JP2004246193A - Blazed diffraction grating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a brightness changing pattern better than the blazed diffraction grating of the conventional technology and to make an observation region wider. <P>SOLUTION: The blazed diffraction grating has such light incident surfaces that make its longitudinal cross section shape into a saw tooth shape by being alternately and regularly arranged with long side sections and short side sections. The blazed diffraction grating is provided with one or a plurality of rectilinear recessed parts C on at least one slants A formed by the long side sections among the light incident surfaces. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a blazed diffraction grating, and more particularly, to a blazed diffraction grating for improving a luminance change pattern and widening an observation area.
[0002]
[Prior art]
As shown in FIG. 12, the general blazed diffraction grating 20 has a sawtooth-shaped vertical cross-sectional shape of a light incident surface 22 on which light enters, and a typical grating pitch _dy is approximately 0. The typical grating height h is about 0.1-1 μm. Then, the gentle slope A and the steep slope B are alternately and regularly arranged in a zigzag pattern so that the vertical cross-sectional shape becomes a saw blade shape.
[0003]
Such a blazed diffraction grating 20 is produced by a method using electron beam drawing or etching. In this case, the sloping surfaces A and B are made as flat as possible so that the blazed diffraction grating 20 can obtain a uniform diffraction efficiency over the whole.
[0004]
However, among the blazed diffraction gratings, by providing an uneven portion on the slope A, which is a long side portion having a large diffraction effect on the incident light λ, the brightness change pattern is improved as compared with the conventional blazed diffraction grating 20 and the observation area is improved. It was found that the area could be widened.
[0005]
That is, the present invention provides unevenness on a slope formed by a long side portion having a large diffraction effect on incident light, thereby improving the luminance change pattern and widening the observation area as compared with the related art. It is an object of the present invention to provide a blazed diffraction grating capable of performing the following.
[0006]
[Means for achieving the purpose]
In order to achieve the above object, the present invention takes the following measures.
[0007]
That is, the first aspect of the present invention provides a blazed diffraction grating having a light incidence surface such that a vertical cross section has a sawtooth shape by alternately arranging long sides and short sides. One or more linear concave portions or convex portions are provided on at least one slope formed by the long sides of the light incident surface.
[0008]
According to a second aspect of the present invention, in the blazed diffraction grating according to the first aspect of the present invention, a linear concave portion or a convex portion is formed on each of the light incident surfaces formed by the long side portions in the parallel direction of the grating lines. One or a plurality is provided so as to be substantially parallel to.
[0009]
According to a third aspect of the present invention, in the blazed diffraction grating according to the first aspect of the present invention, a linear concave portion or a convex portion is formed on each of the light incident surfaces formed by the long side portions in the parallel direction of the grating lines. One or a plurality are provided so as to be substantially orthogonal to.
[0010]
According to a fourth aspect of the present invention, in the blazed diffraction grating according to any one of the first to third aspects, when three or more concave portions or convex portions are provided on each surface, a plurality of concave portions or convex portions are provided on each surface. Are provided at substantially equal pitches.
[0011]
According to a fifth aspect of the present invention, in the blazed diffraction grating according to any one of the first to third aspects, when three or more concave portions or convex portions are provided on each surface, a plurality of concave portions or convex portions are provided on each surface. Are provided at different pitches.
[0012]
According to a sixth aspect of the present invention, in the blazed diffraction grating according to the fourth or fifth aspect, the plurality of concave portions or convex portions have substantially the same shape and size.
[0013]
According to a seventh aspect of the present invention, in the blazed diffraction grating according to the fourth or fifth aspect of the present invention, at least one of the plurality of concave portions or convex portions has a shape or size different from the others. At least one is provided.
[0014]
Therefore, in the blazed diffraction grating provided with the above-described means, as shown in the following (1) to (4), it is possible to achieve the function and effect which cannot be achieved by the conventional blazed diffraction grating.
[0015]
(1) A part of the diffracted light diffracted on the slope formed by the long sides can be emitted in another direction. As a result, when observing from a specific observation region, a pattern having a luminance change can be perceived.
[0016]
(2) The observation area can be expanded.
[0017]
(3) A part of the diffracted light can be converted into scattered light, and whitened emission light can be obtained.
[0018]
(4) It is no longer practically feasible to imitate with the fabrication process applied to fabricate blazed diffraction gratings of the prior art. As a result, it is not created by an unauthorized third party.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
Note that the same reference numerals in the drawings used in the description of each embodiment below denote the same parts as in FIG. 12.
[0021]
(First Embodiment)
A first embodiment will be described with reference to FIGS.
[0022]
FIG. 1 is a perspective view showing a configuration example of a light incident surface of the blazed diffraction grating according to the first embodiment, in which each inclined surface A is provided with two concave portions C.
[0023]
FIG. 2 is also a perspective view showing a configuration example of a light incident surface of the blazed diffraction grating according to the first embodiment, in which each slope A is provided with three or more recesses C, and the recesses C are arranged at equal pitches. It is a configuration that is arranged.
[0024]
FIG. 3 is a perspective view showing a modified configuration example of the light incidence surface of the blazed diffraction grating according to the first embodiment, in which a plurality of convex portions D are provided on each slope A, and the convex portions D are arranged at equal pitches. It is a configuration arranged in.
[0025]
That is, the blazed diffraction grating according to the present embodiment includes the concave portion C or the convex portion D that extends linearly in the grating pitch direction (zigzag direction) on the slope A.
[0026]
In the blazed diffraction grating 10 as shown in FIG. 1, as an example, a configuration in which two concave portions C are provided on each slope A is shown. However, one concave portion C is provided on each slope A, or As shown in FIG. 2, a configuration in which three or more units are provided may be used. Further, a different number of concave portions C may be provided for each slope A.
[0027]
When three or more recesses C are provided on each slope A, the recesses C provided on the same slope A are arranged at the same pitch d as in a blazed diffraction grating 11 as shown in FIG. It is constituted by doing.
[0028]
Further, a convex portion D may be provided instead of the concave portion C. A blazed diffraction grating 12 as shown in FIG. 3 shows an example of a configuration having a convex portion D instead of the concave portion C shown in FIG. It is desirable that the width w of the concave portion C and the convex portion D be several μm or less in order to sufficiently obtain a light scattering effect or a light diffraction effect, which is a general grating pitch d _y (0) of the blazed diffraction grating 20. 0.5 to 1 μm), which is sufficiently small, so that processing is not difficult. Further, as shown in FIGS. 4A, 4B, and 4C, the cross-sectional shape of the concave portion C is desirably a semicircular, triangular, or quadrangular shape. It is desirable that the cross-sectional shape of the convex portion D is also a semicircular, triangular, or quadrangular shape as shown in FIGS. 4D, 4E, and 4F.
[0029]
The cross-sectional shape as shown in FIG. 4 also does not involve difficulty in processing. However, since it is extremely complicated to reproduce the shape, size, number, arrangement direction, and the like of the concave portions C or the convex portions D, the manufacturing process applied to the manufacture of the blazed diffraction grating of the related art is difficult. It is not easy, and it is extremely difficult for a third party who does not provide such information to make it.
[0030]
Next, the operation of the blazed diffraction grating according to the present embodiment configured as described above will be described.
[0031]
As shown in FIG. 12, the long sides forming the slope A and the short sides forming the slope B are alternately and regularly arranged in a zigzag pattern, so that the vertical cross section has a saw blade shape. In a blazed diffraction grating having a light incident surface such that the incident light λ can be emitted in a specific direction by the inclined surface A as diffracted light. At the same time, the generation of diffracted light by the slope B can be kept low.
[0032]
The blazed diffraction grating according to the present embodiment has a linear concave portion C or a convex portion D on the slope A of the blazed diffraction grating 20 of the related art having such an action, for example, as shown in FIGS. One or more.
[0033]
With such a configuration, the diffracted light on the slope A is scattered not in one specific direction but in an arbitrary direction. In particular, as shown in FIGS. 2 and 3, when a plurality of concave portions C and convex portions D are discretely present, local directional scattering of light is obtained in the concave portions C and convex portions D.
[0034]
The degree of the scattering depends on parameters including the arrangement direction, arrangement location, number, shape and size of the concave portions C or the convex portions D, and the pitch between adjacent concave portions C or the convex portions D. Therefore, by appropriately adjusting the values of these parameters, the diffracted light can be distributed in a predetermined direction, and an effect that cannot be achieved with the blazed diffraction grating 20 of the related art can be obtained.
[0035]
For example, in the blazed diffraction grating 20 according to the related art, the diffracted light was seen in a uniform direction because the diffracted light was obtained only in a certain direction. Since it is possible to change the pattern, a pattern having a change in luminance can be realized. In particular, as shown in FIGS. 2 and 3, a specific light scattering effect is realized on the surface of the blazed diffraction grating by arranging such that the pitch d between adjacent concave portions C or convex portions D is constant. It becomes possible.
[0036]
For example, a linear recess C or protrusions D, by parallel to the direction (zigzag direction) of the grating pitch d _y blazed diffraction grating, when observing the diffracted light by the slope A, the left-right direction (grating it is possible to obtain a light scattered in a direction) perpendicular to the direction of the pitch d _y, it is possible to widen the viewing area in the lateral direction.
[0037]
Further, by reducing the adjacent pitch d between the concave portion C and the convex portion D, incident light is efficiently scattered, and it becomes possible to observe whitish emitted light.
[0038]
In the present embodiment, as shown in FIGS. 1 to 3, a configuration is shown in which either the concave portion C or the convex portion D is selectively disposed on the slope A, but as described above. The function and effect are not limited to such a configuration, and the same effect can be achieved even in a configuration in which both the concave portion C and the convex portion D are arranged on the slope A.
[0039]
Further, as shown in the vertical sectional views of FIGS. 5A and 5B, the cross-sectional shape of the concave portion C and the convex portion D may be processed into a blazed shape. With such a configuration, it is possible to further vary the light emission direction.
[0040]
(Second embodiment)
The second embodiment will be described with reference to FIGS.
[0041]
FIG. 6 is a perspective view illustrating a configuration example of a light incident surface of a blazed diffraction grating according to the second embodiment, in which a plurality of concave portions C are provided on each slope A, and a pitch d between adjacent concave portions C is smaller. The arrangements are different (d ₁ ≠ d ₂ ≠ d ₃ ≠ d ₄ ≠ d ₅ ).
[0042]
FIG. 7 is a perspective view showing a modified configuration example of the light incidence surface of the blazed diffraction grating according to the second embodiment, in which each slope A has a plurality of protrusions D, and the adjacent protrusions D are adjacent to each other. The arrangement is such that the pitches d are different from each other (d ₁ ≠ d ₂ ≠ d ₃ ≠ d ₄ ).
[0043]
That is, the blazed diffraction grating according to the present embodiment is provided with three or more concave portions C or convex portions D linearly extending in the grating pitch direction on the inclined surface A, and three or more concave portions C or convex portions D on each inclined surface A. The provided concave portion C or convex portion D has a different pitch from the adjacent concave portion C or convex portion D, respectively.
[0044]
The blazed diffraction grating 13 as shown in FIG. 6 shows an example in which the concave portions C provided on the same slope A are arranged so that the pitches between adjacent concave portions C are different.
[0045]
In either case of FIGS. 6 and 7, the adjacent pitches d need not all be different, and it is sufficient if there is at least one portion having a pitch different from the others. The blazed diffraction grating 14 as shown in FIG. 7 shows an example in which the protrusions D provided on the same slope A are arranged so that the pitches between the protrusions D and the adjacent protrusions D are different.
[0046]
The concave portion C and the convex portion D are desirably several μm or less in order to sufficiently obtain a light scattering effect or a light diffraction effect, which is a general grating pitch d _y (0.5 to 0.5 μm) of the blazed diffraction grating 20. Processing is not difficult because it is sufficiently smaller than 1 μm). Further, as shown in FIGS. 4A, 4B, and 4C, the cross-sectional shape of the concave portion C is desirably a semicircular, triangular, or quadrangular shape. It is desirable that the cross-sectional shape of the convex portion D is also a semicircular, triangular, or quadrangular shape as shown in FIGS. 4D, 4E, and 4F.
[0047]
Such a cross-sectional shape also does not involve difficulties in processing. However, since it is extremely complicated to reproduce the shape, size, number, arrangement direction, and the like of the concave portions C or the convex portions D, the manufacturing process applied to the manufacture of the blazed diffraction grating of the related art is difficult. It is not easy, and it is extremely difficult for a third party who does not provide such information to make it.
[0048]
Next, the operation of the blazed diffraction grating according to the present embodiment configured as described above will be described.
[0049]
A blazed diffraction grating according to the present embodiment is formed on a slope A of a blazed diffraction grating 20 of the prior art as shown in FIG. 12 by, for example, a linear concave portion C or a convex portion D as shown in FIGS. And three or more pitches between adjacent concave portions C or convex portions D and at least one portion different from the other pitches.
[0050]
With such a configuration, the diffracted light on the slope A is scattered not in one specific direction but in an arbitrary direction, and local directional scattering of light is obtained in each of the concave portion C and the convex portion D.
[0051]
As described in the first embodiment, the degree of the scattering includes the arrangement direction, arrangement location, number, shape and size of the concave portions C or the convex portions D, and the pitch between the adjacent concave portions C or the convex portions D. Depends on parameters. In the present embodiment, among the pitches of the adjacent concave portions C and convex portions D, the configuration is such that there is at least one portion different from the other pitches. Light scattering different from that of other parts is realized.
[0052]
Therefore, by appropriately adjusting the values of these parameters, the diffracted light can be distributed in a predetermined direction, and it is possible to obtain operational effects that cannot be achieved with the blazed diffraction grating 20 according to the related art. .
[0053]
For example, in the blazed diffraction grating 20 according to the related art, since the diffracted light was obtained only in a fixed direction, it appeared to shine uniformly. However, in the blazed diffraction grating according to the present embodiment, the light amount of the diffracted light was partially reduced. Since it is possible to change the pattern, a pattern having a change in luminance can be realized. In this embodiment, in addition, by changing the pitch of each of the concave portions C or the convex portions D, it becomes possible to obtain different light scattering.
[0054]
Also, the linear recess C or protrusions D, since the parallel to the pitch direction d _y blazed diffraction grating, as in the first embodiment, when observing the diffracted light from the inclined surface A , it is possible to obtain a light scattered in the lateral direction (direction perpendicular to the pitch direction d _y), it is possible to widen the viewing area in the lateral direction.
[0055]
In the present embodiment, as shown in FIGS. 6 and 7, a configuration is shown in which either the concave portion C or the convex portion D is selectively disposed on the slope A, but as described above. The function and effect are not limited to such a configuration, and the same effect can be achieved even in a configuration in which both the concave portion C and the convex portion D are arranged on the slope A.
[0056]
Further, as shown in the vertical sectional views of FIGS. 5A and 5B, the cross-sectional shape of the concave portion C and the convex portion D may be processed into a blazed shape. With such a configuration, it is possible to further vary the light emission direction.
[0057]
(Third embodiment)
A third embodiment will be described with reference to FIGS.
[0058]
FIG. 8 is a perspective view showing a configuration example of a light incidence surface of a blazed diffraction grating according to the third embodiment, in which each slope A is provided with three recesses C, and adjacent recesses C are arranged at equal pitches. It is a configuration arranged in.
[0059]
FIG. 9 is also a perspective view showing a configuration example of a light incident surface of a blazed diffraction grating according to the third embodiment, in which each slope A has three convex portions D, and adjacent convex portions D are connected to each other. This is a configuration in which they are arranged at an equal pitch.
[0060]
That is, the blazed diffraction grating according to the present embodiment has three concave portions C or convex portions D linearly extending on the inclined surface A so as to be substantially orthogonal to the grating pitch direction (zigzag direction). The concave portions C or the convex portions D provided on the same slope A are provided at the same pitch d with the adjacent concave portion C or the convex portion D, respectively.
[0061]
The blazed diffraction grating 15 shown in FIG. 8 shows an example in which the concave portions C provided on the same slope A are arranged so that the pitch d between the concave portions C adjacent to each other is equal.
[0062]
The blazed diffraction grating 16 shown in FIG. 9 shows an example in which the protrusions D provided on the same slope A are arranged so that the pitch d between the adjacent protrusions D is equal.
[0063]
It is desirable that the width w of the portion C and the convex portion D is several μm or less in order to sufficiently obtain a light scattering effect or a light diffraction effect, which is the general grating pitch _dy (0) of the blazed diffraction grating 20. 0.5 to 1 μm), which is sufficiently small, so that processing is not difficult. Further, as shown in FIG. 4, it is desirable that the cross-sectional shape of the concave portion C and the convex portion D is a semicircular, triangular, or quadrangular shape. Such a cross-sectional shape also does not involve difficulties in processing. However, since it is extremely complicated to reproduce the shape, size, number, arrangement direction, and the like of the concave portions C or the convex portions D, the manufacturing process applied to the manufacture of the blazed diffraction grating of the related art is difficult. It is not easy, and it is extremely difficult for a third party who does not provide such information to make it.
[0064]
Since the blazed diffraction grating according to the present embodiment is configured as described above, the same operation and effect as those of the first embodiment can be obtained. However, since the extending direction of the concave portion C and the convex portion D is set to be substantially perpendicular to the case of the first embodiment, when observing the diffracted light by the slope A, the grating pitch d it is possible to obtain a light scattered in the direction of _y, the observation area can be widened in the direction of the grating pitch d _y.
[0065]
(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS.
[0066]
FIG. 10 is a perspective view showing a configuration example of the light incident surface of the blazed diffraction grating according to the fourth embodiment, in which each slope A is provided with three recesses C, and the pitch between adjacent recesses C is smaller. The configurations are arranged so as to be different (d ₁ ≠ d ₂ ).
[0067]
FIG. 11 is also a perspective view showing a configuration example of a light incident surface of the blazed diffraction grating according to the fourth embodiment, in which each slope A is provided with three convex portions D and adjacent convex portions D are adjacent to each other. The configuration is such that the pitches are different (d ₁ ≠ d ₂ ).
[0068]
That is, the blazed diffraction grating according to the present embodiment includes three or more concave portions C or convex portions D linearly extending on the slope A so as to be substantially orthogonal to the grating pitch direction, on each slope A. The concave portion C or the convex portion D provided on the same slope A has a different pitch from the adjacent concave portion C or the convex portion D, respectively.
[0069]
The blazed diffraction grating 17 as shown in FIG. 10 shows an example in which the concave portions C provided on the same slope A are arranged so that the pitch between the concave portions C adjacent to each other is different.
[0070]
The blazed diffraction grating 18 as shown in FIG. 11 shows an example in which the convex portions D provided on the same slope A are arranged so that the pitch between the convex portions D adjacent to each other is different.
[0071]
In both cases of FIGS. 10 and 11, it is not necessary for all adjacent pitches to be different, and it is sufficient that at least one portion has a pitch different from the others.
[0072]
The concave portion C and the convex portion D are desirably several μm or less in order to sufficiently obtain a light scattering effect or a light diffraction effect, which is a general grating pitch d _y (0.5 to 0.5 μm) of the blazed diffraction grating 20. Processing is not difficult because it is sufficiently smaller than 1 μm). Further, as shown in FIG. 4, it is desirable that the cross-sectional shape of the concave portion C and the convex portion D is a semicircular, triangular, or quadrangular shape. Such a cross-sectional shape also does not involve difficulties in processing. However, since it is extremely complicated to reproduce the shape, size, number, arrangement direction, and the like of the concave portions C or the convex portions D, the manufacturing process applied to the manufacture of the blazed diffraction grating of the related art is difficult. It is not easy, and it is extremely difficult for a third party who does not provide such information to make it.
[0073]
Since the blazed diffraction grating according to the present embodiment is configured as described above, the same operation and effect as those of the second embodiment can be obtained. However, since the extending direction of the concave portion C and the convex portion D is set to be substantially perpendicular to the case of the first embodiment, when observing the diffracted light by the slope A, the grating pitch d it is possible to obtain a light scattered in the direction of _y, the observation area can be widened in the direction of the grating pitch d _y.
[0074]
Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to such configurations. Within the scope of the technical idea described in the claims, those skilled in the art can come up with various modified examples and modified examples, and these modified examples and modified examples are also within the technical scope of the present invention. It is understood that it belongs to. For example, in each of the above embodiments, the effect has been described with respect to the reflection type blazed diffraction grating. However, the above-described operation and effect can be obtained not only in the case of the reflection type blazed grating but also in the case of the transmission type blazed diffraction grating. Even if it is, it can be performed similarly.
[0075]
【The invention's effect】
With the configuration described above, the blazed diffraction grating according to the present invention can achieve the following effects.
[0076]
(1) By forming linear fine concave / convex portions on the gentle slope of the blazed diffraction grating, a part of the diffracted light can be emitted in another direction, and when observed from a specific observation region. A pattern having a luminance change can be realized.
[0077]
(2) By providing fine linear concave / convex portions on the gentle slope of the blazed diffraction grating, a part of the diffracted light can be emitted in another direction, and the observation area can be expanded.
[0078]
(3) By forming fine linear concave / convex portions on the gentle slope of the blazed diffraction grating, a part of the diffracted light can be converted to scattered light, and a whitish emission light can be obtained. Can be.
[0079]
(4) By providing a configuration in which fine concave / convex portions are provided on a gentle slope of the blazed diffraction grating with predetermined specifications, it is impossible to imitate the blazed diffraction grating only by a normal blazed diffraction grating manufacturing process.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration example of a light incident surface of a blazed diffraction grating according to a first embodiment (when each slope A has two concave portions);
FIG. 2 is a perspective view showing a configuration example of a light incident surface of the blazed diffraction grating according to the first embodiment (when three or more concave portions are provided at equal pitches on each slope A).
FIG. 3 is a perspective view showing a modified configuration example of a light incident surface of the blazed diffraction grating according to the first embodiment (when three or more convex portions are provided at equal pitches on each slope A).
FIG. 4 is a cross-sectional view illustrating an example of a cross-sectional shape of a concave portion and a convex portion. FIG. 5 is a schematic diagram illustrating an example of a concave portion and a convex portion processed with a blazed shape. FIG. 6 is a blazed diffraction according to a second embodiment. Perspective view showing a configuration example of the light incident surface of the grating (when each slope A is provided with three or more recesses at different pitches)
FIG. 7 is a perspective view showing a configuration example of a light incident surface of a blazed diffraction grating according to a second embodiment (when three or more convex portions are provided on each slope A at different pitches).
FIG. 8 is a perspective view showing a configuration example of a light incidence surface of a blazed diffraction grating according to a third embodiment (when three or more concave portions are provided at equal pitches on each slope A).
FIG. 9 is a perspective view showing a configuration example of a light incidence surface of a blazed diffraction grating according to a third embodiment (when three or more convex portions are provided at equal pitches on each slope A).
FIG. 10 is a perspective view showing a configuration example of a light incident surface of a blazed diffraction grating according to a fourth embodiment (when three or more concave portions are provided on each slope A at different pitches).
FIG. 11 is a perspective view showing a configuration example of a light incident surface of a blazed diffraction grating according to a fourth embodiment (when three or more projections are provided at different pitches on each slope A).
FIG. 12 is a cross-sectional structural view of a blazed diffraction grating according to the related art.
_dy : grating pitch, A, B: slope, C: concave, D: convex, λ: incident light, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 20: blazed diffraction grating 22 ... Light incident surface

Claims (7)

In the blazed diffraction grating having a light incident surface such that the vertical cross-sectional shape becomes a saw-tooth shape by the long side portion and the short side portion being arranged alternately and regularly,
A blazed diffraction grating comprising one or more linear concave portions or convex portions on at least one surface of the light incident surface formed by the long side portion. The blazed diffraction grating according to claim 1,
Blazed diffraction provided with one or more linear concave portions or convex portions on each of the light incident surfaces formed by the long side portions so as to be substantially parallel to the parallel direction of the lattice lines. lattice. The blazed diffraction grating according to claim 1,
A blazed diffraction grating provided with one or more linear concave portions or convex portions on each of the light incident surfaces formed by the long side portions so as to be substantially orthogonal to the parallel direction of the grid lines. . The blazed diffraction grating according to any one of claims 1 to 3,
In the case where three or more concave portions or convex portions are provided on each surface, a blazed diffraction grating including a plurality of concave portions or convex portions on each surface at substantially equal pitches. The blazed diffraction grating according to any one of claims 1 to 3,
In the case where three or more concave portions or convex portions are provided on each surface, a blazed diffraction grating including a plurality of concave portions or convex portions at different pitches on each surface. The blazed diffraction grating according to claim 4 or 5,
A blazed diffraction grating in which the plurality of concave portions or convex portions have substantially the same shape and size. The blazed diffraction grating according to claim 4 or 5,
A blazed diffraction grating comprising at least one concave or convex portion having at least one of a shape and a dimension different from the others among the plurality of concave portions or convex portions.

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