JP2007199540A - Reflection-type replica photonic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection-type replica photonic device that prevents an increase of stray light due to the internal reflection/scattering of the light that penetrates a metallic reflective film, even when the thickness of the metallic reflective film is reduced. <P>SOLUTION: A tar epoxy resin which is made by mixing an epoxy resin, and tar pitch and swelling coal as a light-absorbing material is used for a resin material for transferring and replicating the shape of an original photonic device to a resin layer on a separate substrate by a stamping operation, directly or through a negative master photonic device. Accordingly, the transmitted light is absorbed by the resin material, and will not cause reflection/scattering. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reflective replica optical element used in various optical instruments and measuring instruments.

  Optical elements such as various lenses, mirrors, and diffraction gratings that are widely used in optical instruments such as cameras, microscopes, and telescopes, and measuring instruments such as spectrometers and demultiplexers generally require high processing accuracy. There are many things to do. In particular, the production of optical elements that require the highest degree of precision, such as aspherical optical elements such as parabolic mirrors and ellipsoidal mirrors, and various diffraction gratings, requires extremely sophisticated manufacturing equipment and complicated work processes. Is necessary, and therefore its production cost is very high. For this reason, for mass production of these optical elements, a method of manufacturing replica optical elements from one original optical element (master) by transfer / duplication and supplying the replica optical elements to the market is widely adopted.

  The following is a typical method for producing a large number of replica optical elements from a master optical element produced in advance by an optimum method.

  In the first stage, a negative master optical element is produced by inverting the uneven shape of the original master optical element. First, a release material is applied to the surface of the master optical element, a resin layer having a predetermined thickness is sandwiched between the master optical element and a separately prepared negative master substrate, and the resin layer is left as it is. Leave until fully cured. Thereafter, if the master optical element is separated on the surface of the release material, a negative master optical element is obtained which is engraved on the surface with a shape in which the irregularities on the surface of the master optical element are reversed.

In the second stage, the concavo-convex shape of the negative master optical element is inverted and engraved to produce a replica optical element having the same shape as the master optical element. First, a replica substrate is prepared, and a resin layer having a predetermined thickness is applied to the surface of the replica substrate. A negative master optical element coated with a release material on the surface is pressed onto the resin layer and left as it is until the resin layer is completely cured. Thereafter, the negative master optical element is separated on the surface of the release material. After the release material remaining on the resin layer is washed away, a metal reflective film required for the purpose of use of the optical element is finally applied to the surface of the resin layer to complete a reflective replica optical element. For example, in the case of an aspherical mirror or a replica of a reflective diffraction grating, a metal reflective film such as aluminum is deposited on the surface. (See Patent Document 1)
Japanese Patent Laid-Open No. 7-261010

  However, the replica optical element manufactured by the above method has the following problems.

  One factor that determines the accuracy of the reflective replica optical element is the surface roughness of the metal reflective film. If the surface roughness increases, a part of the reflected light deviates from the correct direction and is scattered in an irregular direction, so that the performance of the optical element is greatly deteriorated. It is also known that the surface roughness increases as the thickness of the metal reflective film deposited by vacuum deposition increases. For this reason, in order to suppress the surface roughness, it is required to reduce the thickness of the metal reflective film deposited on the surface of the reflective replica optical element. However, when the metal reflection film is thinned, a part of the incident light to the optical element passes through the metal reflection film and enters the resin layer and the substrate. Of the intrusion light, a portion reflected / scattered at the boundary surface between the resin and the substrate or the bottom surface of the substrate is again emitted to the outside through the metal reflection film and disturbs the original reflected light of the metal reflection film. The result of causing this disturbance varies depending on the type of the reflective replica optical element. In the reflection type diffraction grating, this disturbance appears as stray light. In the condensing spherical mirror and parabolic mirror used in the imaging optical system, the above disturbance appears as unclear imaging or resolution degradation.

  The present invention solves the above-mentioned problems of the prior art and removes the reflected light from the inside of the reflective replica optical element, thereby reducing the thickness of the metal reflective film as much as possible and reducing the surface roughness. Reflective replica optical element manufactured by transferring and replicating the shape of the original optical element to a resin layer on a separate substrate directly or via a marking operation via a negative master optical element And the said resin layer is a thing containing the substance which absorbs light, It is characterized by the above-mentioned.

  By depositing a thin metal reflective film, it is possible to manufacture a reflective replica optical element having a small surface roughness. Even if a part of the incident light passes through the metal reflection film, the transmitted light is absorbed by the resin, so there is no light that is reflected / scattered in the resin layer or the substrate and re-emitted. For this reason, it is possible to manufacture a reflective diffraction grating with little stray light, a spherical mirror or a parabolic mirror exhibiting high-precision imaging.

  The object of the present invention is to remove the light transmitted through the metal reflective film before re-reflecting, which is a substance that absorbs light into the resin on which the surface shape of the negative master optical element is imprinted. It is realized by mixing. A process of manufacturing a replica of a reflective concave diffraction grating as one embodiment of the present invention will be described below with reference to FIG.

  First, the negative master 1 manufactured by the method described in the “Background Art” section of the present specification and engraved with a surface in which the irregularities of the surface of the original diffraction grating are reversed is prepared. The mold material 2 is applied. As the release material 2, silicon grease, glycerin, butyl phthalate, or the like, which has a low saturated vapor pressure and can be spread in a thin oil film, is deposited to a thickness of an order of 1/10 of the wavelength, or gold with low affinity Generally, a vapor deposition film of platinum is used. In this embodiment, silicon grease is used for the release material 2 and is applied as a thin oil film in a vacuum deposition apparatus. At the same time, a replica substrate 4 is prepared, and a resin 3 is applied on the surface thereof (FIG. 1A). Optical glass is generally used as the material of the substrate 4 and its surface is mirror-polished. Resin 3 can be made of epoxy adhesive, urea-based, melanin-based, phenol-based heat-resistant thermosetting resin, or photo-curing resin as a base material mixed with a light-absorbing substance. . In this example, a tar epoxy resin produced by mixing tar pitch and swollen charcoal as a light-absorbing substance with an epoxy resin was used, but the present invention is not limited to this. A material in which a light-absorbing substance such as black paint or carbon black is uniformly mixed can be used.

  As shown in FIG. 1B, the negative master 1 is held in a state of being pressed against the resin 3 with the release material 2 interposed therebetween, and is left until the resin 3 is completely solidified. At this time, when the thermosetting resin is the base material of the resin 3, the whole is heated. When the photocurable resin is the base material of the resin 3, the resin 3 is irradiated with light from an appropriate light source. The curing of the resin 3 is promoted.

  After the resin 3 is completely solidified and fixed to the substrate 4, the upper and lower parts are separated in the layer of the release material 2, and the residue of the release material 2 on the resin 3 is washed and removed (FIG. 1 (c)). Finally, a metal reflective film is deposited on the resin 3 with a minimum thickness so that the surface roughness does not exceed a predetermined value. In this embodiment, an aluminum film 5 is deposited as a metal reflective film to a thickness of about 100 nm. Thereby, the replica diffraction grating 6 is completed (FIG. 1C). A large number of replica diffraction gratings 6 are manufactured by repeating the procedure described above using one negative master 1.

  In the replica diffraction grating 6 manufactured according to the above manufacturing process, the thickness of the aluminum film 5 is suppressed to about 100 nm in order to make the surface roughness sufficiently small. Therefore, stray light due to the surface roughness is as much as possible. Less. In addition, the light newly transmitted to the resin 3 layer through the aluminum film 5 is absorbed by the tar pitch and swollen charcoal mixed in the resin 3, so that the light reflected / scattered in the resin 3 or the substrate 4. Does not exist, so this cannot cause stray light to increase.

  The manufacturing process is not limited to the above example. As a modification, a diffraction grating is directly or indirectly deposited on the resin layer as in the method of depositing an aluminum film in advance on the outer side of the release material 2 shown in FIG. The present invention can be applied to the method of marking the groove shape. Moreover, in the said Example, although the resin 3 is apply | coated on the board | substrate 4 made from an optical glass as shown in FIG.1 (b), the board | substrate 4 of an optical glass is not used other than this method, A method of producing a replica diffraction grating using only the resin 3 is also used, and the present invention can be applied to this method. In addition, a mold having the same shape as the groove shape of the negative master 1 in FIG. 1 is manufactured by a technique such as diamond turning, and a resin is molded by injection molding or press molding using this mold. A method of manufacturing a replica diffraction grating by vapor-depositing a metal reflective film is also used, but the present invention can also be applied to this method. Furthermore, the scope of application of the present invention is not limited to a reflective concave diffraction grating, but is applicable to all reflective replica optical elements having a metal reflective film on the surface, such as spherical mirrors, parabolic mirrors, and ellipsoidal mirrors. It is a thing.

  The present invention relates to a reflective replica optical element used in various optical instruments and measuring instruments.

It is the figure which showed the manufacture procedure of the reflection type replica diffraction grating of this invention in steps.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Negative master 2 Release material 3 Resin 4 Board | substrate 5 Aluminum film 6 Replica diffraction grating

Claims (1)

  A reflective replica optical element manufactured by transferring and replicating the shape of an original optical element directly or through a marking operation via a negative master optical element to a resin layer on a separate substrate, the resin layer A reflective replica optical element characterized by comprising a substance that absorbs light.

Images