JP2016114651A - Method of manufacturing optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical element, which allows insides of a plurality of grooves provided on a resin substrate to be easily subjected to surface planarization using a treatment liquid.SOLUTION: A method of manufacturing an optical element comprises a step of grooving a front surface 31A of a resin substrate with the front surface and a rear surface 31B to form, on the resin substrate, a plurality of grooves 34 which are arranged in parallel to extend from the front surface 31A toward the rear surface 31B and reach one end surface to the other end surface of the resin substrate, a step of covering the side of the front surface 31A of the resin substrate to open only one end surfaces 31C and the other end surfaces of the plurality of grooves 34, and a step of subjecting surfaces in the grooves 34 to surface planarization by pouring a treatment liquid W1 into the plurality of grooves 34 from openings to dissolve the surfaces in the grooves 34 with the treatment liquid W1.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for manufacturing an optical element including a resin substrate on which a plurality of grooves are formed, which is used for an aerial video device.

  As disclosed in Patent Documents 1 and 2 below, in an optical element such as a micromirror array used in an aerial image device, a large number of linear grooves are formed on a resin substrate by dicing.

  The following Patent Documents 3 to 6 disclose a method in which the inside of a groove provided in a resin substrate is surface-treated using a treatment liquid (solvent) coating, a treatment liquid (solvent) vapor, or the like.

  Patent Document 7 below discloses a method of polishing the inside of a groove provided in a quartz glass substrate using a brush.

JP 2014-032394 A JP 2013-254145 A JP 2001-329084 A Japanese Patent Laid-Open No. 06-128398 JP-A-10-239538 Japanese Patent No. 4822357 JP 2000-127021 A

  In an aerial image device, it is necessary to create a clear image using an optical element such as a micromirror array. In that case, a predetermined surface roughness (surface flattening treatment) is required for the inner surface (reflection surface) of the groove formed in the optical element. In the dicing process (cutting process) disclosed in Patent Documents 1 and 2, a predetermined surface roughness (for example, a mirror surface) cannot be obtained on the surface inside the groove.

  In the method of processing the inside of the groove of the resin substrate disclosed in Patent Documents 3 to 6 using a treatment liquid (solvent), vapor of the treatment liquid (solvent), etc. ) Tends to be non-uniform compared to other regions, and the entire surface in the groove cannot be treated uniformly.

  In the case where the method for polishing the inside of the groove applied to the glass substrate using a brush disclosed in Patent Document 7 is applied to the resin substrate, the edge of the groove is not soft because the resin substrate is softer than glass. The problem which will be grind | polished is considered.

  The object of the present invention has been made in view of the above problems, and the surface flattening treatment can be easily performed on the inside of the plurality of grooves provided in the resin substrate using a treatment liquid (solvent). Another object of the present invention is to provide a method for manufacturing an optical element.

  In this method of manufacturing an optical element, a groove is formed on the surface of a resin substrate having a front surface and a back surface, thereby extending from the front surface toward the back surface and reaching the other end surface from one end surface of the resin substrate. Forming a plurality of parallel grooves on the resin substrate, covering the surface side of the resin substrate, and opening only the one end surface and the other end surface of the plurality of grooves; And a step of performing a surface flattening process on the surface in the groove by pouring a treatment liquid into the plurality of grooves from the opening and dissolving the surface in the groove with the treatment liquid.

  In another embodiment, the plurality of grooves formed in the resin substrate include grooves formed in two directions orthogonal to each other.

  In another embodiment, the surface side of the resin substrate is covered with a planar member, so that only the one end surface and the other end surface of the plurality of grooves are opened.

  In another embodiment, two sheets of the resin substrate having the same plurality of grooves are prepared, and the groove of one of the resin substrates is aligned with the groove of the other resin substrate. By bringing the surfaces of the resin substrates into close contact with each other, only the one end surface and the other end surface of the plurality of grooves are opened.

  In another embodiment, the step of performing the surface flattening process includes a step of pressurizing the treatment liquid and introducing it into the groove, and / or aspiration of the treatment liquid from the side opposite to the introduction side of the treatment liquid. The process of carrying out.

  In another aspect, the step of performing the surface flattening treatment includes the step of pouring the treatment liquid into the plurality of grooves from the openings and then pouring the liquid for washing away the solvent into the grooves; and And a step of drying the inside of the groove after pouring.

  In another embodiment, the resin substrate has transparency with a transmittance of 80% or more, and the optical element is a micromirror array used in an aerial image optical device.

  According to this method of manufacturing an optical element, there is provided a method of manufacturing an optical element capable of easily performing a surface flattening process on the inside of a plurality of grooves provided on a resin substrate using a processing liquid (solvent). Can be provided.

1 is a perspective view showing a micromirror array provided with an optical element according to Embodiment 1. FIG. FIG. 3 is a perspective view showing a disassembled state of the micro mirror array provided with the optical element in the first embodiment. It is arrow sectional drawing along the III-III line in FIG. FIG. 3 is a flowchart showing a surface flattening process in the first embodiment. It is a perspective view which shows the state which has arrange | positioned the planar member in the surface of the resin substrate in which the groove | channel was formed in Embodiment 1. FIG. FIG. 5 is a schematic diagram showing a state where the inner surface of the groove formed in the resin substrate is subjected to a surface flattening process using a processing liquid in the first embodiment. FIG. 3 is a schematic diagram of a flow showing a surface flattening process in the first embodiment. It is a schematic diagram which shows the state which has performed the surface planarization process with the process liquid in the internal surface of the groove | channel formed in the resin substrate at the time of using the protection plate of the other form in Embodiment 1. FIG. FIG. 10 is a first schematic diagram illustrating a resin substrate superposition method used in the surface planarization method according to the second embodiment. FIG. 10 is a second schematic diagram showing a method for overlaying resin substrates used in the surface planarization method according to Embodiment 2. 6 is a schematic diagram showing a configuration of a suction device used in a surface flattening method according to Embodiment 2. FIG. 6 is an enlarged perspective view showing a state of a resin substrate held by a suction device used in the surface flattening method according to Embodiment 2. FIG. FIG. 10 is a perspective view of a resin substrate in a third embodiment. 10 is an enlarged perspective view showing a state of a resin substrate held by a suction device in Embodiment 3. FIG. It is a figure which shows the evaluation result in Example 1. FIG.

  Each embodiment will be described below 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. Each of the following embodiments will be described based on a micromirror array provided with an optical element, but the technical idea as an optical element disclosed below can be applied to other than the micromirror array. It is. For convenience of explanation, the depth, width, and number of grooves are not the same as the original size ratio with respect to the size and thickness of the resin substrate, and the size of the groove is made larger than the ratio of the actual dimensions. It is shown. It is planned from the beginning to use a combination of the configurations in each embodiment as appropriate.

[Embodiment 1]
(Optical element)
With reference to FIGS. 1-3, the optical elements 10 and 20 in Embodiment 1 are demonstrated. 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 is used in an aerial image optical device and functions 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 of the present embodiment have substantially the same configuration. The optical elements 10 and 20 include a resin substrate 31. The resin substrate 31 is preferably formed of a member having high transparency (for example, a transmittance of 80% or more).

  The resin substrate 31 has a front surface 31A and a back surface 31B. The resin substrate 31 has a flat shape, and the material thereof is, for example, acrylic or polycarbonate. On the front surface 31A of the resin substrate 31, a plurality of grooves 34 extending from the front surface 31A toward the back surface 31B are formed at predetermined intervals by groove processing (dicing processing) using a dicer (not shown). In the present embodiment, the plurality of grooves 34 have a length that reaches the other end surface 31 </ b> D from one end surface 31 </ b> C of the resin substrate 31, and extend in parallel to each other. The width dimension of the groove 34 is about 0.05 mm to about 2 mm.

  The two optical elements 10 and 20 are arranged such that the extending directions of the plurality of grooves 34 provided on each resin substrate 31 are orthogonal to each other in plan view. In the present embodiment, 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. 4-7, the manufacturing method of the optical elements 10 and 20 is demonstrated. Since the optical element 20 can be formed 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. 4 is a flowchart showing the surface flattening process, FIG. 5 is a perspective view showing a state in which a planar member is arranged on the surface of the resin substrate 31 in which the grooves 34 are formed, and FIG. 6 is formed on the resin substrate 31. FIG. 7 is a schematic diagram showing a state in which the inner surface of the groove 34 is subjected to a surface flattening process using a processing liquid (solvent), and FIG. 7 is a schematic flow diagram showing the surface flattening process. 5 and 6, the film F1 shows a state in which the resin substrate 31 is seen through in order to easily show the internal state.

  With reference to FIG. 5, first, a resin substrate 31 (base plate) is prepared. The material of the resin substrate 31 is acrylic or polycarbonate, for example. On the surface of the resin substrate 31, a plurality of grooves 34 extending from the front surface 31A toward the back surface 31B are formed.

  Next, the surface 31A side of the resin substrate 31 is covered with a film F1 as a planar member. The film F1 is attached to the surface 31A of the resin substrate 31 using a double-sided tape or the like. Thereby, only one end surface and the other end surface of the plurality of grooves 34 are opened.

  Next, as shown in FIG. 6, the protective plate 50 is placed on the end face so as not to block the opening on the one end face side of the groove 34. The protective plate 50 may be any material as long as it is resistant to the processing liquid.

  A solvent W1 such as acetone, ethylene dichloride, methyl alcohol, tetrahydrofuran or the like is introduced into the groove 34 as a treatment liquid for finishing the inside of the groove 34 in a mirror state. Thus, the surface of the inside of the groove 34 is subjected to a surface flattening process by dissolving the inside of the groove while the solvent W1 falls inside the groove 34 by its own weight.

  Next, as shown in FIG. 7, after the surface flattening process inside the groove 34 using a solvent, pure water is poured into the groove 34 as a liquid for washing away the solvent W1 (S20). Furthermore, after pouring pure water into the inside of the groove 34, the inside of the groove 34 is dried using air blow (S30).

  By passing through the above steps, it is possible to perform the surface treatment only on the inside over the entire length of the groove 34 while protecting the resin substrate 31 that is not desired to be treated and protecting the edge. In addition, a narrow groove (for example, a groove width that is difficult to perform physical processing such as polishing at about 0.05 mm to 2 mm) and a large number of grooves can be processed at once, thereby reducing the number of steps. it can.

  As a result, the smoothness of the side surface of the groove 34, which cannot be obtained only by machining, can be obtained by a simple method, and improvement in the display performance of the device can be expected. In addition, if the closed space is not formed inside the groove, the processing liquid may overflow to the surface side if the processing liquid does not efficiently enter the groove, and the processing liquid may adhere to a portion that is not desired to be processed. However, in this embodiment, such a problem does not occur.

  A protective plate 50A as shown in FIG. 8 may be used to further protect the end face of the resin substrate 31 with the treatment liquid. The protective plate 50A is provided with an extending portion 50A1 that extends to a region where the groove 34 is not formed. By using this protective plate 50A, the end surface of the resin substrate 31 can be protected from the processing liquid by the protective plate 50A.

[Embodiment 2]
Next, with reference to FIGS. 9 to 12, a surface flattening processing method in the second embodiment will be described. FIGS. 9 and 10 are first and second schematic views showing a method for overlaying resin substrates used in the surface flattening method according to the second embodiment, and FIG. 11 is a schematic view showing the configuration of the suction device. 12 is an enlarged perspective view showing a state of the resin substrate held by the suction device.

  Referring to FIG. 9, in the present embodiment, two resin substrates 31 each having the same plurality of grooves 34 are prepared, and groove 34 of one resin substrate 31 and groove 34 of the other resin substrate 31 are prepared. Are brought into close contact with each other so that only one end face and the other end face of the plurality of grooves 34 are opened.

  Referring to FIG. 10, for adhesion between two resin substrates 31, a weak adhesive film (not shown) having a size covering the entire surface 31 </ b> A is sandwiched between two resin substrates 31 and a clamp 41 is used. ing. As a result, the grooves 34 of the two resin substrates 31 face each other, and only one end face and the other end face of the groove 34 are opened.

  Next, referring to FIG. 11, the two resin substrates 31 fixed by the clamp 41 are held in the suction device 1000. The suction device 1000 includes a mounting table with a suction port 121 that holds two resin substrates 31, a primary suction pipe 120 having an opening / closing valve 125, a negative pressure chamber 130 to which the primary suction pipe 120 is connected, a negative pressure chamber 130, a secondary suction line 150 having an open / close valve 135 and a solvent trap 140, and an oilless vacuum pump 160 connected to the secondary suction line 150.

  Referring to FIGS. 11 and 12, two resin substrates 31 are placed on mounting table 121 with a suction port, and processing liquid is introduced from one end face of two resin substrates 31, and processing liquid is introduced from the other end face. Is sucked using a suction device 1000. Thereafter, by introducing pure water from one end face of the two resin substrates 31, the inside of the groove can be cleaned.

  Thereby, the processing liquid can pass through the groove 34 uniformly. Further, since the processing liquid is sucked using the suction device 1000, it is preferable when the processing is to be completed in a short time or when the length of the groove is long.

  In the above-described embodiment, the case where the processing liquid is sucked from the side opposite to the processing liquid introduction side has been described. However, a processing step in which the processing liquid is pressurized and introduced into the groove 34 may be employed.

[Embodiment 3]
Next, with reference to FIG. 13 and FIG. 14, the surface flattening process in the groove | channel 34 of the resin substrate 31X which has another form is demonstrated. FIG. 13 is a perspective view of the resin substrate 31 in the present embodiment, and FIG. 14 is an enlarged perspective view showing a state of the resin substrate 31X held by the suction device.

  In the resin substrate 31 used in each of the above-described embodiments, the plurality of grooves 34 extend linearly so as to have a parallel relationship with each other. However, the plurality of resin substrates 31X of the present embodiment have a plurality of grooves. The grooves 34 are provided in a lattice shape so as to be orthogonal to each other.

  Referring to FIG. 14, in the case where the surface flattening process is performed on the groove 34 having such a shape, the above-described suction device 1000 has a configuration capable of sucking the processing liquid from the two side surfaces of the resin substrate 31. By using the mounting table with suction port 121 </ b> A and the primary suction pipe 120 </ b> D, the surface 34 can be easily subjected to surface flattening.

  In addition, you may employ | adopt the processing method which covers a groove | channel with the film F1 as a planar member demonstrated using FIGS. 6-8 with respect to the resin substrate 31X.

Example 1
Next, a method for manufacturing an optical element employing the surface flattening process in the first embodiment will be described. As the resin substrate 31, a groove 34 was processed on an acrylic plate having a thickness of 3 mm using a dicing machine (DAD522 manufactured by DISCO Corporation). The number of grooves 34 was 100, the groove width was 0.3 mm, the processing depth was 0.9 mm, and the groove pitch was 1.0 mm. As conditions for the dicing machine, the following conditions 1, 2 and 3 were implemented.

  (Condition 1) Diamond blade # 5000, φ52 × thickness 0.3 mm, blade rotation speed 30000 rpm, feed rate 0.5 mm / s.

  (Condition 2) Diamond blade # 2000, φ52 × thickness 0.3 mm, blade rotation speed 30000 rpm, feed rate 0.5 mm / s.

  (Condition 3) Diamond blade # 2000, φ52 × thickness 0.3 mm, blade rotation speed 30000 rpm, feed rate 1.0 mm / s.

  A dicing tape (River Alpha manufactured by Nitto Denko) was attached to the surface where the groove 34 was processed to form a closed space in the groove 34 while protecting the surface.

  On one end surface of the plurality of grooves 34 of the resin substrate 31, a metal protective plate 50 was pasted with a double-sided tape within a range not to hide the grooves (see FIG. 6).

  The resin substrate 31 was erected and held so that the protective plate 50 was on the upper side, and acetone as the treatment liquid W1 was dropped from one end face groove of the upper groove 34 and injected into the groove 34.

  After 20 s to 40 s, pure water was injected in the same manner to clean the inside of the groove 34, and then the inside of the groove 34 was dried by air blow. Thus, the manufacture of the resin substrate 31 having a plurality of grooves was completed.

(Evaluation)
A cut was made at the center of the groove 34 from the back side of the resin substrate 31 and divided into two, and the surface roughness (Ra) of the groove side surface was measured by non-contact optical measurement (wyko NT9100). The results are shown in FIG.

  In condition 1, the surface roughness (Ra) before the surface flattening treatment was 95.2 nm, but after the treatment, it was improved to 47.8 nm, and it was confirmed that it was used as a good mirror surface on the side surface of the groove 34. did it. Further, it was confirmed that the resin substrate 31 can be used as a micromirror array used in an aerial image optical device without deformation or white turbidity of the edges of the one end surface and the other end surface of the groove 34.

  In condition 2, the surface roughness (Ra) before the surface flattening treatment was 253.1 nm, but after the treatment, it was improved to 108.3 nm, and it was confirmed that it was used as a mirror surface on the side surface of the groove 34. . Further, it was confirmed that the resin substrate 31 can be used as a micromirror array used in an aerial image optical device without deformation or white turbidity of the edges of the one end surface and the other end surface of the groove 34.

  In condition 3, the surface roughness (Ra) before the surface flattening treatment was 349.4 nm, but after the treatment, it was improved to 151.6 nm, and it was confirmed that it was used as a mirror surface on the side surface of the groove 34. . Further, it was confirmed that the resin substrate 31 can be used as a micromirror array used in an aerial image optical device without deformation or white turbidity of the edges of the one end surface and the other end surface of the groove 34.

(Example 2)
Next, a method for manufacturing an optical element employing the surface flattening process in the second embodiment will be described. As the two resin substrates 31, the grooves 34 were processed using a dicing machine (DAD522 manufactured by DISCO Corporation) on an acrylic plate having a thickness of 3 mm. The number of grooves 34 was 100, the groove width was 0.3 mm, the processing depth was 0.9 mm, and the groove pitch was 1.0 mm. The conditions of the dicing machine were diamond blade # 5000, φ52 × thickness 0.3 mm, blade rotation speed 30000 rpm, and feed rate 1.0 mm / s.

  As shown in FIG. 10, the entire surface 31A is covered from both back sides with the surfaces on the groove processing side in close contact so that the positions of the grooves 34 of the two resin substrates 31 coincide and become parallel. It fixed with the clamp 41 on both sides of the weak adhesive film.

  As shown in FIG. 11 and FIG. 12, the negative end adjusted to −0.02 to −0.04 MPa while the one end of the groove 34 is brought into close contact with the mounting table with suction port 121 and suctioned with the oilless vacuum pump 160. Connected to the pressure chamber 130, a reservoir receiving portion is provided at the groove end on the opposite side, and injected into the groove 34 in the order of acetone and pure water as treated water. By continuing the suction, the inside of the groove 34 is also dried.

(Evaluation)
Although the surface roughness (Ra) before the surface flattening treatment was 118.7 nm, it was improved to 70.7 nm after the treatment, and it was confirmed that it was used as a good mirror surface on the side surface of the groove 34. Further, it was confirmed that the resin substrate 31 can be used as a micromirror array used in an aerial image optical device without deformation or white turbidity of the edges of the one end surface and the other end surface of the groove 34.

  Although the embodiments and examples have been described above, the above disclosure is illustrative in all respects and 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 31, 31X Resin substrate, 31A Front surface, 31B Back surface, 31C One end surface, 31D Other end surface, 34 Groove, 41 Clamp, 50, 50A Protection plate, 50A1 Extension, 100 Micromirror array, 120, 120D Primary suction line, 121 Mounting table with suction port, 121A Mounting table with suction port, 125, 135 Open / close valve, 130 Negative pressure chamber, 140 Solvent trap, 150 Secondary suction line, 160 Oilless vacuum pump, 1000 suction Equipment, F1 film, W1 solvent (treatment liquid).

Claims (7)

A plurality of parallel grooves extending from the front surface to the back surface and reaching the other end surface of the resin substrate by performing groove processing on the front surface of the resin substrate having a front surface and a back surface Forming the resin substrate on the resin substrate;
Opening only the one end face and the other end face of the plurality of grooves by covering the surface side of the resin substrate; and
Pouring a treatment liquid into the plurality of grooves from the opening, and performing a surface flattening process on the surface in the groove by dissolving the surface in the groove with the treatment liquid;
A method for manufacturing an optical element.   The optical element manufacturing method according to claim 1, wherein the plurality of grooves formed in the resin substrate include grooves formed in two directions orthogonal to each other.   The method for manufacturing an optical element according to claim 1, wherein only the one end surface and the other end surface of the plurality of grooves are opened by covering the surface side of the resin substrate with a planar member.   Two resin substrates on which the same plurality of grooves are formed are prepared, and the grooves of one of the resin substrates are aligned with the grooves of the other resin substrate. The method for manufacturing an optical element according to claim 1, wherein only the one end face and the other end face of the plurality of grooves are opened by bringing the surfaces into close contact with each other. The step of performing the surface flattening treatment includes
5. The method according to claim 1, further comprising a step of pressurizing and introducing the treatment liquid into the groove and / or a step of sucking the treatment liquid from a side opposite to the introduction side of the treatment liquid. The manufacturing method of the optical element of description. The step of performing the surface flattening treatment includes
After pouring the treatment liquid into the plurality of grooves from the opening, and then pouring the liquid to wash away the solvent into the grooves;
Drying the inside of the groove after pouring the liquid;
The manufacturing method of the optical element of any one of Claims 1-5 containing these. The resin substrate has a transparency of 80% or more,
The said optical element is a manufacturing method of the optical element of any one of Claims 1-6 which is a micromirror array used for an aerial image optical device.