JP2004271588A - Brazed diffraction grating, display body using brazed diffraction grating, and optical sheet using brazed diffraction grating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a brazed diffraction grating which has high diffraction efficiency and high moldability in duplication and can stably be duplicated. <P>SOLUTION: In the brazed diffraction grating 2 in which the sectional shape of an elevation of a light incidence surface 4 is a saw-tooth shape, the saw-tooth shape is formed by alternately arranging an optical operation surface L whose sectional shape is formed of a straight line so that incident light A incident on the light incidence surface 4 optically operates and a non-optical operation surface M whose sectional shape is formed of a curved light so that the incident light A does not optically operate. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a blazed diffraction grating, a display using the blazed diffraction grating, and an optical sheet using the blazed diffraction grating.
[0002]
[Prior art]
As shown in FIG. 7, the general shape of the blazed diffraction grating 20 is such that the vertical cross-sectional shape of the surface of the light incident surface 22 on which the incident light is incident has a saw blade shape. Typical lattice spacing _{d y} is about approximately 0.5 to 1 [mu] m, the height h of the exemplary grating is about 0.1 to 1 [mu] m. In particular, the optimum grating height h mainly depends on the refractive index of the material constituting the blazed diffraction grating 20 and whether it is a reflection type or a transmission type.
[0003]
If the y-direction indicating the direction of the lattice vector in FIG. 7, the lattice spacing d _y of blazed diffraction grating 20 is determined by the following equation. Here, it is assumed that the surface of the light incident surface 22 is in contact with air.
[0004]
d _y = λ / (sin α−sin β) (1)
Here, λ is the wavelength of the incident light, α is the exit angle of the zero-order diffracted light (transmitted light or specularly reflected light) in the y direction, and β is the exit angle of the first-order diffracted light in the y direction.
[0005]
The most common condition, when light in a direction perpendicular to the substrate to consider the condition of injection, is an exit angle beta = 0 ° of a first order diffracted light in the y-direction, 0 and the angle alpha = alpha _N-order diffracted light Then, the above equation (1) is simplified as follows.
[0006]
d _y = λ / sinα _N (2)
In order to maximize the diffraction efficiency of the blazed diffraction grating, that is, the diffraction ratio of the first-order diffracted light to the incident light, the angle φ of the slope of the saw blade is designed so as to satisfy the following expression (3). .
[0007]
φ = α _N / 2 (3)
[0008]
[Problems to be solved by the invention]
However, such a conventional blazed diffraction grating has the following problems.
[0009]
That is, in order to duplicate the conventional blazed diffraction grating as described above, in addition to injection molding, many techniques such as embossing on a thermoplastic resin or a UV-curable resin have been put to practical use.
[0010]
However, as shown in FIG. 8, in the process of duplicating the blazed diffraction grating, when the molding material 26 which is the material of the duplicate is poured into the original plate such as the mold 24, the microstructure is accurately formed without gaps. Must be poured. Also, when peeling in the direction indicated by the arrow in the figure after molding, the object to be molded 26 must be peeled without being broken or distorted.
[0011]
In the duplication process, if the duplicate does not accurately reproduce the original plate and has minute defects, the diffraction efficiency is reduced, noise (unnecessary light components) is generated, and the performance is reduced. Problem.
[0012]
The present invention has been made in view of such circumstances, and a first object of the present invention is to provide a blazed diffraction grating having high diffraction efficiency, high moldability at the time of duplication, and capable of stably duplicating. Is to provide.
[0013]
Further, a second object is to provide an optical sheet having excellent diffraction efficiency and excellent moldability by forming such a blazed diffraction grating on the sheet surface.
[0014]
Further, a third object is to provide a display body which is excellent in moldability and is brightly displayed by forming such a blazed diffraction grating in a cell and displaying an image using the cell as a pixel. is there.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following measures.
[0016]
That is, according to the first aspect of the present invention, in order to achieve the first object, in a blazed diffraction grating in which a vertical cross-sectional shape of a light incident surface is a saw blade shape, incident light incident on the light incident surface is optically reflected. An optical action surface having a straight sectional shape formed so as to operate and a non-optical working surface having a curved vertical sectional shape so that incident light does not act optically are alternately arranged on the light incident surface. This forms a saw blade shape whose vertical cross-sectional shape is composed of straight lines and curved lines.
[0017]
Therefore, in the blazed diffraction grating according to the first aspect of the present invention, by taking the above-described means, it is possible to achieve high diffraction efficiency, high moldability at the time of replication, and stable replication.
[0018]
According to a second aspect of the present invention, in order to achieve the first object, in a blazed diffraction grating in which a vertical cross-sectional shape of a light incident surface has a saw blade shape, incident light incident on the light incident surface acts optically. And the first boundary where the inclination of the optically active surface whose vertical cross-sectional shape is formed by a straight line and the inclination of the non-optically active surface whose vertical cross-sectional shape is formed by a curve so that incident light does not act optically coincide with each other. A second boundary where the inclination of the non-optical operation surface and the inclination of the optical operation surface do not coincide with each other is alternately arranged on the light incident surface, and the optical operation surface and the non-optical operation surface are connected to each other at each boundary. Form a blade shape.
[0019]
Therefore, in the blazed diffraction grating according to the second aspect of the present invention, by taking the above measures, it is possible to have high diffraction efficiency, high moldability at the time of duplication, and to stably duplicate.
[0020]
According to a third aspect of the present invention, there is provided a blazed diffraction grating according to the first or second aspect of the present invention, wherein the curvature radius of a curve forming the non-optically active surface is reduced by light incidence. 10% or more and 80% or less of the arrangement pitch of the optical action surface on the surface.
[0021]
Therefore, in the blazed diffraction grating according to the third aspect of the present invention, by taking the above means, it is possible to have high diffraction efficiency, high moldability at the time of replication, and stable replication.
[0022]
According to a fourth aspect of the present invention, in order to achieve the first object, in a blazed diffraction grating in which a vertical cross-sectional shape of a light incident surface has a saw blade shape, incident light incident on the light incident surface acts optically. In this way, an optically active surface with a vertical cross-sectional shape formed by a straight line and a non-optically active surface formed by combining a plurality of straight lines with a vertical cross-sectional shape so that incident light does not act optically are alternated on the light incident surface. To form a saw blade shape.
[0023]
Therefore, in the blazed diffraction grating according to the fourth aspect of the present invention, by taking the above measures, it is possible to have high diffraction efficiency, high moldability at the time of duplication, and stable duplication.
[0024]
According to a fifth aspect of the present invention, in order to achieve the second object, the blazed diffraction grating according to any one of the first to fourth aspects is arranged on a sheet surface.
[0025]
Therefore, in the optical sheet according to the fifth aspect, by forming the blazed diffraction grating according to any one of the first to fourth aspects on the sheet surface, both the diffraction efficiency and the moldability are improved. Can be.
[0026]
According to a sixth aspect of the present invention, in order to achieve the third object, the blazed diffraction grating according to any one of the first to fourth aspects is arranged in each of a plurality of cells. For each blazed diffraction grating, the spatial frequency, which is the reciprocal of the arrangement pitch of the optical working surface arranged on the light incident surface, the angle of inclination of the optical working surface with respect to the light incident surface, and the incident light on the optical working surface By setting the diffraction efficiency to a predetermined value, an image in which each cell is a pixel is displayed.
[0027]
Therefore, in the display according to the sixth aspect of the present invention, by taking the above measures, the blazed diffraction grating according to any one of the first to fourth aspects of the present invention is formed in the cell, and the cell is formed of a pixel. By displaying an image that has been set, it is possible to display the image excellent in moldability and bright.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
Note that the same reference numerals in the drawings used for describing the following embodiments denote the same parts as in FIGS. 7 and 8.
[0030]
(First Embodiment)
A first embodiment will be described with reference to FIGS.
[0031]
FIG. 1 is a perspective view showing an example of the blazed diffraction grating according to the first embodiment.
[0032]
FIG. 2 is an elevational sectional view showing the vicinity of the surface of the blazed diffraction grating according to the first embodiment.
[0033]
That is, in the blazed diffraction grating 2 according to the present embodiment, the vertical cross-sectional shape of the light incident surface 4 has a saw blade shape. Then, as shown in the vertical sectional view of FIG. 2, an optical function in which a vertical sectional shape is formed as a straight line so that the incident light A incident on the light incident surface 4 at an incident angle θ performs an optical function such as reflection or transmission. The sawtooth shape is formed by alternately arranging the surface L and the non-optically active surface M having a curved vertical cross-sectional shape so that the incident light A does not optically act on the light incident surface 4. Further, the curvature radius R of the curve forming the non-optical surfaces M, is set to 10% to 80% of the lattice spacing d _y in the light incidence surface 4.
[0034]
With such a configuration, the non-optically active surface M is invisible from the incident light A incident from the upper left in FIG. 2, so that the incident light A does not enter and the optical action such as reflection and transmission is not performed. Does not happen.
[0035]
The boundary between the optically active surface L and the non-optically active surface M includes a boundary B1 near the lowermost position of the saw blade and a boundary B2 that forms the vertex of the saw blade. At the boundary B1, the inclination of the non-optical operation surface M and the inclination of the optical operation surface L match. That is, the non-optical working surface M and the optical working surface L are smoothly connected. On the other hand, at the boundary B2, the inclination of the non-optically active surface M and the inclination of the optically active surface L do not coincide with each other, and form the apex of the saw blade.
[0036]
The blazed diffraction grating 2 having such a configuration has an extremely high diffraction efficiency with respect to the incident light A, which is close to 100% at the maximum. That is, most of the incident light A is reflected on the optically active surface L, and becomes a diffracted light D as shown in FIG. Further, the moldability at the time of duplication is extremely high, and stable duplication is enabled.
[0037]
In particular, since the optically active surface L and the non-optically active surface M are smoothly connected at the boundary B1, the number of portions where sharp portions need to be accurately formed is reduced, and the formability of the optically active surface L is extremely low. high. In the case of the blazed diffraction grating of the prior art, there is a phenomenon that the valleys of the original plate are liable to cause molding defects, particularly depending on the molding method. However, the blazed diffraction grating 2 according to the present embodiment employs such a molding method. High moldability can be obtained, and a good duplicate can be obtained. In particular, when the curvature radius R of the non-optically active surface M is 0.1 μm or more, moldability and molding stability are high.
[0038]
Since the blazed diffraction grating 2 according to the present embodiment has the above-described configuration, it is possible to realize an extremely high diffraction efficiency of the incident light A, which is close to 100% at the maximum. In addition, the moldability during replication is extremely high, and stable replication is possible.
[0039]
In the above embodiment, the case where the incident light A is obliquely incident and the diffracted light D is emitted vertically as shown in FIG. 2 has been described. In this case, since the incident light A is emitted as the diffracted light D without being blocked at all, the diffraction efficiency, which is the light use efficiency for the incident light A, becomes the highest. Even when the incident light A is incident at an angle other than the incident angle θ as shown in FIG. 2, or when the diffracted light D is emitted in a direction other than the vertical direction, high diffraction efficiency and high High moldability can be realized.
[0040]
In addition, the blazed diffraction grating 2 according to the present embodiment can be applied not only to the reflection type that reflects the incident light A as shown in FIG. In the case of the reflection type, by providing a reflection layer of aluminum, silver, or the like on the molding surface, the reflectance can be increased, and the intensity of the diffracted light can be improved. At this time, the light incident surface may be a molding surface or a reflection layer surface.
[0041]
As shown in FIG. 3, the blazed diffraction grating 2 according to the present embodiment can be molded as an object 26 obtained by using a mold 24 having a valley having a curved cross-sectional shape. However, the present invention is not limited to this, and molding can be performed by using a mold having sharp valleys and curved ridges so as to be suitable for the molding method.
[0042]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG.
[0043]
FIG. 4 is an elevational sectional view showing the vicinity of the surface of the blazed diffraction grating according to the second embodiment. The same parts as those in FIG. Is described only.
[0044]
That is, the blazed diffraction grating 6 according to the present embodiment is formed by combining the non-optically active surface M shown in FIG. 2 with a plurality of non-optically active surfaces having a straight vertical sectional shape. In the example shown in FIG. 4, the non-optically active surface M1 and the non-optically active surface M2 are combined to correspond to the non-optically active surface M shown in FIG.
[0045]
The non-optically active surface M1 is connected to the optically active surface L at the boundary B5 and the non-optically active surface M2 at the boundary B3 by setting the inclination angle w with respect to the substrate normal to be smaller than the incident angle θ of the incident light A. are doing. The non-optically active surface M2 is a surface parallel to the base material, and is connected to the non-optically active surface M1 at the boundary B3 and to the optically active surface L at the boundary B4. The length of the non-optically active surface M2 is set so that the incident light A passing through the vicinity of the boundary B5 does not enter the non-optically active surface M2. This prevents any incident light A from being incident on the non-optically active surfaces M1 and M2.
[0046]
Even with the blazed diffraction grating 6 having the above-described configuration, the same operation and effect as those of the blazed diffraction grating 2 according to the first embodiment can be achieved.
[0047]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS.
[0048]
Here, a display body and an optical sheet using the blazed diffraction grating according to the first and second embodiments will be described.
[0049]
FIG. 5 is a conceptual diagram showing an example of a display using the blazed diffraction grating according to the first and second embodiments. FIG. 6 is a conceptual diagram showing an example of an optical sheet using the blazed diffraction grating according to the first and second embodiments.
[0050]
That is, in the display according to the present embodiment, the blazed diffraction gratings according to the first and second embodiments are arranged in each cell 10 as shown in FIG. 5B. Then, as shown in FIG. 5 (c), each blazed diffraction grating arranged in each cell 10, the spatial frequency is the inverse of the lattice spacing d _y optical surfaces L in the light incident surface, the optical against the light incident surface The inclination angle φ of the working surface L and the diffraction efficiency of the incident light on the optical working surface L are set to predetermined values. In this way, as shown in FIG. 5A, a display body 12 that displays an image using each cell 10 as a pixel is configured.
[0051]
The display body 12 configured as described above is observed very brightly and can be stably molded with high precision even in the molding process. At this time, the spatial frequency of the blazed diffraction grating arranged in the cell 10 is mainly the observed color (wavelength), the inclination angle φ of the optical working surface L is the observation direction, the diffraction efficiency and the area of the cell 10 are the observed brightness. Characterize. Therefore, by correctly designing and setting these parameters, a full-color image or an image having parallax is displayed.
[0052]
Further, as shown in FIG. 6A, by arranging the blazed diffraction gratings according to the first and second embodiments on the surface of the optical sheet 14, the optical sheet 14 having high diffraction efficiency is formed.
[0053]
Also in this optical sheet 14, the blazed diffraction gratings according to the first and second embodiments are arranged in each cell 10 as shown in FIG. 6B. Then, as shown in FIG. 6 (c), each blazed diffraction grating arranged in each cell 10, the spatial frequency is the inverse of the lattice spacing d _y optical surfaces L in the light incident surface, the optical against the light incident surface The inclination angle φ of the working surface L and the diffraction efficiency of the incident light on the optical working surface L are set to predetermined values. In this way, as shown in FIG. 6A, an optical sheet 14 composed of the cells 10 is obtained. The optical sheet 14 thus formed can be stably molded with high precision even in the molding step.
[0054]
Since the display according to the present embodiment is configured as described above, the spatial frequency of the blazed diffraction grating disposed in the cell 10, the inclination angle φ of the optical working surface L, the diffraction efficiency, and the area of the cell 10 By accurately designing and setting, a full-color image or an image having parallax can be displayed. Also, it is possible to stably mold with high precision in the molding step.
[0055]
In addition, by arranging the blazed diffraction gratings according to the first and second embodiments on the surface, it is possible to realize a uniform optical sheet 14 having high diffraction efficiency and uniform quality.
[0056]
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.
[0057]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a blazed diffraction grating having high diffraction efficiency, high moldability during duplication, and capable of stably duplicating.
[0058]
Also, by forming such a blazed diffraction grating on the sheet surface, an optical sheet having excellent diffraction efficiency and excellent moldability can be realized.
[0059]
Further, by forming such a blazed diffraction grating in a cell and displaying an image using the cell as a pixel, it is possible to realize a display body which is excellent in moldability and which is brightly displayed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a blazed diffraction grating according to a first embodiment; FIG. 2 is a vertical sectional view showing the vicinity of the surface of the blazed diffraction grating according to the first embodiment; FIG. 4 is a conceptual diagram for explaining a method of duplicating a blazed diffraction grating according to the second embodiment. FIG. 4 is a vertical sectional view showing the vicinity of the surface of the blazed diffraction grating according to the second embodiment. FIG. 6 is a conceptual diagram showing an example of a display using a blazed diffraction grating according to the second embodiment. FIG. 6 is a conceptual diagram showing an example of an optical sheet using the blazed diffraction grating according to the first and second embodiments. FIG. 7 is a perspective view showing an example of a blazed diffraction grating according to the prior art. FIG. 8 is a conceptual diagram for explaining a method of duplicating the blazed diffraction grating according to the prior art.
d _y : lattice spacing, β: emission angle, α: emission angle of 0th-order diffracted light, β: emission angle of 1st-order diffracted light, φ: inclination angle, θ: incident angle, w: inclination angle, A: incident light, B1 B5: Boundary, D: Diffracted light, L: Optical working surface, M, M1, M2: Non-optical working surface, 2, 6, 20: Blazed diffraction grating, 4, 22: Light incident surface, 10: Cell, 12 ... Display body, 14 ... Optical sheet, 24 ... Mold, 26 ... Molded object

Claims (6)

In a blazed diffraction grating in which the vertical cross-sectional shape of the light incident surface forms a saw blade shape,
An optically active surface in which the vertical cross-sectional shape is formed as a straight line so that the incident light incident on the light incident surface acts optically, and the vertical cross-sectional shape is formed as a curve so that the incident light does not optically operate. And a blazed diffraction grating having a vertical cross-sectional shape formed of a straight line and a curved line by alternately disposing the non-optically acting surfaces on the light incident surface. In a blazed diffraction grating in which the vertical cross-sectional shape of the light incident surface forms a saw blade shape,
The inclination of the optically active surface, in which the vertical cross-sectional shape is formed as a straight line so that the incident light incident on the light incident surface acts optically, and the vertical cross-sectional shape is curved so that the incident light does not optically operate. A first boundary where the inclination of the non-optically active surface formed in step 2 coincides, and a second boundary where the inclination of the non-optically active surface does not coincide with the inclination of the optically active surface are alternately formed on the light incident surface. A blazed diffraction grating that is arranged and connects the optically active surface and the non-optically active surface at each of the boundaries to form the saw blade shape. The blazed diffraction grating according to claim 1 or 2,
A blazed diffraction grating in which a radius of curvature of a curve forming the non-optically active surface is set to 10% or more and 80% or less of an arrangement pitch of the optically active surface on the light incident surface. In a blazed diffraction grating in which the vertical cross-sectional shape of the light incident surface forms a saw blade shape,
An optically active surface in which the vertical cross-sectional shape is formed as a straight line so that the incident light incident on the light incident surface optically acts; and a plurality of straight lines in which the vertical cross-sectional shape is formed so that the incident light does not optically act. And a non-optical working surface formed by combining the blazed diffraction gratings on the light incident surface to form the saw blade shape. An optical sheet comprising the blazed diffraction grating according to any one of claims 1 to 4 arranged on a sheet surface. 5. The arrangement of the blazed diffraction grating according to claim 1 in a plurality of cells, and the arrangement of the optically active surface on the light incident surface for each of the blazed diffraction gratings disposed in each of the cells. By setting the spatial frequency, which is the reciprocal of the pitch, the angle of inclination of the optically active surface with respect to the light incident surface, and the diffraction efficiency of the incident light on the optically active surface to a predetermined value, each cell becomes a pixel. Display body that displays an image.

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