JPH08313712A - Diffraction grating pattern and its production - Google Patents

Abstract

PURPOSE: To provide a production method of a Lippman diffraction grating pattern having cells comprising diffraction gratings as the structural units by using a simple device and operation. CONSTITUTION: A light-reflecting body having a reflecting surface in which the direction of reflection or diffusion of light or scattering property of light is specified for each area is used as a master substrate. A photosensitive material is disposed near the substrate. Coherent light is made to irradiate the photosensitive material so that the light transmitting through the photosensitive material interferes with the light transmitting through the photosensitive material and reflected by the substrate to duplicate the substrate pattern on the photosensitive material by exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating pattern formed by arranging a fine diffraction grating (grating) for each cell (dot) on the surface of a substrate, and more particularly, by interfering laser light. , A method for producing a pattern composed of a dot-shaped diffraction grating.

[0002]

2. Description of the Related Art The following method is known as a method for obtaining a display having a diffraction grating pattern by arranging a plurality of minute dots made of a diffraction grating on a surface of a substrate by interference of two light beams of laser light. is there.

As a two-beam interference method, Japanese Patent Laid-Open No. 60-156004 and Japanese Laid-Open Patent Application No. 5-241007 by the present applicant.
A series of methods typified by Japanese Patent Publications and the like are known. In this method, two coherent light beams (laser beams) are crossed on a photosensitive material, and the coherent light beams are made to interfere with each other by exposing in dot units, so that minute interference fringes (diffraction grating) formed on the dots. Is a method of forming a pattern composed of a collection of diffraction grating dots (cells) by sequentially changing the pitch, the direction, and the light intensity and performing exposure recording.

[0004]

In the known two-beam interferometry method, a complicated optical system (at least a laser light source, a shutter, beam splitting means, an imaging system for intersecting the beams, and a stage on which a photosensitive material is mounted are mounted. , A means for driving the stage as desired) is required, and when changing the spatial frequency (pitch of the grating stripes) or the direction (direction of the grating stripes) of the diffraction grating, a part of the optical system is required for each spatial frequency or direction. Is required to change the incident angle or the incident direction of light. In addition, it takes a lot of time and labor to produce a large-sized or complicated diffraction grating pattern.

It is an object of the present invention to provide a method capable of producing a large-sized or complicated diffraction grating pattern by a simple device / operation.

[0006]

In order to achieve the above object, the following known techniques are used in combination.

(1) Image Forming Body Producing Opal Effect As an image forming body that produces a special visual effect by utilizing the physical phenomenon of “reflection” rather than “diffraction”, the applicant of the present application, Sho 62-10116. What is illustrated in the publication is known.

The image forming body has a metal surface (reflection surface),
A plurality of line-shaped corrugated concavo-convex pattern groups are assembled, and the line direction in each of the pattern groups is changed in various directions, and the cross-sectional shape of the pattern group is substantially sinusoidal. , The pitch is 0.08 mm to 0.13 mm, and the ratio of the pitch width to the emboss depth is 7: 1 to 10: 1.

In the image forming body, since the line direction in each line-shaped uneven pattern group forming the embossed pattern formed on the surface is swung in various directions,
Since the reflection direction of the reflected light on the pattern surface changes variously, when the viewing angle and direction are changed variously, the shade and brightness of each line-shaped uneven pattern group dynamically change (called opal effect), It produces an extremely beautiful effect.

(2) Contact copy of Lippmann hologram A photosensitive material is brought into close contact with a master (original plate) of Lippmann hologram, and coherent light is incident from the photosensitive material side.
A method is also known in which the light transmitted through the photosensitive material and the reproduction light of the hologram image transmitted through the photosensitive material and diffracted by the master are interfered with each other to expose and duplicate the pattern of the master on the photosensitive material.

That is, the method for producing a diffraction grating pattern proposed in the present invention is the same as the above-mentioned (1) image forming body (light reflector).
As a master substrate, the photosensitive material is disposed in close proximity to the substrate, coherent light such as laser light is incident from the photosensitive material side, and light that passes through the photosensitive material and the image forming body that passes through the photosensitive material. A diffraction grating that reflects or diffuses light only in a specific direction, or a diffraction grating that scatters light in multiple directions by interfering with reflected light and exposing and duplicating the master pattern on a photosensitive material. This is a method for producing a volume phase type (Lippmann type) diffraction grating pattern having cells as constituent units.

[0012]

In the two-beam interference method exemplified in the above publication, the diffraction grating pattern formed on the photosensitive material is a relief type (interference fringes are recorded in the form of unevenness. The depth of the unevenness is 1 μm.
m or less). The present invention is a Lippmann type diffraction grating pattern, and interference fringes are recorded in the form of a transmittance distribution or a refractive index distribution in the thickness direction of the photosensitive material.

Since the contact copy method is used, it is not necessary to divide the laser beam into two light beams and cross them on the photosensitive material as in the existing method, and each area (reflection surface) formed on the master substrate is A cell unit pattern is easily produced.

The spatial frequency and the direction of the diffraction grating to be manufactured change depending on the direction of the reflected light from the light reflector. These determine conditions such as a visible direction and a visible color when observing the manufactured diffraction grating.

By using a light reflector having a plurality of regions that reflect (or diffuse / scatter) light in different directions,
A pattern that is supposed to be observed from multiple directions can be produced by a single exposure.

Further, the image forming body (light reflector) of the above (1)
Is because the cross-sectional shape of the line-shaped corrugated concavo-convex pattern group formed in the cell (region) that determines the reflection / diffusion direction is rougher than the concavo-convex pattern of the lattice stripes formed in the existing diffraction grating pattern. It is easier to fabricate any of the image forming bodies than to fabricate a diffraction grating pattern by a conventional method.

[0017]

EXAMPLE FIG. 1 shows an outline of a manufacturing method according to the present invention. Place the photosensitive material in close contact on a light reflector (master substrate) that has a light-reflecting surface in which the direction of light reflection (diffusion) is specified for each area, and make sure that the light-sensitive material is parallel with a sufficient width from the photosensitive material side. Light (coherent light) is incident.

FIG. 2 shows how light is reflected on a light-reflecting surface (mirror surface, corresponding to claim 4) which is an area constituting the master substrate. In this case, with respect to the incident light, the outgoing angle γ of the reflected light is determined depending on the inclination angle θ of the light reflecting surface. When the incident angle of the incident light is α, γ = 2θ−α.

FIG. 3 shows the interference of light in a photosensitive material placed in front of a light reflecting surface. That is, incident light is incident on the photosensitive material, and the transmitted light reaches the light reflecting surface depending on the transmittance of the photosensitive material. On the light reflecting surface, the above reflection angle γ
The light is reflected by, and the incident light and the reflected light interfere with each other on the photosensitive material, and interference fringes are recorded in the photosensitive material as a transmittance distribution or a refractive index distribution.

On the light reflector shown in FIG. 1, these light reflecting surfaces are used as area units and the units are arranged as desired.
Since each light reflecting surface reflects light in a predetermined direction, a diffraction grating corresponding to the outgoing direction of the reflected light is formed in each region in the photosensitive material according to each light reflecting surface. It

Therefore, a diffraction grating pattern is recorded in a necessary area by only exposing the coherent light spread over the entire surface of the master substrate once.

There is also a method in which not only the spread coherent light is exposed on the entire surface of the master substrate, but also scanning exposure is performed so that the beam-shaped coherent light is spread over the entire surface of the master substrate. In this case, needless to say, the time required for the exposure is longer than that of the batch exposure, but the exposure time can be shortened for the unit area on the photosensitive material, and the influence of the vibration of the optical system is less likely to occur. . Further, it becomes possible to freely adjust the exposure intensity depending on the exposure position.

Alternatively, by arbitrarily selecting the exposure / non-exposure depending on the position, it becomes possible to provide the photosensitive material with a portion where the diffraction grating pattern is formed and a portion where the diffraction grating pattern is not formed. Depending on the presence / absence), a pattern display different from the pattern formed by the combination of the regions formed on the master substrate can be performed.

The above-mentioned pattern display depending on the presence or absence of diffraction can be performed not by scanning exposure but by exposing through a mask that selectively transmits the expanded coherent light. (Corresponding to claim 7)

If the light reflector (master substrate) is arranged in advance so as to express an image or a character (claim 2)
Corresponding), the obtained diffraction grating pattern can display them.

At this time, since the diffraction grating cell is not formed in the photosensitive material in the region where the master substrate does not have the light reflecting surface and the light diffusing surface, an image with high contrast can be obtained.
(Corresponding to claim 6 and claim 7)

FIG. 4 shows an example of a plurality of types of light reflectors (regular reflection surface / diffuse reflection surface) in which the angles of the reflection surfaces of the regions constituting the master substrate are different. Each of the six types of reflecting surfaces shown in the same drawing corresponds to one region (one cell of the manufactured diffraction grating).

The left master substrate has the largest inclination angle of the reflecting surface, and when the master substrate is subjected to exposure duplication, all the reflected light from the reflecting surface does not reach the photosensitive material (since it has a sawtooth shape, it is shielded). There is also a component) which is not included in the entire surface of the photosensitive material.

As the photosensitive material is brought into close contact with the master substrate, the above factors are reduced, and the degree of forming the diffraction grating over the entire surface of the photosensitive material is increased. This is more remarkable in the case of the regular reflection surface and the diffuse reflection surface, as long as the sawtooth pitches are equal, the right master substrate (the inclination angle of the reflection surface is small). Also, if the inclination angles of the reflecting surface are equal, the same can be said when the sawtooth pitch is small (that is, the reflecting surface is finely divided).

FIG. 5 shows an example of a light reflector in which each region is specularly reflected (specular reflection). That is, each region of the light reflector (and the entire master substrate) has a uniform flat surface and is a mirror surface that specularly reflects incident light only in a direction depending on the arrangement angle of the flat surface. Since the arrangement angle is uniform and the light is reflected only in a specific direction (corresponding to claim 4), the diffraction grating cell to be produced is very simple, and the diffracted light is reduced in a specific direction. Brightness is also high. In particular,
This is even more pronounced if the region without the specularly reflective surface has a light-transmitting / light-absorbing property (corresponding to claim 6).

FIG. 6 shows that each region has a light diffusing property in only one direction (in the figure on the left, the reflection from the reflection point within the plane of the paper,
Only the reflection angle is different, and it reflects with a certain distribution)
An example of a light reflector is shown. Since the diffused light reflects with a specific distribution depending on the distribution of the inclination of each region (claim 5
The corresponding diffraction grating cell has a function of diffusing light only in a specific direction. Regarding the diffusion direction, it is possible to observe the diffracted light from a wide angle within a specific directivity (within the plane of the paper), but it is difficult to observe the diffracted light from other angles.

On the other hand, when a light reflector having a function of scattering light is used, the diffraction grating to be produced becomes complicated, has a property of scattering light, and diffracted light can be observed from a wide range. Become.

In the present invention, "diffusion" means having a specific directivity (in a certain plane in FIG. 6) and reflecting with a distribution according to the angle, and "scattering". Means that there is no specific directivity, that is, the directions and angles are reflected at random.

FIG. 7 shows the correspondence between the reflection surface and the diffraction grating to be manufactured in the specular reflection surface (specular reflection surface). The pitch D of the lines on the light reflecting surface of the master substrate is usually on the order of several tens of μm or more, and can be easily formed by chemical etching or physical cutting.

On the other hand, the pitch d (generally in the submicron order) of the diffraction grating formed in the photosensitive material depends on the incident angle and the reflection angle at the time of exposure, and therefore on the inclination angle of the light reflecting surface. To do.

Further, in the Lippmann type (volume phase type) diffraction grating (hologram), interference fringes are recorded in the thickness direction due to interference of light rays from the front and back of the photosensitive material. In the relief type (convex surface type), interference fringes due to interference of light rays from one surface of the photosensitive material become uneven due to development processing. (See the conceptual diagram in Figure 11)

In the present invention, a complicated and fine diffraction grating can be easily formed simply by producing a relatively rough light reflector (master substrate).

For example, as shown in FIG. 8, if the outer shape of the light reflector is arbitrary, the diffraction grating to be manufactured will also have the same shape, and a more complicated pattern can be formed very easily.

FIG. 9 shows an example of the light reflector (master substrate). For example, assuming that the portions a and b are specular reflection surfaces and the portion c is a light diffusion surface, the diffraction grating pattern produced is as shown in FIG.

That is, the areas A and B of the diffraction grating pattern
Are formed by simple diffraction gratings, so they are very bright, but diffracted light is observed only from a limited direction.

The portion C shines relatively dullly, but the diffracted light can be observed from a wider range than A and B. Therefore, by combining these simple diffraction gratings and complicated diffraction gratings, it is possible to obtain the effect of attracting the observer's attention at the portion C and observing a high-luminance image at the portions A and B. Can be issued.

Further, by appropriately designing the light reflection directions of the respective light reflectors and appropriately setting the observable viewpoint positions, it is possible to change the observed image with the viewpoint change. Various effects can be easily realized.

Further, when a pattern having a light scattering effect is formed at the same time, a more varied image can be observed.

[0044]

The remarkable effects of the present invention are listed below. a) Since only one light beam needs to be incident on the photosensitive material and the master substrate, the optical system can be simple, and it is less susceptible to external influences such as vibration, and a diffraction grating pattern can be stably produced. . b) Since a fine diffraction grating can be produced from a light reflector having a rough structure, if the light reflector is appropriately made by a simple method such as chemical etching or physical cutting, the master substrate can be changed appropriately. Therefore, a complicated pattern can be easily manufactured. c) It is not necessary to control the optical system for each spatial frequency or for each direction of the diffraction grating to perform independent exposure, and the manufacturing process becomes very simple. d) The light reflector has an inclined surface, but if the area of each light reflection surface is sufficiently small, the distance to the photosensitive material can be sufficiently close at all positions on the light reflector and is stable. Thus, a highly accurate diffraction grating pattern can be manufactured. Therefore, a high quality image can be expressed. e) When a light-reflecting surface, which is a flat mirror surface, is used in a region inside the light-reflecting body, a simple diffraction grating composed of linear grating fringes is recorded and observable in the corresponding photosensitive material portion. Although the viewpoint is limited, a diffraction grating with high brightness during observation is produced. f) When a light diffusing region is used in the region inside the light reflector,
A diffraction grating having a function of diffracting light in a relatively wide range according to its diffusivity is recorded in a corresponding photosensitive material portion, and a diffraction grating having a relatively wide visual range that appears to shine from a specific range is manufactured. . g) By making a portion of the light reflector other than the light reflecting surface or the light diffusing surface have a function of absorbing or transmitting light, only reflected light (or diffused light) from the light reflector can be interfered with. Therefore, a diffraction grating pattern with good S / N can be manufactured. h) When a light scattering area is used in the area inside the light reflector,
A diffraction grating having a function of diffracting light in a very wide area is recorded in a portion of the corresponding photosensitive material in the portion corresponding to the area, and a diffraction grating having a wide visual range that can be seen as shining from a wide area is manufactured. . i) By arbitrarily selecting the exposure / non-exposure depending on the position, it becomes possible to freely provide the photosensitive material with a portion where the diffraction grating pattern is formed and a portion where the diffraction grating pattern is not formed. It is also possible to display a pattern different from the pattern formed by the combination of the areas formed on the master substrate. j) A complicated diffraction grating pattern can be easily and stably manufactured in an extremely short time. In addition, the diffraction grating pattern obtained by the present invention can set an observable viewpoint for each region corresponding to the light reflector, becomes very complicated, and has high visual effects and security.

[0045]

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of a manufacturing method according to the present invention.

FIG. 2 is an explanatory diagram showing how light is reflected on a light reflecting surface (mirror surface).

FIG. 3 is an explanatory diagram showing light interference in a photosensitive material.

FIG. 4 is an explanatory diagram showing a plurality of types of light reflectors having different reflection surface angles.

FIG. 5 is an explanatory diagram showing a light reflector in which each region is specularly reflected.

FIG. 6 is an explanatory view showing a light reflector in which each region has a light diffusing property in only one direction.

FIG. 7 is an explanatory diagram showing a correspondence between a reflecting surface and a diffraction grating to be manufactured.

FIG. 8 is an explanatory diagram showing the correspondence between the shape of the reflecting surface and the shape of the diffraction grating to be produced.

FIG. 9 is an explanatory diagram showing an example of a light reflector (master substrate).

10 is an explanatory diagram showing an example of a diffraction grating manufactured corresponding to FIG.

FIG. 11 is a schematic view conceptually showing interference fringe recording on a photosensitive material.

Claims (8)

[Claims] 1. A master substrate is a light reflector having a light reflection surface whose light reflection direction, diffusion direction, or light scattering property is specified for each region, and a photosensitive material is provided on the light reflection surface side of the substrate. They are placed close to each other, and coherent light is incident from the side of the photosensitive material. The light that passes through the photosensitive material interferes with the light that passes through the photosensitive material and is reflected by the light reflecting surface of the substrate. Is recorded as a cell composed of a diffraction grating corresponding to the area, and a pattern corresponding to the substrate is prepared using the cell as a constituent unit. 2. Each area of the light reflector is used as a pixel, and a group of the pixels is used to form an arbitrary image or character by using the light reflector having an arbitrary image or character formed on the light reflecting surface as a master substrate. The method for producing a diffraction grating pattern according to claim 1, wherein the produced diffraction grating pattern is produced. 3. A master substrate having a different reflected light intensity and a different reflection angle is arbitrarily used for each region of the light reflector, and the color and brightness of each cell of the diffraction grating pattern is arbitrarily changed according to the substrate. The method for producing a diffraction grating pattern according to claim 1 or 2, wherein 4. A master substrate having a uniform flat surface and having a mirror surface that specularly reflects incident light only in a direction depending on an arrangement angle of the flat surface as at least one region of the light reflector. The method for producing a diffraction grating pattern according to any one of claims 1 to 3. 5. A master substrate having a light diffusive reflective surface having light diffusiveness only in a specific direction as at least one region of a light reflector is used. A method for producing the described diffraction grating pattern. 6. A light reflector having a portion that absorbs or transmits light is used as a master substrate, so that a portion where a diffraction grating is formed and a portion where a diffraction grating is not formed are formed according to the substrate. A method for producing a diffraction grating pattern according to claim 1, wherein a pattern is produced. 7. A light-transmissive substrate having a specific pattern formed by a light-shielding portion is disposed in proximity to either one side of a photosensitive material, thereby forming a diffraction grating pattern corresponding to a master substrate. The diffraction grating according to any one of claims 1 to 6, wherein the specific pattern is formed according to a light shielding portion of the translucent substrate and a portion where a diffraction grating is not formed. How to make a pattern. 8. A diffractive grating that reflects light in a specific direction, a diffractive grating that diffuses light in a specific direction, a diffractive grating that scatters light in a wide range, and a portion where no diffractive grating exists, and at least two types are appropriately selected. Volume phase type diffraction grating pattern having the cells of as a constituent unit.