JP2016118665A - Method for manufacturing optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical element capable of performing appropriate mirror polishing corresponding to the shape of a groove.SOLUTION: A method for manufacturing an optical element comprises the steps of: preparing a plate material 10N in which a groove 34 is formed on a surface 31A; making a polishing tool 65 from a transferred material by transferring the shape of a base material for templating having the shape of the groove 34 of the plate material 10N or the shape corresponding to the groove 34 of the plate material 10N; supplying a polishing agent 66 between the polishing tool 65 and the plate material 10N; and polishing the groove 34 by relatively moving the polishing tool 65 and the plate material 10N in a state in which the polishing tool 65 is in contact with the plate material 10N.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a method for manufacturing an optical element including a step of polishing a groove.

  As disclosed in Patent Documents 1 to 3 below, when an optical element such as a micromirror array is manufactured, a plurality of grooves are formed on the surface of a plate material (for example, a resin substrate). The plurality of grooves can be formed by, for example, machining or molding, but it is difficult to finish the inner wall surface of the groove to a mirror surface state only by machining or molding.

  For example, when a groove portion is formed by dicing, a tool mark (processing trace by a dicer) remains on the inner wall surface of the groove portion. Considering the quality and performance as an optical element (for example, reflected light rate), the inner wall surface of the groove is required to be finished in a sufficient mirror surface state by performing a polishing process.

  Japanese Unexamined Patent Publication No. 2000-127021 (Patent Document 4) describes that a groove portion is formed in a quartz glass rod by groove processing using a diamond blade, and the groove portion is mirror-polished with a polishing brush.

JP 2014-032394 A JP 2013-254145 A JP 2013-210610 A JP 2000-127021 A

  When the method disclosed in Japanese Patent Application Laid-Open No. 2000-127021 (Patent Document 4) is adopted, that is, when mirror polishing is performed using a polishing brush, the shape of the polishing brush may be the groove portion depending on the shape of the polishing brush. The contact efficiency between the polishing brush and the groove portion is lowered due to the fact that the shape does not correspond sufficiently, and the groove portion may not be properly polished (for example, uniformly).

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing an optical element capable of performing appropriate mirror polishing corresponding to the shape of a groove. .

  An optical element manufacturing method according to the present invention includes a step of preparing a plate member having a groove portion formed on a surface thereof, a shape forming mother having a shape of the groove portion of the plate member, or a shape corresponding to the groove portion of the plate member. By transferring the shape of the material, a step of producing a polishing tool from the material to be transferred, a step of supplying an abrasive between the polishing tool and the plate material, and the polishing tool and the plate material were brought into contact with each other. And polishing the groove by moving these relative to each other in a state.

Preferably, the abrasive includes cerium oxide, colloidal silica, or alumina.
Preferably, the plate material is formed of a resin member.

Preferably, the transfer material is made of silicone.
Preferably, the polishing tool formed of the silicone has a durometer A hardness of 12 or more and 88 or less.

  Preferably, a clearance of 5 μm or more and 20 μm or less is provided between the polishing tool and the inner wall surface of the groove when the polishing tool is in contact with the plate at the start of polishing the groove. Yes.

  The polishing tool used in the above manufacturing method is manufactured by transfer from a plate material itself to be polished or from a material having the same shape. Since such a polishing tool has a shape that accurately corresponds to the shape of the plate material to be polished as compared with the case of using a polishing brush, it has high contact efficiency by using such a polishing tool. Thus, it is possible to perform appropriate mirror polishing corresponding to the shape of the groove.

It is a perspective view which shows the micromirror array provided with the optical element obtained by the manufacturing method of the optical element in embodiment. It is a perspective view which shows the state which decomposed | disassembled the micromirror array provided with the optical element obtained by the manufacturing method of the optical element in embodiment. It is arrow sectional drawing along the III-III line in FIG. It is sectional drawing which shows the 1st process of the manufacturing method of the optical element in embodiment. It is sectional drawing which shows the 2nd process (dicing process process) of the manufacturing method of the optical element in embodiment. It is sectional drawing which shows the 3rd process (process which produces a polishing tool) of the manufacturing method of the optical element in embodiment. It is sectional drawing which shows the 4th process (process which produces a polishing tool) of the manufacturing method of the optical element in embodiment. It is sectional drawing which shows the 4th process (process which produces a polishing tool) of the manufacturing method of the optical element in the modification of embodiment. It is sectional drawing which shows the 5th process (process which sets a board | plate material to a polishing tool) of the manufacturing method of the optical element in embodiment. It is sectional drawing which shows the 6th process (mirror polishing process) of the manufacturing method of the optical element in embodiment. It is sectional drawing for demonstrating the mirror polishing process of the manufacturing method of the optical element in the other structure of embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. The following embodiments will be described based on a micromirror array provided with an optical element. However, the optical element disclosed below and the technical idea as a manufacturing method thereof are applicable to other than the micromirror array. It can be done.

(Optical element)
The optical elements 10 and 20 (see FIGS. 1 and 2 etc.) are obtained by carrying out the method for manufacturing an optical element in the embodiment. FIG. 1 is a perspective view showing a micromirror array 100 including optical elements 10 and 20, and FIG. 2 is a perspective view showing an exploded state of the micromirror array 100. 3 is a cross-sectional view taken along the line III-III in FIG.

  As shown in FIG. 1, the micromirror array 100 includes a mirror image of a projection object arranged on one surface side of the micromirror array 100 on the other surface side that is plane-symmetric with respect to the micromirror array 100. An image can be formed at a spatial position. That is, the micromirror array 100 can function as an imaging optical element for imaging a three-dimensional or two-dimensional object and an image in a space.

  As shown in FIGS. 1 and 2, the optical elements 10 and 20 constituting the micromirror array 100 have substantially the same configuration. The optical elements 10 and 20 are formed of a plate-like member (plate material) and have a front surface 31A and a back surface 31B. The material of the optical elements 10 and 20 is a resin such as acrylic or polycarbonate. The material of the optical elements 10 and 20 may be glass.

  A plurality of grooves 34 extending at a predetermined depth from the front surface 31A toward the back surface 31B are formed on the front surface 31A of the optical elements 10 and 20. The plurality of groove portions 34 have lengths that reach the end surface 31D from the end surfaces 31C of the optical elements 10 and 20, and extend in parallel with each other. Although details will be described later, the plurality of groove portions 34 are formed by dicing using a dicer 50 (see FIG. 5). The plurality of grooves 34 may be formed by molding (for example, injection molding).

  As shown in FIG. 3, each groove 34 has an inner wall surface 34a, a bottom surface 34b, and an inner wall surface 34c. The inner wall surfaces 34a and 34c have a positional relationship facing each other and are formed to be orthogonal to the surface 31A of the optical element. A corner edge portion 35a is formed between the surface 31A of the optical element and the inner wall surface 34a of the groove portion 34, and a corner edge portion 35b is formed between the surface 31A of the optical element and the inner wall surface 34c of the groove portion 34. Is formed. The corner edge portions 35a and 35b are portions corresponding to the boundary line between the surface 31A of the optical elements 10 and 20 and the groove portion 34 formed on the surface 31A.

  Referring to FIGS. 1 and 2 again, the two optical elements 10 and 20 are arranged such that the extending direction of each groove 34 is orthogonal to each other in plan view. The micromirror array 100 is configured such that the surface 31A of the optical element 10 in which the groove 34 is formed and the surface 31A of the optical element 20 in which the groove 34 is formed contact each other. The optical elements 10 and 20 are bonded to each other by, for example, a photocurable resin.

(Optical element manufacturing method)
With reference to FIGS. 4-10, the manufacturing method of the optical elements 10 and 20 is demonstrated. Since the optical element 20 can be manufactured using the same manufacturing method as the optical element 10, the manufacturing method will be described here with a focus on the optical element 10.

  Referring to FIG. 4, first, a plate material 10M (base plate) having a front surface 31A and a back surface 31B is prepared. The plate member 10M has a rectangular parallelepiped shape and is formed of a resin member such as acrylic or polycarbonate. The material of the plate 10M may be glass. The size of the plate material 10M is, for example, 60 mm × 60 mm × thickness 3.0 mm.

  The plate material 10M is placed on the processing table 40. The processing table 40 is provided with a plurality of suction holes 41. By sucking air through the plurality of suction holes 41, the back surface 31B of the plate material 10M is vacuum-sucked to the surface of the processing table 40, and the plate material 10M is fixed to the surface of the processing table 40.

(Dicing process)
Referring to FIG. 5, dicing is performed on surface 31 </ b> A of plate member 10 </ b> M using dicer 50 (rotary blade). For example, a dicing machine (DAD522) manufactured by DISCO Corporation can be used as the processing machine. As the dicer 50, a diamond blade having # 5000, φ52 × thickness 0.5 mm can be used. The rotation speed of the dicer 50 can be set to 30000 rpm, and the feed speed of the dicer 50 can be set to 1.0 mm / s.

  By dicing, a plurality of (for example, 13) groove portions 34 extending from the front surface 31A toward the back surface 31B are formed on the front surface 31A of the plate member 10M. If the direction orthogonal to the direction in which the groove 34 extends is the width direction, for example, the width of the groove 34 is 0.5 mm and the groove depth is 0.9 mm.

  The groove 34 formed by dicing has an inner wall surface 34a, a bottom surface 34b, and an inner wall surface 34c. The inner wall surfaces 34a and 34c have a positional relationship facing each other and are orthogonal to the surface 31A of the plate member 10M. The width of the groove 34 corresponds to the distance between the inner wall surface 34a and the inner wall surface 34c.

  As shown in FIG. 5, a corner edge portion 35a is formed between the surface 31A of the optical element (resin substrate) and the inner wall surface 34a of the groove 34, and the inside of the surface 31A of the optical element (resin substrate) and the groove 34 is formed. A corner edge portion 35b is formed between the wall surface 34c. By forming the plurality of groove portions 34 in the plate material 10M, a plate material 10N (see FIG. 6), which is a base plate (front body) of the optical element, is obtained. Tool marks (processing marks by the dicer 50) remain on the inner wall surfaces 34a and 34c of the groove 34 of the plate member 10N.

(Process for making polishing tools)
Referring to FIG. 6, after the plate member 10N having the groove 34 formed on the surface 31A is prepared, a plastic container 64 is prepared, and silicone 63 (a material to be transferred) that can be changed from a liquid state to a solid is disposed in the container 64. Pour into the inside. For example, as the silicone 63, a silicone RTV rubber “KE-17” for mold making manufactured by Shin-Etsu Chemical Co., Ltd. can be used. The plate material 10N is attached to the height regulating plate 60 together with the fixture 61.

  Referring to FIG. 7, plate material 10 </ b> N is immersed in silicone 63 from the surface 31 </ b> A side of plate material 10 </ b> N. The silicone 63 is cured (solidified) when a predetermined time elapses. By transferring the shape of the groove 34 of the plate material 10N to the silicone 63, a polishing tool 65 (see FIG. 9) is produced from the silicone 63.

  Referring to FIG. 8, instead of using plate material 10N, mold base material 10S may be used. The mold base material 10S has a shape corresponding to the groove 34 of the plate material 10N. In other words, the mold base material 10S has a plurality of (for example, 17) groove portions having substantially the same shape as the groove portion 34 of the plate material 10N. For example, the mold base material 10S has a size of 80 mm × 80 mm × thickness of 3.0 mm, a groove width of 0.5 mm, and a groove depth of 0.9 mm. Even when the base material for mold making 10S is used, the polishing tool 65 (see FIG. 9) is produced from the silicone 63 (material to be transferred) by transferring the shape of the base material for mold making 10S to the silicone 63. Will be.

  The polishing tool 65 formed of silicone preferably has a durometer A hardness of 12 or more and 88 or less. The polishing tool 65 does not lose its shape during polishing, and it is possible to perform appropriate polishing with little damage to the resin plate material 10N such as acrylic. . Note that the material of the transfer material is not limited to the production of the polishing tool 65 by molding using silicone, and the polishing tool 65 may be produced using a material other than silicone.

  Referring to FIG. 9, after producing polishing tool 65 from a transfer material (silicone 63), polishing tool 65 is disposed at a predetermined position in plastic container 67. Next, an abrasive 66 having an amount exceeding the height of the polishing tool 65 is supplied into the container 67. The abrasive 66 preferably contains cerium oxide, colloidal silica, or alumina. Cerium oxide is suitable when the material of the plate 10N is glass. Colloidal silica or alumina is suitable when the material of the plate 10N is a resin such as acrylic or polycarbonate.

  For example, as the abrasive 66, a polishing material “POLIPLA203H” (“POLIPLA” is a registered trademark) manufactured by Fujimi Incorporated can be used. After supplying the abrasive 66 into the container 67, the plate material 10N is immersed in the abrasive 66, and the groove 34 of the plate material 10N and the corresponding portion of the polishing tool 65 are fitted. In this state, the abrasive 66 is supplied between the polishing tool 65 and the plate material 10N (the abrasive 66 enters between them).

(Mirror polishing process)
Referring to FIG. 10, plate member 10N and polishing tool 65 are brought into contact with each other, and these are relatively moved in a state where a pressing force of 5 kg is applied to plate member 10N.

  As shown in FIG. 11, when the polishing of the groove portion 34 is started, when the plate 10N is in contact with the polishing tool 65, the gap between the polishing tool 65 and the inner wall surfaces 34a and 34c of the groove portion 5 is 5 μm or more. A clearance CL of 20 μm or less may be provided. The clearance CL is set to an optimum value according to the type of polishing agent 66, the polishing rate, and the like. The clearance CL can be easily set to a desired value by changing the amount of shrinkage of the material to be transferred (silicone 63) when the polishing tool 65 is manufactured, the width of the groove portion of the base material for molding 10S, and the like. It is possible to set.

  As the plate material 10N repeatedly moves back and forth in a direction perpendicular to the paper surface of FIG. 10 (FIG. 11), the groove 34 of the plate material 10N is polished. For example, the mirror polishing process is completed after 5 minutes of polishing (sliding). Tool marks (fine scratches) remaining on the inner wall surfaces 34a and 34c of the groove 34 are almost removed by polishing. For example, a mirror surface having a surface roughness (Ra) of 0.1 μm or less can be formed on the inner wall surfaces 34a and 34c.

(Function and effect)
The polishing tool 65 used in the manufacturing method described above is manufactured by transfer from the plate material 10N itself to be polished or from the mold base material 10S having the same shape. Since such a polishing tool 65 has a shape that accurately corresponds to the shape of the plate 10N to be polished as compared with the case where a polishing brush is used, the groove portion 34 can be obtained by using such a polishing tool 65. The corner edge portions 35a and 35b are hardly deformed. In other words, a so-called “sagging” shape change hardly appears in the corner edge portions 35 a and 35 b of the groove 34.

  Japanese Patent Laid-Open No. 2000-127021 (Patent Document 4) describes that the groove portion is polished with a polishing brush. However, when the width of the groove portion 34 is narrow (for example, when the groove width is 0.5 mm or less), When the depth of the groove 34 is deep (for example, when the groove depth is 1.0 mm or less), it is difficult to perform an appropriate polishing process with a polishing brush. It is also expensive to prepare a special polishing brush tailored to the width, depth, pitch, etc. of the groove.

  On the other hand, according to the technique in which the polishing tool 65 is produced by molding from a transfer material such as silicone and the groove portion 34 is polished using the polishing tool 65, the working time can be shortened, and the optical element can be manufactured. The cost related to this can be reduced. According to the technique of mold shaping, it is possible to flexibly cope with the size and shape of the groove 34, and it is also possible to obtain a polishing tool 65 having high shape accuracy. Therefore, according to the method for manufacturing an optical element in the above-described embodiment, high contact can be achieved while appropriately removing impurities (such as fine powder) remaining on the surface of the groove portion 34 without manufacturing an expensive polishing brush or the like. It is possible to perform an appropriate mirror polishing corresponding to the shape of the groove 34 having efficiency. As a result, it is possible to prevent the surface shape of the plate material 10N from changing, for example, the plate material 10N from warping, the concave / convex shape of the groove 34, or the shape of the corner edge portions 35a and 35b from being collapsed. According to the optical elements 10 and 20 manufactured as described above (see FIGS. 1 to 3), it is possible to realize the micromirror array 100 that can form a bright and high-brightness image.

(Experimental example)
After producing the optical element based on the manufacturing method of the above-mentioned embodiment, the optical element was cleaved by cutting from the back surface 31B side of the optical element toward the center of the groove 34. When the surface state of the groove 34 was observed using a microscope (× 100), it was found that the tool mark was almost completely removed.

  Furthermore, when the surface roughness of the inner wall surface of the groove portion 34 was measured with a non-contact optical measuring instrument “Wyko NT9100” manufactured by Veeco, the Rt value before the polishing treatment was 200 nm, but after the polishing treatment The Rt value of was 100 nm. A so-called “sag” shape change did not appear in the corner edge portions 35 a and 35 b of the groove 34. From these results, according to the method of manufacturing an optical element in the above-described embodiment, the shape of the groove 34 having high contact efficiency while appropriately removing impurities (such as fine powder) remaining on the surface of the groove 34. It can be seen that appropriate mirror polishing corresponding to the above can be performed.

  Although the embodiment has been described above, the above disclosure is illustrative in all respects and is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10, 20 optical element, 10M, 10N plate material, 10S mold base material, 31A surface, 31B back surface, 31C, 31D end surface, 34 groove, 34a, 34c inner wall surface, 34b bottom surface, 35a, 35b corner edge portion, 40 processing Table, 41 Suction hole, 50 Dicer, 60 Height restriction plate, 61 Fixing tool, 63 Silicone, 64, 67 Container, 65 Abrasive tool, 66 Abrasive, 100 Micromirror array, CL clearance.

Claims (6)

Preparing a plate having a groove formed on the surface;
Producing a polishing tool from the material to be transferred by transferring the shape of the groove portion of the plate material, or the shape of a mold base material having a shape corresponding to the groove portion of the plate material;
Supplying an abrasive between the polishing tool and the plate material;
Polishing the groove part by relatively moving the polishing tool and the plate in contact with each other.
A method for manufacturing an optical element. The abrasive includes cerium oxide, colloidal silica, or alumina.
The manufacturing method of the optical element of Claim 1. The plate material is formed from a resin member,
The manufacturing method of the optical element of Claim 1 or 2. The transfer material is formed from silicone,
The manufacturing method of the optical element in any one of Claim 1 to 3. The polishing tool formed from the silicone has a durometer A hardness of 12 or more and 88 or less.
The manufacturing method of the optical element of Claim 4. In a state where the polishing tool is in contact with the plate material at the time of starting the polishing of the groove portion, a clearance of 5 μm or more and 20 μm or less is provided between the polishing tool and the inner wall surface of the groove portion.
The manufacturing method of the optical element in any one of Claim 1 to 5.

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