JP2022132297A - Concave diffraction grating, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concave diffraction grating capable of improving diffraction efficiency by suppressing the spherical aberration.

SOLUTION: A concave diffraction grating 2 is a concave diffraction grating 2 that disperses and condenses light. The concave diffraction grating has sawtooth-shaped lattice grooves 21 formed on a concave substrate 24 in which the intervals between the sawtooth-shaped lattice grooves 21 are unequal. In the concave diffraction grating 2 that disperses and condenses light, a sawtooth shape is formed on a planar substrate by photolithography, etching, or machining. A planar diffraction grating having grating grooves 21 with unequal intervals of sawtooth shape is deformed on a convex fixed substrate and is formed by transferring the mold of the mounted concave diffraction grating to the surface of metal or resin.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a concave diffraction grating and its manufacturing method, and more particularly to a curved diffraction grating for splitting and converging light and an optical device using the same.

As background art in this technical field, a curved diffraction grating, which is an optical element mounted in an optical device such as a spectrophotometer, has the performance of both light dispersion and convergence. It is possible to simplify the configuration of

Conventionally, in a spherical concave diffraction grating, if the intervals between the grating grooves are equal, the spectroscopic light is focused on the Rowland circle. It is possible to let However, installing the detector on the Rowland circle raises concerns about an increase in the size of the optical device. Therefore, by setting the grating grooves formed on the concave diffraction grating at unequal intervals, the light collection position, that is, the installation position of the detector can be corrected from the Rowland circle to an approximately linear position, and the optical device can be miniaturized. In order to realize such a spherical concave diffraction grating, for example, methods described in Patent Documents 1, 2, and 3 have been proposed.

Concave diffraction gratings are manufactured by creating a concave diffraction grating mold by stamping grating grooves on a convex substrate with a machine such as a ruling engine, and transferring the stamped grating grooves to resin, metal, etc. is doing. In a spherical concave diffraction grating, as described in Japanese Patent Application Laid-Open No. 2002-200002, the aberration of spectral light is suppressed by making the intervals between grating grooves unequal.
In Patent Document 2, a resist is formed on a concave substrate with grating grooves at unequal intervals, and laminar (rectangular) grating grooves are formed by ion etching to fabricate a concave diffraction grating. In Patent Document 3, a planar diffraction grating having sawtooth-shaped grating grooves is sandwiched between uneven substrates, deformed, and bonded to a convex substrate to form a concave diffraction grating mold. The mold for the concave diffraction grating is transferred to metal, resin, or the like to fabricate the concave diffraction grating.

JP-A-55-13918 JP 2011-106842 A WO2016/059928

In a spherical concave diffraction grating, if the intervals between the grating grooves are equal, the spectral light will be focused on the Rowland circle. is possible. However, installing the detector on the Rowland circle raises concerns about an increase in the size of the optical device. Therefore, by setting the grating grooves formed on the concave diffraction grating at unequal intervals, the light collection position, that is, the installation position of the detector, can be corrected from the Rowland circle to an approximately linear position, and the optical device can be miniaturized. There are the following issues.

In the method of manufacturing a concave diffraction grating described in Patent Document 1, if a diffraction grating mold is produced by a method of marking a convex substrate with a machine such as a ruling engine, the angle of the marking tool is constant, so the center of the curved substrate A problem is that the blaze angle is not constant because shallow and deep portions are formed in the sawtooth-shaped grating grooves at the edges and edges.

In the method of manufacturing a curved diffraction grating using a semiconductor process described in Patent Document 2, it is difficult to accurately produce a grating groove pattern of a resist by photolithography for an arbitrary curved substrate. In the case of etching to the curved surface, there may be a problem that laminar-type (rectangular) grating grooves having an inclination from the perpendicular to the curved surface are formed.

In the technique of manufacturing a mold for a curved diffraction grating described in Patent Document 3, after forming sawtooth grating grooves on a flat substrate, the blaze angle is maintained even at the center and end portions of the curved substrate because it is bonded to the curved surface. Although it is possible to fabricate a constant concave diffraction grating, since the grating grooves are equally spaced, the suppression of aberration is insufficient, and the diffraction efficiency is lowered, so that the detected light cannot be effectively utilized.

Further, if the laminar diffraction grating described in Patent Document 2 is fabricated on a flat substrate and the method described in Patent Document 3 is applied, there is no inclination in the direction perpendicular to the curved surface, and the gratings are arranged at unequal intervals. A curved diffraction grating having rectangular grating grooves can be produced, but if it is sandwiched between uneven substrates and a load is applied, the load may be applied to the rectangular grating grooves and damage the rectangular grating grooves. In addition, when the mold for the concave diffraction grating is transferred, the rectangular grating grooves are caught in the mold, so there is a problem that the concave diffraction grating is difficult to separate from the mold.

Accordingly, the present invention provides a concave diffraction grating capable of improving diffraction efficiency by suppressing spherical aberration, and a method of manufacturing the same.

In order to solve the above problems, a concave diffraction grating according to the present invention is a concave diffraction grating that disperses and converges light, has sawtooth-shaped grating grooves on a concave substrate, and comprises: It is characterized in that the intervals between the grooves are unequal, the intervals between the grating grooves are reduced equidistantly in the blaze direction, and the reflecting surface of the concave diffraction grating forms a part of a spherical surface. do.

Further, a concave diffraction grating according to the present invention is a concave diffraction grating that disperses and converges light, has sawtooth grating grooves on a concave substrate, and the intervals between the sawtooth grating grooves are irregular. etc., in which the spacing between adjacent grating grooves gradually changes from wide to narrow along the blaze direction, and the reflecting surface of the concave diffraction grating forms part of a spherical surface. It is characterized by

Further, the method for manufacturing a concave diffraction grating according to the present invention includes: (1) forming a sawtooth shape on a planar substrate by photolithography and etching or machining, and forming grating grooves at uneven intervals; (2) a step of fabricating a planar diffraction grating substrate by forming a planar diffraction grating substrate having a shape in which the intervals between are equally reduced in the blaze direction and having a constant blaze angle; (3) installing a concave substrate so that the concave surface faces the surface, and placing the convex substrate through an adhesive layer so that the convex surface faces the surface opposite to the surface on which the grating grooves are formed; (4) a bonding step of making the surface of the planar diffraction grating substrate on which the grating grooves are formed conform to the concave substrate, and bonding the planar diffraction grating substrate to the convex substrate by the adhesive layer; (5) removing the outer peripheral portion of the planar diffraction grating substrate extending outside the convex surface of the convex substrate after the concave substrate is removed, and forming a concave diffraction grating mold; ) A step of transferring the mold of the concave diffraction grating having a shape in which the intervals of the grating grooves are equally reduced in the blaze direction and the reflection surface of the concave diffraction grating forming a part of a spherical surface, onto the surface of metal or resin. and.

In addition, the method for manufacturing a concave diffraction grating according to the present invention includes: (1) forming a sawtooth shape on a planar substrate by photolithography and etching or machining, and forming unevenly spaced grating grooves mutually (2) fabricating a planar diffraction grating substrate by forming a shape in which the spacing between adjacent grating grooves gradually changes from a wide spacing to a narrow spacing along the blaze direction; A concave substrate is installed so that the concave surface faces the surface on which the grating grooves are formed, and a convex substrate is installed via an adhesive layer so that the convex surface faces the surface opposite to the surface on which the grating grooves are formed. and (3) making the surface of the planar diffraction grating substrate on which the grating grooves are formed conform to the concave substrate, and bonding the planar diffraction grating substrate to the convex substrate by the adhesive layer. (4) after the concave substrate is removed, an outer peripheral portion of the planar diffraction grating substrate extending outside the convex surface of the convex substrate is removed to form a concave diffraction grating mold; (5) the interval between grating grooves adjacent to each other has a shape in which the interval between the grating grooves is gradually changed from wide to narrow along the blaze direction, and the reflecting surface of the concave diffraction grating is spherical. and transferring the mold of the concave diffraction grating forming a part to the surface of metal or resin.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the concave-surface diffraction grating which can improve diffraction efficiency by suppressing a spherical aberration, and its manufacturing method.
Further, according to the present invention, the diffraction efficiency can be improved by suppressing spherical aberration by mounting a concave diffraction grating having a sawtooth shape with a constant blaze angle and provided with unevenly spaced grating grooves in an optical device. In addition, it is possible to provide an optical device in which the detector can be installed in a straight line.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an overall schematic configuration diagram of an optical device using a concave diffraction grating of Example 1 according to an embodiment of the present invention; FIG. 2 is a perspective view showing a schematic configuration of a concave diffraction grating (spherical diffraction grating) shown in FIG. 1; FIG. FIG. 3 is an AA cross-sectional view of the concave diffraction grating (spherical diffraction grating) shown in FIG. 2 and an enlarged view of grating grooves. FIG. 10 is a perspective view showing a schematic configuration of a concave diffraction grating (spherical diffraction grating) mold of Example 2 according to another example of the present invention; FIG. 5 is a cross-sectional view taken along line BB of the concave diffraction grating (spherical diffraction grating) type shown in FIG. 4; FIG. 6A is a diagram showing a method of manufacturing a concave diffraction grating using the concave diffraction grating mold shown in FIG. 4, FIG. FIG. 6(c) shows the step of forming a metal layer on the grating mold, FIG. 6(c) shows the step of placing a concave substrate on the metal layer, and FIG. It is a figure which shows a process. 7(a) shows a step of forming a metal diffraction grating, and FIG. FIG. 7(c) shows the bonding step, FIG. 7(d) shows the step of removing the concave substrate, and FIG. 7(e) shows the metal diffraction grating. FIG. 10 is a diagram showing a process of obtaining a mold for a concave diffraction grating by removing the outer periphery of the manufactured diffraction grating; 8(a) shows a step of forming a planar diffraction grating, and FIG. FIG. 8(c) shows the step of peeling off the metal diffraction grating from the planar diffraction grating, and FIG. 8(d) shows the process of removing the concave substrate above the metal diffraction grating and the convex substrate below the metal diffraction grating. FIG. 8(e) is the bonding step, FIG. 8(f) is the step of removing the concave substrate, and FIG. 8(g) is the removal of the outer periphery of the metal diffraction grating. It is a figure which shows the process of obtaining a type|mold. 9A and 9B are diagrams showing a method of manufacturing a concave diffraction grating mold of Example 5 according to another example of the present invention, FIG. FIG. 9(c) shows the bonding step, FIG. 9(d) shows the step of removing the concave substrate, and FIG. 9(e) shows the metal diffraction grating. FIG. 10 is a diagram showing a process of obtaining a mold for a concave diffraction grating by removing the outer periphery of the manufactured diffraction grating; 10(a) shows a step of forming a plane diffraction grating, and FIG. 10(b) shows a method of manufacturing a concave diffraction grating mold according to a sixth embodiment of the present invention. FIG. 10(c) shows the step of forming a metal diffraction grating, and FIG. 10(d) shows the step of placing a concave substrate above and a convex substrate below the metal diffraction grating. 10(e) shows the bonding step, FIG. 10(f) shows the step of removing the concave substrate, and FIG. 10(g) shows the step of removing the outer periphery of the metal diffraction grating to obtain a concave diffraction grating mold. It is a diagram.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall schematic configuration diagram of an optical device using a concave diffraction grating of Example 1 according to one embodiment of the present invention. The optical device 1 is used for concentration measurement and substance identification by selectively absorbing light of wavelengths specific to chemical bonds in chemical substances, biological substances, and the like. As shown in FIG. 1, the optical device 1 includes a white light source 11, a condenser lens 12a, a sample chamber 13, a condenser lens 12b, a slit 14, a concave diffraction grating 2, and a plurality of linearly arranged detectors 16. Consists of
The light from the white light source 11 is condensed by the condensing lens 12 a and irradiated to the measurement object in the sample chamber 13 . Light transmitted from the sample chamber 13 is condensed onto the opening of the slit 14 by the condensing lens 12b. The light passing through the slit 14 is wavelength-dispersed by the concave diffraction grating 2 to form a spectrum. The formed spectrum is detected by detector 16 .

The concave diffraction grating 2 will be explained. 2 is a perspective view showing a schematic configuration of the concave diffraction grating 2 shown in FIG. 1, and FIG. 3 is a cross-sectional view of the concave diffraction grating 2 shown in FIG. 2 taken along line AA and an enlarged view of grating grooves. As shown in FIGS. 2 and 3, the concave diffraction grating 2 includes a concave substrate 24 having an arbitrary curvature, a metal layer 22 having grating grooves 21 formed therein, and a resin layer fixing the metal layer 22 on the concave substrate 24. 23. The reflecting surface (surface) of the concave diffraction grating is part of a sphere. Therefore, the concave diffraction grating is sometimes called a spherical diffraction grating. A concave grating with equally spaced grating grooves images on the Rowland circle. On the other hand, as shown in FIG. 3, in the concave diffraction grating 2 in which the intervals of the grating grooves 21 are reduced in the blaze direction, an image can be formed approximately on a straight line. In other words, in the concave diffraction grating 2 in which the intervals between the grating grooves 21 are reduced stepwise along the blaze direction, an image can be formed approximately on a straight line. Here, the blaze direction is defined as the direction from the apex angle 211 of the sawtooth-shaped grating groove 21 to the vertex having the minimum angle (blaze angle 212), as shown in FIG. Therefore, along the blaze direction, the interval between adjacent grating grooves 21 gradually changes from wide to narrow.

A plurality of detectors 16 can be arranged in a straight line by applying the concave diffraction grating 2 that is reduced in the blaze direction equidistantly to the optical device 1 shown in FIG. can be simplified, and the optical device 1 can be miniaturized.
In addition, since the concave diffraction grating 2 has a constant blaze angle 212, it is possible to selectively disperse light of a specific wavelength, so that the optical device 1 can be made with little noise (stray light), and the detection efficiency can be improved. .

As described above, according to this embodiment, it is possible to provide a concave diffraction grating capable of improving diffraction efficiency by suppressing spherical aberration.
In addition, according to the present embodiment, by mounting a concave diffraction grating having a sawtooth shape with a constant blaze angle and including grating grooves at uneven intervals in an optical device, spherical aberration is suppressed and diffraction efficiency is improved. It is possible to provide an optical device which can be installed in a straight line and which can be installed in a straight line.
Moreover, according to this embodiment, the detector can be installed in a straight line, so that a compact optical device can be realized.
Furthermore, a low-cost optical device with a small number of optical elements can be realized.

The structure of the concave diffraction grating mold and the manufacturing method of the concave diffraction grating will be described with reference to FIGS. 4 to 6. FIG. FIG. 4 is a perspective view showing a schematic configuration of a concave diffraction grating mold of Embodiment 2 according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view of the concave diffraction grating mold shown in FIG. is.

As shown in FIGS. 4 and 5, the concave diffraction grating mold 3 includes a convex substrate 34 having an arbitrary curvature, a metal diffraction grating 32 which is a metal film in which grating grooves 31 are formed, and a It is composed of an adhesive layer 33 that fixes a metal diffraction grating 32, which is a metal film. As shown in FIG. 5, the intervals of the grating grooves 31 of the metal diffraction grating 32 forming the mold 3 of the concave diffraction grating are expanded equally in the blaze direction. In other words, the intervals between the grating grooves 31 of the metal diffraction grating 32 are increased stepwise along the blaze direction. Therefore, along the blaze direction, the metal diffraction grating 32 constituting the mold 3 of the concave diffraction grating has a shape in which the spacing between adjacent grating grooves 31 gradually changes from narrow to wide. have.

Next, the manufacturing direction of the concave diffraction grating 2 shown in the first embodiment will be described. 6A and 6B show a method of manufacturing a concave diffraction grating using the concave diffraction grating mold shown in FIG. ) shows the step of forming a metal layer on a concave diffraction grating mold, FIG. 6C shows the step of placing a concave substrate on the metal layer, and FIG. It is a figure which shows the process of obtaining a diffraction grating.

In the step of preparing the mold for the concave diffraction grating shown in FIG. 6A, first, the mold 3 for the concave diffraction grating having the sawtooth-shaped grating grooves 31 is prepared.
Next, in the step of forming a metal layer on the concave diffraction grating mold shown in FIG. A metal layer 22 is formed. In the step of placing the concave substrate on the metal layer shown in FIG. 6C, after forming the resin layer 23 on the metal layer 22 , the concave substrate 24 is placed on the resin layer 23 .

In the process of obtaining a concave diffraction grating by peeling from the concave diffraction grating mold shown in FIG. The concave diffraction grating 2 is manufactured by removing (separating) the .

Alternatively, the metal layer 22 may be formed on the surface of the resin layer 23 after the grating grooves 31 are transferred to the resin layer 23 by a technique such as nanoimprinting using the concave diffraction grating mold 3 . Here, since the concave diffraction grating 2 is formed by transferring the mold 3 of the concave diffraction grating, as shown in the right diagram of FIG. That is, in order to form the concave diffraction grating 2 that is reduced equidistantly in the blaze direction (the blaze direction of the concave diffraction grating 2), the spacing of the grating grooves 31 of the mold 3 of the concave diffraction grating must be changed from the apex angle 311 to Towards the vertex of the blaze angle 312, that is, it should be formed to expand proportionally in the blaze direction (the blaze direction of the mold 3 of the concave diffraction grating).

As described above, according to this embodiment, it is possible to easily manufacture the concave diffraction grating 2 shown in the first embodiment.

Next, a method for manufacturing a concave diffraction grating mold will be described. A plurality of manufacturing methods described below can be used for manufacturing a concave diffraction grating represented by the above spherical diffraction grating.

7A and 7B are diagrams showing a method of manufacturing a mold for a concave diffraction grating of Example 3 according to another example of the present invention. FIG. (b) shows the step of placing a concave substrate above the metal diffraction grating and a convex substrate below, FIG. 7(c) shows the bonding step, FIG. 7(d) shows the step of removing the concave substrate, e) is a diagram showing a step of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating.

In the step of forming the metal diffraction grating shown in FIG. 7(a), grating grooves 31 having a saw-tooth shape and expanding equidistantly in the blaze direction are mechanically stamped on a flat metal substrate. A metal diffraction grating 32 is formed. In other words, the intervals between the grating grooves 31 of the metal diffraction grating 32 are increased stepwise along the blaze direction. Therefore, along the blaze direction, the metal diffraction grating 32 has a shape in which the spacing between adjacent grating grooves 31 gradually changes from narrow spacing to wide spacing.

Next, in the step of placing a concave substrate above the metal diffraction grating and a convex substrate below the metal diffraction grating shown in FIG. , the adhesive layer 33 and the convex substrate 34 are placed on the surface opposite to the surface on which the grating grooves 31 are formed. That is, the concave surface of the concave substrate 35 is placed above the surface of the metal diffraction grating 32 on which the grating grooves 31 are formed, and the concave surface of the metal diffraction grating 32 is placed on the side opposite to the surface of the metal diffraction grating 32 on which the grating grooves 31 are formed. The adhesive layer 33 is placed below the surface, and the convex surface of the convex substrate 34 is placed below the adhesive layer 33 so as to face each other.

In the bonding process shown in FIG. 7(c), a temperature higher than the softening point of the bonding layer 33 and a load are applied in a vacuum atmosphere, and the surface of the metal diffraction grating 32 on which the grating grooves 31 are formed is placed on the concave substrate 35. Along with this, the metal diffraction grating 32 is adhered to the convex surface of the convex substrate 34 by the adhesive layer 33 .
Next, in the step of removing the concave substrate shown in FIG. 7D, the adhesive layer 33 is cured by cooling while the load is applied, and the concave substrate 35 is removed (removed). Subsequently, in the process of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating shown in FIG. The mold 3 of the concave diffraction grating is formed by removing the outer peripheral portion of the grating 32 extending outside the convex surface of the convex substrate 34 .
By deforming the metal diffraction grating 32 into a curved surface following the concave substrate 35 , the surface on which the grating grooves 31 are formed has the surface accuracy of the concave substrate 35 . Further, the adhesive layer 33 is softened at the time of adhesion, and can absorb the effects of variations in the thickness of the metal diffraction grating 32 and variations in surface precision of the convex substrate 34 .

A metal diffraction grating 32 in which grating grooves 31 are formed on a metal plane substrate by mechanical marking or semiconductor processes (photolithography and etching), or a plane diffraction grating in which grating grooves 31 are formed by mechanical marking or semiconductor processes. A metal diffraction grating 32 is fabricated by transferring the grating to a metal flat substrate. Sputtering, vapor deposition, and plating are used to transfer the grating grooves of the planar diffraction grating to the metal planar substrate. By deforming these metal diffraction gratings 32 into curved surfaces and mounting them on a convex substrate 34, a concave diffraction grating mold 3 is produced. This concave diffraction grating mold 3 is transferred to the metal layer 22 and the resin layer 23 by the method shown in FIG.

When the grating grooves 31 are formed on a flat substrate by mechanical marking, since the angle of the marking tool is constant, the sawtooth-shaped grating grooves 31 having a constant blaze angle 312 can be formed over the entire surface of the substrate with little variation in shape. can be formed.
When the grating grooves 31 are formed on a flat substrate by a semiconductor process, compared with photolithography and etching on a curved surface, the sawtooth shaped grating grooves 31 having a constant blaze angle 312 (FIG. 6) can be formed with less variation in shape. It is easy to form and can be applied to conventional photolithography and etching equipment. The planar diffraction grating substrate (metal diffraction grating) 32 produced by these methods is deformed into a curved surface and mounted on the convex substrate 34, so that the entire surface of the curved surface (convex surface) has a sawtooth shape with a substantially constant blaze angle. and having grating grooves 31 equidistantly spaced in the blaze direction.

When deforming the metal diffraction grating 32 into a curved surface and mounting it on the convex substrate 34, the metal diffraction grating 32 is sandwiched between a concave substrate 35 having high surface accuracy and a convex substrate 34, and a load and temperature are applied. , to fabricate the mold 3 of the concave diffraction grating. By making the surface of the metal diffraction grating 32 on which the grating grooves 31 are formed follow the concave substrate 35, variations in substrate thickness of the metal diffraction grating 32 and an adhesive layer for fixing the metal diffraction grating 32 and the convex substrate 34 are suppressed. The surface accuracy of the mold 3 for the concave diffraction grating can be improved without being affected by variations in the thickness of 33 and surface accuracy of the convex substrate. When the metal diffraction grating 32 is sandwiched between the concave substrate 35 and the convex substrate 34 and is deformed into a curved surface by applying a load, the grating grooves 31 may be deformed or crushed. Since the load applied to the grooves 31 is distributed in the direction adjacent to the apex angle 311 (FIG. 6) of the sawtooth-shaped grating grooves 31, the mold 3 of the concave diffraction grating can be manufactured without being deformed or crushed.

As described above, according to this embodiment, the concave diffraction grating has a sawtooth shape with a substantially constant blaze angle on the entire curved surface (convex surface), and has grating grooves 31 whose intervals are changed equally in the blaze direction. It becomes possible to produce the mold 3 of As a result, it is possible to fabricate a concave diffraction grating 2 having a transcribed sawtooth shape with a substantially constant blaze angle.
Further, according to this embodiment, it is possible to improve the surface precision of the mold 3 of the concave diffraction grating.

8A and 8B are diagrams showing a method of manufacturing a concave diffraction grating mold according to Embodiment 4 of another embodiment of the present invention. FIG. b) shows a step of forming a metal diffraction grating, FIG. 8(c) shows a step of separating the metal diffraction grating from the planar diffraction grating, and FIG. 8(e) is the bonding step, FIG. 8(f) is the step of removing the concave substrate, and FIG. 8(g) is the removal of the outer periphery of the metal diffraction grating. FIG. 10 illustrates the process of obtaining a mold for a concave diffraction grating;

In the step of forming the planar diffraction grating shown in FIG. 8A, the sawtooth grating grooves 41a are reduced equally in the blaze direction by mechanical marking on the planar substrate, thereby forming the planar diffraction grating 40. Form. In other words, the interval between the grating grooves 41a of the planar diffraction grating 40 is reduced stepwise along the blaze direction. Accordingly, along the blaze direction, the planar diffraction grating 40 has a shape in which the spacing between adjacent grating grooves 41a gradually changes from wide to narrow in steps.

Next, in the step of forming a metal diffraction grating shown in FIG. 8B, after forming a seed film on the surface on which the grating grooves 41a are formed, metal is laminated by electroplating to form a metal diffraction grating. A grid 42 is formed.
In the step of removing the metal diffraction grating from the planar diffraction grating shown in FIG. 8C, the seed film is etched from the planar diffraction grating 40 to remove the metal diffraction grating 42 . Here, the sawtooth-shaped grating grooves 41b of the metal diffraction grating 42 are formed at intervals that are expanded equidistantly in the blaze direction. In other words, the intervals between the grating grooves 41b of the metal diffraction grating 42 are increased stepwise along the blaze direction. Accordingly, along the blaze direction, the metal diffraction grating 42 has a shape in which the spacing between adjacent grating grooves 41b gradually changes in stages from narrow to wide.

Next, in the step of placing a concave substrate above the metal diffraction grating and a convex substrate below the metal diffraction grating shown in FIG. , an adhesive layer 43 and a convex substrate 44 are placed on the surface opposite to the surface on which the grating grooves 41b are formed. That is, the concave surface of the concave substrate 45 is placed above the surface of the metal diffraction grating 42 on which the grating grooves 41b are formed, and the concave surface of the metal diffraction grating 42 on the side opposite to the surface of the metal diffraction grating 42 on which the grating grooves 41b are formed. The adhesive layer 43 is placed below the surface, and the convex surface of the convex substrate 44 is placed below the adhesive layer 43 so as to face each other.

In the bonding step shown in FIG. 8(e), a temperature higher than the softening point of the bonding layer 43 and a load are applied in a vacuum atmosphere, and the surface of the metal diffraction grating 42 on which the grating grooves 41b are formed is placed on the concave substrate 45. The metal diffraction grating 42 is adhered to the convex surface of the convex substrate 44 by means of the adhesive layer 43 .

Next, in the step of removing the concave substrate shown in FIG. 8F, the concave substrate 45 is removed (removed) after the adhesive layer 43 is cured by cooling while the load is applied. Subsequently, in the process of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating shown in FIG. The mold 4 of the concave diffraction grating is formed by removing the outer peripheral portion of the grating 42 extending outside the convex surface of the convex substrate 44 . By the above method, it is possible to form a mold 4 of concave diffraction gratings with spacings that are expanded equitably in the blaze direction.

9A and 9B are diagrams showing a method of manufacturing a concave diffraction grating mold according to Example 5 of another embodiment of the present invention. FIG. 9(b) shows the step of placing a concave substrate above the metal diffraction grating and a convex substrate below, FIG. 9(c) shows the bonding step, FIG. 9(d) shows the step of removing the concave substrate, e) is a diagram showing a step of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating.

In the step of forming the metal diffraction grating shown in FIG. 9( a ), sawtooth-shaped gratings having intervals that are expanded equidistantly in the blaze direction are formed on a flat metal substrate by semiconductor processes (photolithography and etching). A grating groove 51 is formed to form a metal diffraction grating 52 . In other words, the intervals between the grating grooves 51 of the metal diffraction grating 52 are increased stepwise along the blaze direction. Therefore, along the blaze direction, the metal diffraction grating 52 has a shape in which the spacing between adjacent grating grooves 51 gradually changes from narrow to wide. Here, by applying a semiconductor process (photolithography and etching), it is possible to manufacture the metal diffraction grating 52 in a short time compared to manufacturing the metal diffraction grating 52 by mechanical marking.

Next, in the step of placing a concave substrate above the metal diffraction grating and a convex substrate below the metal diffraction grating shown in FIG. , an adhesive layer 53 and a convex substrate 54 are placed on the surface opposite to the surface on which the grating grooves 51 are formed. That is, the concave surface of the concave substrate 55 is placed above the surface of the metal diffraction grating 52 on which the grating grooves 51 are formed, and the concave surface of the metal diffraction grating 52 on the side opposite to the surface of the metal diffraction grating 52 on which the grating grooves 51 are formed. The adhesive layer 53 is placed below the surface, and the convex surface of the convex substrate 54 is placed below the adhesive layer 53 so as to face each other.

In the bonding step shown in FIG. 9C, a temperature above the softening point of the bonding layer 53 and a load are applied in a vacuum atmosphere, and the surface of the metal diffraction grating 52 on which the grating grooves 51 are formed is placed on the concave substrate 55. In parallel with this, the metal diffraction grating 52 is adhered to the convex surface of the convex substrate 54 by the adhesive layer 53 .

Next, in the step of removing the concave substrate shown in FIG. 9D, the concave substrate 55 is removed (removed) after the adhesive layer 53 is cured by cooling while the load is applied. Subsequently, in the step of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating shown in FIG. A concave diffraction grating mold 5 is formed by removing a portion (an outer peripheral portion of the metal diffraction grating 52 that extends beyond the convex surface of the convex substrate 54).

As described above, according to this embodiment, the sawtooth-shaped lattice grooves 51 having intervals that are expanded equidistantly in the blaze direction are formed on a flat metal substrate by a semiconductor process (photolithography and etching). By forming the metal diffraction grating 52, it is possible to manufacture the metal diffraction grating 52 in a short time compared to manufacturing the metal diffraction grating 52 by mechanical engraving.

10A and 10B are diagrams showing a method of manufacturing a concave diffraction grating mold according to Embodiment 6 of another embodiment of the present invention. FIG. b) shows the step of laminating metal materials, FIG. 10(c) shows the step of forming a metal diffraction grating, and FIG. 10(d) shows a process of placing a concave substrate above and a convex substrate below the metal diffraction grating. 10(e) is the bonding step, FIG. 10(f) is the step of removing the concave substrate, and FIG. 10(g) is the mold of the concave diffraction grating by removing the outer periphery of the metal diffraction grating. It is a figure which shows the process of obtaining.

In the step of forming a planar diffraction grating shown in FIG. 10(a), grating grooves having a sawtooth shape are formed on a planar substrate by photolithography using a resist (resin) at an interval that is equally reduced in the blaze direction. 61a is formed to form the planar diffraction grating 60. FIG. In other words, the interval between the grating grooves 61a of the planar diffraction grating 60 is reduced stepwise along the blaze direction. Accordingly, along the blaze direction, the planar diffraction grating 60 has a shape in which the spacing between adjacent grating grooves 61a gradually changes from wide to narrow in steps.

Next, in the step of laminating a metal material shown in FIG. 10B, after forming a seed film on the surface on which the lattice grooves 61a are formed, a metal material is laminated by electroplating.
In the step of forming the metal diffraction grating shown in FIG. 10(c), the metal material is peeled off from the plane diffraction grating 60, and the metal material having sawtooth-shaped grating grooves 61b at intervals that are expanded equally in the blaze direction. A diffraction grating 62 is formed. In other words, the interval between the grating grooves 61b of the metal diffraction grating 62 is increased stepwise along the blaze direction. Accordingly, along the blaze direction, the metal diffraction grating 62 has a shape in which the spacing between adjacent grating grooves 61b gradually changes from narrow to wide in a stepwise manner. Here, the production of the plane diffraction grating 60 by photolithography can be made in a shorter time than that by machine stamping, and when the metal diffraction grating 62 is peeled off from the plane diffraction grating 60, the resist (resin) is removed. By dissolving, it can be easily peeled off.

Next, in the step of placing a concave substrate above the metal diffraction grating and a convex substrate below the metal diffraction grating shown in FIG. , an adhesive layer 63 and a convex substrate 64 are placed on the surface opposite to the surface on which the grating grooves 61b are formed. That is, the concave surface of the concave substrate 65 is placed above the surface of the metal diffraction grating 62 on which the grating grooves 61b are formed, and the concave surface of the metal diffraction grating 62 on the side opposite to the surface of the metal diffraction grating 62 on which the grating grooves 61b are formed. The adhesive layer 63 is placed below the surface, and the convex surface of the convex substrate 64 is placed below the adhesive layer 63 so as to face it.

In the bonding step shown in FIG. 10(e), a temperature higher than the softening point of the bonding layer 63 and a load are applied in a vacuum atmosphere, and the surface of the metal diffraction grating 62 on which the grating grooves 61b are formed is placed on the concave substrate 65. In parallel with this, the metal diffraction grating 62 is adhered to the convex surface of the convex substrate 64 with the adhesive layer 63 .

Next, in the step of removing the concave substrate shown in FIG. 10F, the concave substrate 65 is removed (removed) after the adhesive layer 63 is cured by cooling while the load is applied. Subsequently, in the process of obtaining a concave diffraction grating mold by removing the outer peripheral portion of the metal diffraction grating shown in FIG. A concave diffraction grating mold 6 is formed by removing the non-bonded outer peripheral portion (the outer peripheral portion of the metal diffraction grating 62 extending outside the convex surface of the convex substrate 64).

As described above, according to the present embodiment, the planar diffraction grating 60 is manufactured by photolithography, so that it can be manufactured in a shorter time than the mechanical stamping, and the metal diffraction grating 62 is separated from the planar diffraction grating 60. When the resist (resin) is dissolved, the resist (resin) can be easily removed.

In addition, the present invention is not limited to the above-described embodiments, and includes various modifications.
For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment.

Reference Signs List 1 Optical device 2 Concave diffraction grating 3, 4, 5, 6 Concave diffraction grating mold 11 Light source 12a, 12b Collecting lens 13 Sample chamber 14 Slit 16 Detector 21 Grating groove 22 Metal Layer 23 Resin layer 24 Concave substrate 30, 50, 60 Planar diffraction gratings 31, 41, 51, 61 Grating grooves 32, 42, 52, 62 Metal diffraction gratings 33, 43, 53, 63 Adhesive layer 34, 44, 54, 64... Convex substrates 35, 45, 55, 65... Concave substrates

Claims (5)

A concave diffraction grating that disperses and collects light,
It has sawtooth-shaped grating grooves on a concave substrate, the intervals between the sawtooth-shaped grating grooves are unequal, and the intervals between the grating grooves are equally reduced in the blaze direction. A concave diffraction grating characterized in that the reflection surface of the concave diffraction grating forms a part of a spherical surface. A concave diffraction grating that disperses and collects light,
Saw-tooth grating grooves are provided on a concave substrate, the intervals between the saw-tooth grating grooves are unequal, and the intervals between adjacent grating grooves change from wide to narrow along the blaze direction. and a concave diffraction grating characterized in that the reflecting surface of the concave diffraction grating forms a part of a spherical surface. In the concave diffraction grating according to claim 1 or claim 2,
A concave diffraction grating characterized in that the concave surface that disperses and converges light is a spherical surface. By photolithography and etching, or machining, a sawtooth shape is formed on a planar substrate, and unevenly spaced grating grooves having a shape in which the spacing of the grating grooves is reduced equidistantly in the blaze direction. forming to fabricate a planar diffraction grating substrate;
A concave substrate is installed so that the concave surface faces the surface on which the grating grooves are formed, and a convex substrate is installed via an adhesive layer so that the convex surface faces the surface opposite to the surface on which the grating grooves are formed. and
a bonding step of causing the surface of the planar diffraction grating substrate on which the grating grooves are formed to conform to the concave substrate, and bonding the planar diffraction grating substrate to the convex substrate with the adhesive layer;
After the concave substrate is removed, a step of removing an outer peripheral portion of the planar diffraction grating substrate extending outside the convex surface of the convex substrate to form a concave diffraction grating mold;
a step of transferring the mold of the concave diffraction grating having a shape in which the intervals of the grating grooves are equally reduced in the blaze direction and the reflection surface of the concave diffraction grating forming a part of a spherical surface, onto the surface of metal or resin; A method for manufacturing a concave diffraction grating, comprising: By photolithography and etching, or machining, a sawtooth shape is formed on a planar substrate, with unevenly spaced grating grooves, the spacing between adjacent grating grooves varying from wide to narrow along the blaze direction. fabricating a planar diffraction grating substrate by forming it to have a shape that gradually changes to the spacing;
A concave substrate is installed so that the concave surface faces the surface on which the grating grooves are formed, and a convex substrate is installed via an adhesive layer so that the convex surface faces the surface opposite to the surface on which the grating grooves are formed. and
a bonding step of causing the surface of the planar diffraction grating substrate on which the grating grooves are formed to conform to the concave substrate, and bonding the planar diffraction grating substrate to the convex substrate with the adhesive layer;
After the concave substrate is removed, a step of removing an outer peripheral portion of the planar diffraction grating substrate extending outside the convex surface of the convex substrate to form a concave diffraction grating mold;
The concave diffraction grating has a shape in which the intervals between grating grooves adjacent to each other gradually change in stages from wide intervals to narrow intervals along the blaze direction, and the reflecting surface of the concave diffraction grating forms a part of a spherical surface. A method of manufacturing a concave diffraction grating, characterized by comprising the step of transferring the mold of to a surface of metal or resin.

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