uniformly in all directions, so that the processing rate is more stable and the amount of water can be reduced.

  The rotating tool 11 is made of an elastic material. Specifically, a rotating body 20 made of an elastic material such as rubber, the rotating body 20 is provided at the distal end, a shaft body 21 that is long in the axial direction for rotating the rotating body 20, and the shaft body 21 at the base end side. And a rotation support portion 22 that rotates the shaft 21 while supporting it. When the outer peripheral surface of the rotating body 20 is pressed against the work 9, the shaft 21 is curved, and the rotating body 20 is pressed against the work 9 by the elastic restoring force of the curved shaft 21.

  As shown in FIG. 7, the rotating body 20 is preferably configured such that the outer diameter d2 (maximum diameter in the area) of the polishing action area 201 on the outer peripheral surface 20a facing the workpiece 9 is 5.0 mm or less, The diameter of the rotating body (the maximum diameter of the outer peripheral surface) is set smaller than the diameter of the conventional rotating tool. As the shape of the rotating body 20, various shapes such as a spherical shape, a partial spherical shape, a ring shape with a circular cross section (toroidal shape), and the like can be adopted. Then, the abrasive grains interposed between the rotating body 20 and the workpiece processing surface 90 roll on the processing surface 90 while being pressed by the rotating body 20 to polish the processing surface 90, thereby reducing the surface roughness. Make it better.

  Since the rotating body 20 is made of an elastic material as described above, the pressing force for pressing the work surface 90 via the abrasive grains 81 is stabilized, and the abrasive grains 81 are firmly held and rolled on the work surface 90. And the processing stability is improved. As a specific elastic material, it is preferable to use fluoro rubber. Fluororubber has the advantage that it has a low coefficient of friction and is a chemically stable substance when the pH of the working fluid is adjusted.

  Further, since the rotating body is set to have a small diameter as described above, a force for locally pressing the work processing surface 90 side is exerted, and the energy for pressing the abrasive grains per unit area with respect to the intervening abrasive grains is increased. It is thought that the processing rate will increase and the processing rate will also increase. In addition, a small unit processing shape can be obtained, and excellent spatial resolution can be obtained.

  As the shaft body 21, a metal shaft such as stainless steel having a cross section smaller in diameter than the rotating body 20 can be used. Of course, other materials may be used as long as they are long and flexible in the axial direction. In this example, the rotating tool 11 is configured by fitting the distal end portion of the shaft body 21 into the toroidal-shaped rotating body 20 and fixing the same, and fixing the base end portion of the shaft body 21 to the rotation supporting section 22. I have. An electric motor or the like can be used for the rotation support section 22.

  The shaft body 21 extends obliquely from a position obliquely below the gap s1 between the work 9 and the nozzle 30 so that the rotating body 20 at the tip is pressed against the processing surface 90 side. The base end is rotatably supported by a rotation support portion 22 provided at the lower position. In this example, the axial direction of the shaft body (when slightly curved by pressing against the work, the axial direction at the position of the tip where the rotating body is provided) is approximately 45 degrees with respect to the normal line of the processing surface 90. , But is not limited to this angle. By adopting a structure in which the rotating body 20 is inserted into the gap s1 by the shaft 21 from diagonally below as in this example, when the surface to be processed is a curved surface (for example, a free curved surface), the workpiece is rotated and processed. Also becomes easier. If the shaft body 21 is arranged parallel to the processing surface 90, it becomes difficult to rotate and work the workpiece in this manner.

  As in this example, by using the flexible shaft body 21 and processing the rotary body 20 while pressing and pressing the rotating body 20 against the work 9 by the elastic restoring force of the curved shaft body 21, Even if the positional relationship between the rotary tool 11 and the workpiece 9 is slightly shifted depending on the shape, the shaft body 21 is only elastically deformed by that amount, so that the pressing force can be prevented from largely fluctuating, and the pressing force is made substantially constant. By keeping it, a stable processing amount can be obtained. This means that the precision required for the stages 41, 42, 43 (work holding mechanism 13) and the like can be suppressed (for example, the precision of about 10 μm is also required for the correction polishing at the nano level of the lens).

The liquid of the polishing liquid 8 is preferably pure water or a liquid containing water as a main component in view of the dispersibility of the organic particles. As the organic particles, various types can be employed. In particular, those having a density close to 1 g / cm ³ such as acrylic particles, urethane particles, and styrene particles made of a polymer material are preferable. Among them, urethane / acryl (both having a density of 1.2 g / cm ³ ) is more preferable. Organic particles have a density close to 1 g / cm ³ and are easily dispersed without precipitation, as compared with metal oxide particles which are general abrasives. Organic particles of different materials may be mixed.

  The average particle size of the organic particles is preferably 5 μm or more and 30 μm or less.

  Next, based on FIGS. 5 and 6, the shape of a rotating body such as the outer peripheral surface of a cylindrical work such as a rod lens, the outer peripheral surface of a conical or frustoconical work, and the inner / outer peripheral surface of a cylindrical work will be described. An embodiment of another apparatus configuration according to the present invention, which is suitable when the surface (rotation surface) of the work is the surface to be processed, will be described.

  The local polishing apparatus 1 </ b> A according to the present embodiment includes a rotating tool 11 locally pressed against a workpiece 9, and a rotating tool 11 and the workpiece 9 between the rotating tool 11 and the workpiece 9, similarly to the apparatus 1 according to the representative embodiment described above. A machining fluid supply means 12 for supplying a polishing fluid 8 in which abrasive grains composed of organic particles having an average particle diameter of 5 μm or more are dispersed in a liquid, and polishes the surface of the work 9 by the same machining principle.

  The work holding mechanism 13 is provided with a mechanism for rotating a columnar or cylindrical work around an axis together with an XYZ stage (not shown). In the processing of the inner or outer peripheral surface of a cylindrical or cylindrical work, it is not necessary to move the work largely horizontally, so in this embodiment, the working liquid supply means 12 has an upper end opening for storing the polishing liquid 8. While the processing tank 32 is provided, the work 9 held by the work holding mechanism 13 is immersed from above through the opening of the processing tank 32, and the rotary tool 11 is immersed obliquely from above through the gap between the opening and the work. The processing surface 90 of the workpiece outer peripheral surface is polished in the liquid by the tool 11.

  In order to stir the polishing liquid 8 in the processing tank 32, the processing tank 32 is installed on a magnetic stirrer 33, and stirring is performed by a low-speed rotation with a stirrer 34 provided at the bottom in the processing tank 32.

  In addition, since the configuration of the rotary tool 11, the configuration of the polishing liquid 8, the configuration of the organic particles 81 contained therein, and other configurations are the same as those of the above-described representative embodiment, the same reference numerals are given to the same structures. , The description of which is omitted.

  As described above, the embodiments of the present invention have been described, but the present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

  Hereinafter, the results of various tests performed using the polishing solutions of Examples 1 to 9 and Comparative Examples 1 to 4 will be described.

(Polishing liquid)
As shown in the following Table 1, 13 types of polishing liquids of Examples 1 to 9 and Comparative Examples 1 to 4 were prepared.

(Static processing trace test 1)
Using the four types of polishing liquids of Examples 1, 8, 9 and Comparative Example 1, using the local polishing apparatus according to the representative embodiment shown in FIGS. 2 to 4 and FIG. Under the processing conditions (the number of rotations of the rotary tool, the pressing force, and the processing time), a static processing mark test in which scanning of the tool was stopped was performed. The details of the local polishing apparatus are as follows.
・ Rotating body of rotating tool: Fluoro rubber toroidal shape Diameter (d1) 3mm
・ Rotating tool shaft: φ1 mm stainless steel shaft ・ The rotating tool is in the axial direction of the shaft (slightly curved by pressing against the work, but at the position of the tip where the rotating body is provided) ) Is set at 55 degrees with respect to the normal line of the surface to be processed, and the outer diameter (d2) of the polishing action area is 2.2 mm.
・ Motor of rotation support part of rotary tool: Motor whose rotation speed can be controlled in the range of 50 to 4000 rpm

  The work was a synthetic quartz glass substrate, the work surface was a flat surface, and the rotating tool was pressed by lowering the stage by a predetermined amount after the rotating body came into contact with the work surface.

  As can be seen from the measurement results by the scanning white interferometer of FIGS. 8A to 8C and FIG. 9, in each of the examples in which the liquid of the polishing processing liquid was pure water / fluorinate and the organic abrasive grains were acrylic / urethane (FIG. 8A, 8B, and 8C), the polishing is locally performed as in the case of the polishing liquid of Comparative Example 1 using general abrasive grains (FIG. 9). In addition to water, which is a general polishing liquid, it was confirmed that an inert perfluoro compound (fluorinate) was also effective.

(Static processing trace test 2)
Using the two types of polishing liquids of Example 1 and Comparative Example 1, using the same local polishing apparatus and the same type of work (synthetic quartz glass substrate, work surface being flat) as in the static processing mark test 1, Under the processing conditions (rotational speed of the rotary tool, pressing force) shown in Table 3 below, a test was performed to confirm the change in the processing amount of the static processing trace due to the processing time.

  From the graphs of FIGS. 10A and 10B, it can be seen that the processing amount is proportional to the processing time in both Example 1 and Comparative Example 1. It was confirmed that the processing amount of the static processing trace required for the modified polishing was proportional to time.

(Raster scan processing test 1)
Using the five types of polishing liquids of Examples 1, 2, 8 and Comparative Examples 1 and 2, the same local polishing apparatus and the same type of work (synthetic quartz glass substrate, work surface Under the processing conditions (the number of rotations of the rotary tool, the pressing force, and the processing time) shown in Table 4 below, the area of 2.5 mm square is raster-scanned in 10 μm steps as shown in FIG. As a result, in each of the examples and the comparative examples, the same raster scan removal processing as that in FIG. 12 (Comparative Example 1) was confirmed. In each example, the surface roughness was evaluated using an RMS value of 0.187 mm × 0.14 mm by a scanning white interferometer.

  In the case of Comparative Example 1 (silica particles) and Comparative Example 2 (acrylic particles having an average particle diameter smaller than 5 μm), as can be seen by comparing FIGS. 15A and 15B with FIG. The roughness has deteriorated considerably. On the other hand, in the case of Examples 1, 2, and 8 (acrylic particles / urethane particles having an average particle diameter of 10 μm or more), FIG. 14A, FIG. 14B, and FIG. Even after processing, relatively good surface roughness is maintained.

(Static processing trace test 3)
Using the polishing liquid of Example 1 and the same local polishing apparatus as in the above-mentioned static processing mark test 1, pressing force was applied to two types of works (both synthetic quartz glass substrates and silicon substrates have flat work surfaces). FIGS. 16A and 16B show the results of the modified processing.

  As can be seen from the graphs of FIGS. 16A and 16B, the processing amount is proportional to the pressing force.

(Raster scan processing test 2)
Using the polishing liquid of Example 1 and the same local polishing apparatus as in the above-mentioned static processing mark test 1, the rotation speed of the rotary tool was 2,000 rpm and the pressing force of the rotary tool was 0 against the work (the silicon substrate work surface was flat). Under the processing conditions of 0.006 N and processing time of 29 minutes, a raster scan process was performed on a 1.0 mm square area in steps of 10 μm. FIG. 17 shows the measurement results obtained by the scanning white light interferometer.

  The results in FIG. 17 demonstrate that processing can be performed on a silicon substrate as well as processing on a glass substrate (FIG. 12).

(Static processing trace test 4)
A total of 5 types of polishing liquids of Examples 3 to 5, Comparative Example 3, and Comparative Example 4 containing only pure water containing no abrasive grains, and the same local polishing apparatus as in the above-mentioned static processing mark test 1 , A workpiece (synthetic quartz glass substrate, surface to be processed) was processed under the same processing conditions (rotational speed of rotary tool: 1600 rpm, pressing force of rotary tool: 0.012 N, processing time: 1 minute). The results are shown in FIG.

  As shown in the graph of FIG. 18, the polishing amount increased up to the particle size of 15 μm, but the processing amount decreased at the particle size of 30 μm.

(Static processing trace test 5)
Using the four types of polishing liquids of Examples 3, 6, 7 and Comparative Example 4 differing only in the abrasive grain concentration, and the same local polishing apparatus as in the above-mentioned static processing mark test 1, the work (synthetic quartz glass substrate, surface to be processed) FIG. 19 shows the result of processing the same processing condition (plane) under the same processing conditions (the number of rotations of the rotary tool is 1600 rpm, the pressing force of the rotary tool is 0.012 N, and the processing time is 1 minute).

  As shown in the graph of FIG. 19, as the abrasive grain concentration increases, the processing amount also increases. It was found that as the concentration was further increased, the amount of processing increased gradually.

(Modified polishing test 1)
By using the polishing liquid of Example 1 and the same local polishing apparatus as in the above-mentioned static processing mark test 1, it is possible to correct and polish a shape error of a 0.1 mm cycle with respect to a work (a synthetic quartz glass substrate, a surface to be processed is flat). Was tested.
An arbitrary target shape having a width of 0.1 mm is created, and the dwell time distribution is calculated by performing a deconvolution calculation with a unit machining shape calculated based on the static machining trace obtained from the static machining trace test 1 of Example 1. Calculated. Scanning along the residence time distribution was performed on a synthetic quartz glass flat substrate, and measured by a scanning white light interferometer. As a result, a shape very close to the ideal was produced (FIGS. 20 and 21).
Further, as shown in FIG. 22, the surface roughness region hardly changes, and the state before processing is maintained. The surface roughness evaluation is an RMS value of 0.187 mm × 0.14 mm.

(Modified polishing test 2)
Using the polishing liquid of Example 1 and the local polishing apparatus for cylindrical or cylindrical processing according to the embodiment shown in FIGS. 5 and 6 described above, a work (a cylindrical lens made of synthetic quartz glass having a diameter of 10 mm) Was tested to see if it was possible to correct and correct a shape error of 0.15 mm period on the outer peripheral surface).
Similarly to the above-mentioned modified polishing test 1, an arbitrary target shape having a width of 0.15 mm is created, and similarly, the residence time distribution is calculated by deconvolution calculation with the unit processed shape obtained from the static processing trace test 1 of Example 1 above. Calculated. Scanning processing was performed on the surface to be processed along the residence time distribution, and measurement was performed using a scanning white light interferometer. As a result, a shape very close to the ideal was produced (FIG. 23). Further, as shown in FIG. 24, a result was obtained in which the surface roughness region was hardly changed. The surface roughness evaluation is an RMS value of 0.187 mm × 0.14 mm.

  In each of the modified polishing tests, it was possible to obtain a spatial resolution of an ideal target shape and to maintain a surface roughness region. From the above results, the intended correction polishing of the 0.1 mm periodic shape was achieved. This method, which combines a rotating tool and relatively large organic particles, can be said to be a modified polishing method having a high modified spatial resolution and high stability. It is considered to be a technique that is sufficiently useful especially in the development of highly accurate optical elements.

s1 gap d1 diameter d2 outer diameter 1 local polishing apparatus 8 polishing liquid 9 work 11 rotating tool 12 processing liquid supply means 13 work holding mechanism 14 processing liquid ejecting unit 20 rotator 20a outer peripheral surface 201 polishing action area 21 shaft body 22 rotation Supporting part 23 Supporting stand 30 Jet nozzle 31 Recovery tank 32 Processing tank 33 Magnetic stirrer 34 Stirrer 35 Pump 41 X-axis stage 42 Y-axis stage 43 Z-axis stage 81 Abrasive 90 Work surface

Claims (13)

  While supplying a polishing liquid in which abrasive grains composed of organic particles having an average particle diameter of 5 μm or more are dispersed in a liquid, between the rotary tool for work polishing that is locally pressed against the work and the work, A local polishing method in which pressing polishing is performed.   The local polishing method according to claim 1, wherein the rotating tool is made of an elastic material.   The local polishing method according to claim 1, wherein the liquid is pure water or a liquid containing water as a main component. The rotation tool,
A rotating body,
The rotating body is provided at the tip, an axially long shaft body for rotating the rotating body,
A rotation support portion configured to rotate around the shaft while supporting the shaft at the base end side,
The shaft is curved by pressing the outer peripheral surface of the rotating body against the work, and the rotating body is pressed against the work by the elastic restoring force of the curved shaft,
The local polishing method according to claim 1.   The local polishing method according to any one of claims 1 to 4, wherein an outer diameter of a polishing action area on an outer peripheral surface of the rotary tool facing the work is set to 5.0 mm or less.   The local polishing method according to claim 1, wherein the organic particles are acrylic particles or urethane particles. A rotary tool for polishing the workpiece that is pressed locally against the workpiece,
A machining fluid supply unit for supplying a polishing fluid in which abrasive grains made of organic particles having an average particle diameter of 5 μm or more are dispersed in the liquid, between the rotary tool and the work;
Local polishing machine.   The local polishing apparatus according to claim 7, wherein the rotating tool is made of an elastic material.   9. The local polishing apparatus according to claim 7, wherein the liquid is pure water or a liquid containing water as a main component. The rotating tool is
A rotating body,
The rotating body is provided at the tip, an axially long shaft body for rotating the rotating body,
A rotation support portion configured to rotate around the shaft while supporting the shaft at the base end side,
The shaft is curved by pressing the outer peripheral surface of the rotating body against the work, and the rotating body is pressed against the work by the elastic restoring force of the curved shaft,
The local polishing apparatus according to claim 7.   The local polishing apparatus according to any one of claims 7 to 10, wherein an outer diameter of a polishing action area on an outer peripheral surface of the rotating tool facing the work is 5.0 mm or less.   The local polishing apparatus according to any one of claims 7 to 11, wherein the organic particles are acrylic particles or urethane particles. A modified polishing apparatus using the local polishing apparatus according to any one of claims 7 to 12.