WO2020026303A1

WO2020026303A1 - Diffraction grating

Info

Publication number: WO2020026303A1
Application number: PCT/JP2018/028458
Authority: WO
Inventors: 吉剛牧野
Original assignee: 株式会社島津製作所
Priority date: 2018-07-30
Filing date: 2018-07-30
Publication date: 2020-02-06

Abstract

A diffraction grating 100 according to the present invention has: a plurality of grating grooves 102 that are parallel with one another and that are formed in a groove forming region 101a of a grating surface 101 which is one surface of a plate-like member; and no-groove forming regions 101b in which no groove is formed, which each have a prescribed width, and which are positioned on both sides in directions in which the grating grooves extend so as to have the groove forming region 101a of the grating surface 101 interposed therebetween.

Description

Diffraction grating

The present invention relates to a diffraction grating used for various optical devices such as a spectroscope.

A spectroscope (monochromator) is a device that takes out light having a specific wavelength (monochromatic light) by dispersing the wavelength of incident light with a diffraction grating, and a general spectroscope has a housing having an entrance slit and an exit slit. And a rotation driving mechanism for changing the angle of the diffraction grating housed in the housing and the angle of the diffraction grating with respect to the light incident from the entrance slit. In the spectroscope, light of any wavelength (monochromatic light) can be extracted by adjusting the rotation position (angle) of the diffraction grating to an appropriate position, and the spectrum of the incident light can be obtained by continuously rotating the diffraction grating. Can be obtained. The rotation drive mechanism includes a drive motor such as a stepping motor and a turntable that is rotated by the drive motor, and the diffraction grating is held by a diffraction grating holder fixed to the upper surface of the turntable (Patent Document 1). reference).

FIG. 5 shows a diffraction grating holder disclosed in Patent Document 1. As shown in this figure, the diffraction grating holder 7 includes an adjusting device 30 fixed on a rotating table 8 with screws 31, a holder fixing table 32 fixed on the upper surface of the adjusting device 30, and a holder fixing table 32. Has an L-shaped front fixing plate 33 and a rear fixing plate 34 fixed to the upper surface by

screws

35 and 36.

The front fixing plate 33 and the rear fixing plate 34 include mounting

portions

33a and 34a mounted on the holder fixing base 32, and a front fixing portion 33b and a rear fixing portion 34b extending at right angles to the

mounting portions

33a and 34a, respectively. The front fixing portion 33b and the rear fixing portion 34b are arranged on the holder fixing base 32 so as to face each other. A rectangular opening 33c is formed in the front fixing portion 33b, and a portion corresponding to the opening 33c of a surface of the rear fixing portion 34b facing the front fixing portion 33b is pressed by a spring 38. A plate 37 is attached.

The diffraction grating 2 is fixed to the diffraction grating holder 7 as follows.
First, the pressing plate 37 is pressed against the rear fixing portion 34b against the elastic force of the spring 38, and the distance between the pressing plate 37 and the front fixing portion 33b is increased. Then, the diffraction grating 2 is inserted between the holding plate 37 and the front fixing portion 33b so that the grating surface faces the front fixing portion 33b. In this state, when the pressing force of the pressing plate 37 toward the rear fixing portion 34b is released, the diffraction grating 2 is pressed by the front fixing portion 33b by the pressing plate 37, whereby the diffraction grating 2 is connected to the pressing plate 37 and the front fixing portion. 33b. At this time, the position of the diffraction grating 2 is adjusted so that a region of the grating surface of the diffraction grating 2 excluding the peripheral portion is exposed from the opening 33c.

JP 2014-026013 A

(4) Light from a light source is applied to the diffraction grating 2 held by the diffraction grating holder 7 near the center of the portion exposed from the opening 33c, and wavelength-dispersed. If dirt adheres to the light irradiation area of the diffraction grating 2, the reflectance (diffraction efficiency) decreases or stray light is generated. Therefore, when attaching the diffraction grating 2 to the diffraction grating holder 7, it is necessary to pay attention so that dirt does not adhere to the grating surface, particularly to the light irradiation area.

However, in the above-described diffraction grating holder 7, since the peripheral edge of the grating surface of the diffraction grating 2 comes into contact with the outer peripheral portion of the opening 33c of the front fixing portion 33b, when a liquid material adheres to the outer peripheral portion, the May move to the periphery of the lattice plane. The liquid material is generated, for example, by condensation of moisture in the air. Since a large number of narrow grooves are formed on the grating surface of the diffraction grating, if a liquid material adheres to the periphery, it moves along the grooves (capillary phenomenon), contaminating the light irradiation area. was there.

The problem to be solved by the present invention is to provide a diffraction grating in which the liquid material attached to the peripheral edge of the grating surface does not move to other parts.

Diffraction grating according to the present invention made to solve the above problems,
A plurality of lattice grooves parallel to each other, which are formed in a groove forming region of a lattice surface that is one surface of the plate-like member,
And a non-groove-forming region having a predetermined width in which the lattice groove is not formed, which is located on both sides in the direction in which the lattice groove extends on both sides of the groove-forming region on the lattice surface.

The `` predetermined width '' of the non-groove region in the diffraction grating means that when the diffraction grating is held by the diffraction grating holder, the non-groove region is in contact with the diffraction grating holder, and the groove formation region is not The width (length) that does not touch.

With this configuration, when the diffraction grating is held by, for example, a diffraction grating holder as shown in FIG. 5, the end regions on both sides in the direction in which the grating grooves are arranged and the non-groove regions are formed on the front surface of the groove forming region. It is sandwiched between the outer peripheral portion of the opening 33c of the fixing portion 33b and the holding plate 37. At this time, even if the liquid material adhering to the front fixing portion 33b moves to the non-groove forming region, the liquid material flows to the groove forming region side because there is no lattice groove in the non-groove forming region. There is no. Further, even if the liquid material moves to the end region of the groove forming region, it moves only along the lattice groove in the end region and moves to the light irradiation region near the center of the groove forming region. There is no.

In the above-described diffraction grating, it is preferable that the upper surface of the non-groove-formed region is at a position lower than the bottom of the lattice groove. In this configuration, since a step is formed between the non-groove-forming region and the groove-forming region, it is possible to reliably prevent the liquid material attached to the non-groove-forming region from entering the groove-forming region.

By the way, when the diffraction grating is held by the diffraction grating holder having the configuration shown in FIG. 5, the end region of the groove forming region is hidden by the diffraction grating holder, so that the end region is used as a light irradiation region. There is no. Therefore, in the diffraction grating of the present invention, the grating groove may be formed in a portion of the groove forming region other than both ends in the direction in which the grating grooves are arranged.

The diffraction grating having the above configuration can be manufactured, for example, by the following method. That is, the manufacturing method of the diffraction grating according to the present invention,
Forming a release agent layer on the groove surface of the master diffraction grating having a groove surface in which a plurality of grooves parallel to each other are formed,
Forming a groove-shaped metal thin film on the release agent layer,
Bonding the replica substrate and the metal thin film via a bonding resin,
By peeling the replica substrate from the master diffraction grating, on the replica substrate, a bonding resin layer having a groove surface of the inverted shape of the groove surface, a replica diffraction grating having a metal thin film covering the surface thereof A step of making;
Cutting the end regions on both sides of the groove surface of the replica diffraction grating in the direction in which the groove extends.

In the above method, after a replica diffraction grating is obtained by a general replica diffraction grating manufacturing method, the diffraction grating of the present invention is obtained by cutting two end regions of the groove surface of the replica diffraction grating. As a means for cutting the groove surface, for example, a cutting machine or a grinder such as a dicing saw (dicing blade) used for cutting out an integrated circuit from a silicon wafer can be used. An advantage of using a dicing saw is that the end region can be cut in the same step as the step of cutting the diffraction grating into a desired size. Further, in a case where a region where a groove is not formed is wide and it takes too much time to perform cutting by a cutting machine, a grinder may be used. The processing time can be reduced by simultaneously removing a wide range of grooves by grinding with a grinder.

Further, another manufacturing method of the diffraction grating according to the present invention,
Forming a release agent layer on the groove surface of the master diffraction grating having a groove surface including a groove forming region in which a plurality of grooves parallel to each other are formed, and a groove non-forming region on both sides of the groove forming region; The process of
Forming a groove-shaped metal thin film on the release agent layer,
Bonding the replica substrate and the metal thin film via an adhesive resin,
By peeling the replica substrate from the master diffraction grating, on the replica substrate, a step of forming an adhesive resin layer having a groove surface of the inverted shape of the groove surface, and forming a metal thin film covering the surface. It is characterized by having.

In the above method, a master diffraction grating having a groove surface corresponding to the grating surface of the diffraction grating according to the present invention is used instead of the master diffraction grating used in the conventional method of manufacturing a replica diffraction grating. According to the above method, it is necessary to produce a master diffraction grating having a shape different from the conventional one. However, once the master diffraction grating is produced, the diffraction grating according to the present invention can be easily produced.

According to the diffraction grating of the present invention, it is possible to prevent the liquid material attached to the peripheral portion of the grating surface from spreading to other portions, so that the diffraction efficiency is reduced when this diffraction grating is incorporated in a spectroscope. It is possible to prevent dripping and stray light from being generated.

FIG. 4 is a view showing a manufacturing process of the diffraction grating according to one embodiment of the present invention. 1 is a perspective view of a diffraction grating according to one embodiment of the present invention. 1 is a plan view of a diffraction grating according to one embodiment of the present invention. FIG. 11 is a perspective view of a master diffraction grating used in a method for manufacturing a diffraction grating according to a modification of the present invention. FIG. 13 is a plan view of a diffraction grating according to another modification of the present invention. The figure which shows the state in which the diffraction grating is hold | maintained by the general diffraction grating holder.

Hereinafter, examples of the diffraction grating and the manufacturing method according to the present invention will be described.
FIG. 1 is a schematic view showing a manufacturing process of a diffraction grating according to an embodiment of the present invention.
First, a flat glass substrate 111 made of quartz glass or the like is prepared. The flat glass substrate 111 is a parallel flat substrate having an even thickness and an upper surface and a lower surface being parallel. A photoresist is coated on the flat glass substrate 111, and a portion of the photoresist corresponding to the lattice groove is removed by a holographic exposure method or the like.

(4) Next, lattice grooves are formed by ion beam etching or the like using the resist pattern as a mask so that the groove cross section has a sawtooth shape with a predetermined blaze angle. An aluminum thin film 112 having a thickness of about 0.2 μm is formed thereon by vacuum evaporation, and a master diffraction grating 110 having a grating groove whose surface is covered with the aluminum thin film 112 is completed ({state of FIG. 1A)). . Usually, the surface roughness at this time can be about 0.5 nm RMS.

Subsequently, an oil film 113 made of silicon grease or the like as a release agent is formed on the grating surface of the master diffraction grating 110 (the state shown in FIG. 1B), and then an aluminum thin film 123 is formed by vacuum evaporation (FIG. 1 (c)). This aluminum thin film 123 is to cover the grating surface of the replica diffraction grating later, and the film thickness may be, for example, about 0.2 μm.

Next, a replica substrate 121, which is a parallel plane substrate made of soda glass, is prepared (the state shown in FIG. 1D). Then, after cleaning the surface 121a of the replica substrate 121 on which the adhesive 122 is to be applied (the surface on the grid surface side) 121a, the adhesive (剤 thermosetting epoxy resin) 122 is applied to a substantially uniform thickness (FIG. 1E). State). Then, the replica substrate 121 and the master diffraction grating 110 in the state shown in FIG. 1C are pasted together via the adhesive 122 and pressed with an appropriate pressure. Thereby, the adhesive 122 # spreads so as to fill the groove having the sawtooth cross section of the aluminum thin film 123 (the state of FIG. 1F).

{Circle around (2)} This is placed in a baking oven, and heat is applied at a predetermined temperature for a predetermined time to accelerate curing of the adhesive 122. When the adhesive 122 is sufficiently cured, the replica substrate 121 is peeled off from the master diffraction grating 110 with the oil film 113 serving as a release agent as a boundary. Then, the aluminum thin film 123 formed in a saw-tooth cross section is peeled off while being bonded to the replica substrate 121 via the adhesive 122 (the state shown in FIG. 1G). As a result, a replica diffraction grating 120 in which a grating groove obtained by reversely transferring the grating groove of the master diffraction grating 110 is formed is obtained.

Next, the surface (lattice surface) of the replica diffraction grating 120 having the lattice grooves is directed upward, and both ends of the surface in the direction in which the lattice grooves extend are cut by a cutting machine (FIG. 1 (h)). FIG. 1H shows a state where the both end portions are cut by a blade 130 of a dicing saw. FIG. 1H shows an example in which the adhesive 122 and the aluminum thin film 123 covering the surface are cut out of the both end portions, but the aluminum thin film 123 and the adhesive 122 and the flat glass substrate 111 are cut. A part of the surface may be cut.

After cutting, the cut portion is ground and polished, and the whole is washed, whereby the diffraction grating 100 according to the present embodiment is completed (see FIGS. 2 and 3). Although the residue of the oil film 13 is not shown in FIG. 1G, the oil film 113 remains on both surfaces when the master diffraction grating 110 and the replica diffraction grating 120 are separated. The oil film 113 remains until after cutting both end portions of the grating surface of the replica diffraction grating 120, but is removed by washing.

As shown in FIGS. 2 and 3, the diffraction grating 100 has a grating surface 101 including a groove forming region 101a and two non-groove forming regions 101b located on both sides of the groove forming region 101a. I have. The non-groove forming region 101b is formed by cutting both end portions of the grating surface of the replica diffraction grating 120, and the uncut portion becomes the groove forming region 101a. Therefore, in the groove forming region 101a, the lattice grooves 102 extending in the direction from one groove non-forming region 101b to the other groove non-forming region 101b are formed, and the lattice grooves are formed in the groove non-forming region 101b. Not formed. In addition, the upper surface of the non-groove forming region 101b is at a position lower than the bottom (deepest) of the lattice groove 102.

As a cutting machine, by using an automatic dicing saw manufactured by DISCO Co., Ltd., for example, a groove forming area with a width of 64 mm and a non-groove forming area with a width of 6 mm on the grating surface of a vertical 70 mm x horizontal 70 mm x 6 mm thick diffraction grating. (3 mm width non-groove-forming regions on both sides) could be formed.

It should be noted that the present invention is not limited to the above-described embodiment, and appropriate changes can be made.
For example, in the above embodiment, the non-groove-forming region is formed by cutting a predetermined portion of the replica diffraction grating with a cutter, but the master having a groove surface having a shape corresponding to the groove-forming region and the non-groove-forming region is formed. The diffraction grating of the present invention may be manufactured using a diffraction grating. An example of such a master diffraction grating 200 is shown in FIG. The master diffraction grating 200 has a groove surface 201 including a groove forming region 201a and non-groove forming regions 201b on both sides of the groove forming region 201a. A groove having a sawtooth cross section is formed in the groove forming region 202a, and the upper surface of the groove non-forming region 202b is located higher than the top of the groove in the groove forming region 201a. Such a master diffraction grating 200 can be manufactured by a method similar to that of the master diffraction grating 110 described above.

The procedure for manufacturing a diffraction grating using the above master diffraction grating 200 is as follows. First, an oil film 113 and an aluminum thin film 123 are formed on the surface of the master diffraction grating 200 (see FIGS. 1B and 1C), and a replica substrate 121 coated with an adhesive 122 is bonded thereon. The adhesive 122 is cured (see FIGS. 1D to 1F). Thereafter, the replica substrate 121 is peeled off (see FIG. 1 (g)). As a result, a replica diffraction grating having substantially the same shape as the diffraction grating 100 shown in FIGS. 2 and 3 is obtained. That is, in this example, the replica diffraction grating becomes the diffraction grating according to the present invention as it is, and the cutting step is unnecessary.

In the above embodiment, the lattice grooves are formed in the entire groove forming region. However, the lattice grooves may not be formed at both ends of the groove forming region in the direction in which the lattice grooves are arranged. FIG. 5 shows an example of such a diffraction grating. As shown in FIG. 5, the grating surface 301 of the diffraction grating 300 has a groove forming region 301a and a groove non-forming region 301b surrounding the groove forming region 301a. In this case, the non-groove forming region 301b can be formed by cutting the peripheral edge of a diffraction grating having a grating groove over the entire grating surface. Alternatively, it may be manufactured using a master diffraction grating having a groove surface having a shape corresponding to the grating surface of the diffraction grating shown in FIG.

In each of the above-described diffraction gratings, the upper surface of the non-groove region is lower than the bottom of the lattice groove, but the upper surface of the non-groove region may be higher than the bottom of the lattice groove.
In addition, the present invention is not limited to the replica diffraction grating, and can be applied to a so-called machined diffraction grating that forms a grating groove by cutting the surface of a flat glass substrate with a cutting machine.
Further, the present invention is not limited to a grating having a flat grating surface, but can be applied to a diffraction grating having a curved surface, for example, a concave grating or a toroidal grating.

100, 300: Diffraction grating 101, 301:

Grating surface

101a, 301a: Groove forming

region

101b, 301b: Groove non-forming region 102: Groove 120: Replica diffraction grating 200: Master diffraction grating 201: Groove surface 201a: Groove forming region 201b ... Area without grooves

Claims

A plurality of lattice grooves parallel to each other, which are formed in a groove forming region of a lattice surface that is one surface of the plate-like member,
A diffraction grating, comprising: a non-groove-forming region having a predetermined width in which a lattice groove is not formed, which is located on both sides of the lattice forming region on the lattice surface in the direction in which the lattice groove extends.
The diffraction grating according to claim 1,
A diffraction grating, wherein an upper surface of the non-groove forming region is located at a position lower than a bottom of the groove.
The diffraction grating according to claim 1,
The diffraction grating, wherein the grating groove is formed in a portion of the groove forming region other than both ends in the direction in which the grating grooves are arranged.
It is a manufacturing method of the diffraction grating of Claim 1, Comprising:
Forming a release agent layer on the groove surface of the master diffraction grating having a groove surface in which a plurality of grooves parallel to each other are formed,
Forming a groove-shaped metal thin film on the release agent layer,
Bonding the replica substrate and the metal thin film via a bonding resin,
By peeling the replica substrate from the master diffraction grating, on the replica substrate, a bonding resin layer having a groove surface of the inverted shape of the groove surface, a replica diffraction grating having a metal thin film covering the surface thereof A step of making;
Cutting the two end regions of the groove surface of the replica diffraction grating that face each other in the direction in which the grooves extend.
It is a manufacturing method of the diffraction grating of Claim 1, Comprising:
Forming a release agent layer on the groove surface of the master diffraction grating having a groove surface including a groove forming region in which a plurality of grooves parallel to each other are formed, and a groove non-forming region on both sides of the groove forming region; The process of
Forming a groove-shaped metal thin film on the release agent layer,
Bonding the replica substrate and the metal thin film via an adhesive resin,
By peeling the replica substrate from the master diffraction grating, on the replica substrate, a step of forming an adhesive resin layer having a groove surface of the inverted shape of the groove surface, and forming a metal thin film covering the surface. A method for manufacturing a diffraction grating.