JPH0572405A - Diffraction grating plotter - Google Patents

Abstract

PURPOSE:To continuously and uniformly manufacture a diffraction grating, which is tolerant to external vibration and has an optional spatial frequency in an optional direction, to obtain extremely high light utilization, and to make the size of the diffraction grating variable. CONSTITUTION:This diffraction grating plotter is equipped with an X-Y-theta stage 6 which moves and rotates a dry plate 3, a laser light source 7, a shutter 8 which is opened and closed to expose and not to expose the dry plate 3 to a laser beam, an optical branching means 9 which branches the laser beam into two, a 1st optical system which makes one laser beam incident as a reference beam on the dry plate 3, and a 2nd optical system consisting of a rotatable mirror 13 which is movable in parallel and in a specific direction and receives and reflects the other laser beam at the position of the center of rotation to make its reflected light as an object beam on the dry plate 3 at the same position with the reference beam or a position deviating from it, and a control means 16 which controls the X-Y-theta stage 6, shutter 8, and rotary moving mirror 13 according to image data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a diffraction grating by using a laser beam and interference of two light beams thereof,
In particular, the present invention relates to a diffraction grating plotter capable of continuously producing a diffraction grating having an arbitrary spatial frequency in an arbitrary direction at an arbitrary position.

[0002]

2. Description of the Related Art Generally, an interference fringe is recorded by using a coherent light source such as a laser light source, and dividing a laser beam from this into two light fluxes once and exposing them again on a photosensitive material at the same time. .. The pitch of the interference fringes (the reciprocal of the spatial frequency) changes depending on the angle difference between the two light beams incident on the photosensitive material, the direction changes depending on the direction in which the two light beams enter, and the recorded density is the light intensity. Depends on That is, during observation, the pitch of the interference fringes is related to the visible color, the direction of the interference fringes is related to the visible direction, and the density of the interference fringes is related to the brightness of the visible color.

A method of forming a diffraction grating by the interference of two light fluxes to manufacture a display having a diffraction grating pattern in this manner is described in, for example, "JP-A-60-1".
No. 56004, "Japanese Patent Application No. 63-222477"
Etc. have been proposed.

That is, first, the former method uses a diffraction grating exposure head, and by moving this diffraction grating exposure head, minute interference fringes (hereinafter referred to as a diffraction grating) due to two-beam interference are formed at the pitch, This is a method of changing the direction and the light intensity, successively exposing the photosensitive material, and producing an arbitrary diffraction grating at an arbitrary position. By using this method, a display including a flat photosensitive material and a diffraction grating pattern formed on the surface thereof can be obtained. Since this diffraction grating pattern is composed of a plurality of minute dots formed by the diffraction grating, each dot shines in each color in each direction with each intensity, and various patterns are drawn. ..

On the other hand, in the latter method, dots made of a diffraction grating are formed at corresponding positions on a dry plate (made of glass coated with a photosensitive material) on an XY stage according to image data read from a computer. Is the way to go. By using this method, a display with an almost perfectly uniform diffraction grating pattern is obtained.

However, first, the former manufacturing method has the following problems. That is, when changing the pitch, direction, or light intensity of the diffraction grating, it is necessary to move the optical system of the diffraction grating exposure head each time. Since the optical system cannot be fixed in this way, it is weak against vibration and is easily affected by external vibration. Therefore, there is a problem that not only a long waiting time is required to sufficiently damp the vibration but also the stability of the production of the diffraction grating is poor, and a uniform (highly accurate) diffraction grating cannot be produced.

On the other hand, the latter manufacturing method has the following problems. That is, since the laser beam is branched into several beams and one of them is selected to determine the spatial frequency of the diffraction grating to be produced, there is a problem that the light utilization efficiency is very low. Also,
The number of beams to be branched is limited to about three because the spatial arrangement of the optical system and the light intensity become weak. Therefore, there is a problem that only a diffraction grating having about three kinds of spatial frequencies can be produced (the spatial frequency of the diffraction grating is limited to about three kinds).

[0008]

As described above, in the conventional manufacturing method, it is not possible to manufacture a uniform diffraction grating that is strong against external vibration, and the spatial frequency of the diffraction grating is limited. However, there is a problem in that the light utilization efficiency is low.

The present invention was made in order to solve the above-mentioned problems, and it is strong against external vibrations, and a diffraction grating in an arbitrary direction having an arbitrary spatial frequency is continuously formed at an arbitrary position. Therefore, it is an object of the present invention to provide a diffraction grating plotter that can be manufactured uniformly and has extremely high light utilization efficiency.

[0010]

In order to achieve the above object, the present invention uses a laser beam to coat a photosensitive material for forming a diffraction grating in an apparatus for producing a diffraction grating by the two-beam interference. An XY-θ stage that moves and rotates the dry plate, a laser light source that generates a laser beam, and a shutter that receives the laser beam from the laser light source and performs exposure and non-exposure by opening and closing the laser beam. And a light splitting means for splitting the laser beam from the shutter into two laser beams,
A first optical system for making one of the laser beams from the light splitting means incident on the dry plate as a reference beam, and receiving and reflecting the other laser beam from the light splitting means at its rotation center position, and reflecting the same. A first rotating / moving mirror that is rotatable about the center of rotation as a fulcrum and that is movable in parallel in a predetermined direction. 2 based on the optical system and the read image data, XY
A control means for controlling the movement and rotation of the stage, the opening and closing of the shutter, and the rotation angle and movement position of the rotation / moving mirror.

Here, in particular, the opening time of the shutter is controlled.

[0012]

Therefore, in the diffraction grating plotter according to the present invention, the rotating angle of the rotating mirror is continuously controlled to an arbitrary value in accordance with the read image data.
It is possible to uniformly manufacture a diffraction grating having an arbitrary spatial frequency. Further, by moving and rotating the XY-θ stage to a position corresponding to the read image data, it is possible to fabricate a diffraction grating in any position on the photosensitive material. Further, the depth of the diffraction grating can be changed by controlling the opening time of the shutter, that is, the brightness of the dots of the diffraction grating at the time of observation can be changed. Furthermore, the size of the diffraction grating can be changed by making the object beam incident on the dry plate at a position shifted from the incident position of the reference beam.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, two laser beams, namely a laser beam serving as a reference beam, are used.
It is divided into a laser beam that becomes an object beam and X-Y-
On the photosensitive material of the dry plate placed on the θ stage, each is made incident at a preset angle to cause interference, and the exposure or non-exposure of the laser beam is controlled by opening and closing the shutter, and XY-θ When the diffraction grating is produced by moving the stage relatively and arranging a plurality of minute dots consisting of the diffraction grating on the surface of the photosensitive material of the dry plate, the laser beam which is the reference beam is preset. While making it incident on the photosensitive material of the dry plate at a fixed angle (fixed angle), while controlling the incident angle of the laser beam, which becomes the object beam, by the turning / moving mirror continuously (variable angle). , Always on the photosensitive material of the dry plate at the same position as the reference beam or at a shifted position, that is, the relative angle between the reference beam and the object beam is arbitrarily set. It is variable so that both laser beams interfere with each other.

The above method is based on the following grounds. That is, the relationship between the incident light and the diffracted light is shown in FIG.
The relationship is as shown in. Further, the incident angle θ of the object beam at the time of making the diffraction grating, the observable angle β at the time of observation,
The relation with the color (reconstruction wavelength λ) is expressed by the following equation. (1 / λ) (sin α-sin β) = (1 / λ ₀ ) (sin α ₀ −sin θ) where λ is the wavelength of the diffracted light (observed color), α is the incident angle of the illumination light, β is the outgoing angle (observation position) of the diffracted light, λ ₀ is the wavelength of the laser beam at the time of fabrication, α ₀ is the incident angle of the reference beam, and θ is the incident angle of the object beam.

When the diffraction grating manufactured under the conditions shown in FIG. 8 is illuminated with white light, the light is diffracted by satisfying the above expression as shown in FIG. Therefore, if the exit angle (observation position) β of the diffracted light is determined by continuously controlling the incident angle θ of the object beam to an arbitrary value, it is possible to fabricate a diffraction grating composed of dots that can be seen in any arbitrary color. Become. λ = λ ₀ (sin α−sin β) / (sin α ₀ −sin θ) In other words, the spatial frequency f of the diffraction grating is represented by f = (sin α ₀ −sin θ) / λ ₀ .. Therefore, a diffraction grating having an arbitrary spatial frequency can be manufactured by continuously controlling the incident angle θ of the object beam to an arbitrary value.

An embodiment of the present invention based on the above concept will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing a method of manufacturing a diffraction grating by two-beam interference according to the present invention. That is, as shown in FIG. 1, when two laser beams 1 and 2 are made to cross each other in a dot shape on a dry plate 3 coated with a photosensitive material, a diffraction grating 5 is formed in a dot 4. The pitch of this diffraction grating 5 is
It can be changed by changing the angle at which the two laser beams 1 and 2 intersect. The dots 4 of the diffraction grating 5 are formed on the surface of the photosensitive material of the dry plate 3 while moving the XY-θ stage 6 according to the instruction of the computer.

FIG. 2 is a schematic diagram showing a structural example of a diffraction grating plotter for forming dots on the surface of the photosensitive material of the dry plate.

In FIG. 2, the diffraction grating plotter of this embodiment is provided with a dry plate 3 coated with a photosensitive material for forming a diffraction grating, and the dry plate 3 is moved and rotated X-.
A Y-θ stage 6, a laser light source 7 for generating a laser beam, a shutter 8 for receiving and exposing the laser beam from the laser light source 7, and performing exposure / non-exposure by opening / closing it, and two laser beams from the shutter 8 Half mirror 9 which is an optical branching means for branching into a laser beam
And a first optical system consisting of two total reflection mirrors 10 and 11 for reflecting one laser beam from the half mirror 9 and making it incident on the dry plate 3 as a reference beam, and the other laser from the half mirror 9. The beam is received at its rotation center position and reflected, and the reflected light is always made incident on the dry plate 3 at the same position as the reference beam as an object beam. In this example, a rotating / moving mirror 1 that can move in parallel in the vertical direction.
2nd optical system consisting of 3 and the movement and rotation of the XY-θ stage 6, the opening and closing of the shutter 8, and the rotation angle and movement position of the rotation / moving mirror 13 based on the read image data. And a controller 16 which is a control means for controlling each of the above.

Next, the operation of the diffraction grating plotter of this embodiment will be described with reference to FIGS. 3 and 4.

First, the image data taken in by the scanner which is the image input means is read, and the image data is corrected by the decomposition and adjustment of the color information by the computer to set the viewing zone and the direction of observation. Create the data (dot data) of the diffraction grating pattern that contains it.

Next, the controller 16 moves the XY-θ stage 6 in the corresponding position and direction of this data, and also rotates and forms the spatial frequency of the diffraction grating according to this data. The rotation angle and the moving position of the moving mirror 13 are controlled, and the opening / closing time of the shutter 8 is controlled so that the brightness of the diffraction grating is in accordance with this data, so that the dry plate 3 coated with the photosensitive material is exposed. To do. At this stage, the process of forming the diffraction grating corresponding to the color determined for one dot is completed.

Next, it is determined whether or not the data exposure has been completed for all. As a result, if the exposure has not been completed for all the data, the above processes are repeated until the exposure for all the data is completed, and the process is completed when the exposure is completed for all the data. In this way, a display having a plurality of dot-shaped diffraction grating patterns is completed (after developing the photosensitive material).

That is, in the diffraction grating plotter of this embodiment, as shown in FIG. 5, two laser beams (reference beam and object beam) are intersected on the dry plate 3 and the diffraction grating 5 is formed at that time. Record dot 4 and dot 4
An image is created by a collection of.

Here, the reference beam passes through the two total reflection mirrors 10 and 11 and is incident on the photosensitive material surface of the dry plate 3 at a preset angle α. Further, the angle of incidence of the object beam on the surface of the photosensitive material of the dry plate 3 is arbitrarily controlled by the rotating / moving mirror 13, and the dry plate 3 has an incident angle of θ.
On the surface of the photosensitive material of the same position (1
Point). In this case, the incident angle θ of the object beam on the surface of the photosensitive material changes depending on the change of the rotation angle and the movement position of the rotation / moving mirror 13, but even if the rotation / moving mirror 13 rotates and moves, The incident position of the object beam on the surface of the photosensitive material does not change, and the reference beam exactly intersects the object beam on the surface of the photosensitive material, forming a diffraction grating there. Thereby, a diffraction grating having an arbitrary spatial frequency can be uniformly manufactured.

Further, by moving and rotating the XY-θ stage 6 to a position corresponding to the read image data, a diffraction grating in an arbitrary direction can be produced at an arbitrary position on the photosensitive material. Then, these diffraction gratings are automatically produced, and thereby a display expressing an image can be produced.

Further, by controlling the opening time of the shutter 8, the depth of the diffraction grating can be changed. This is equivalent to changing the brightness of the dots of the diffraction grating during observation.

As described above, in the diffraction grating plotter of this embodiment, the dry plate 3 coated with the photosensitive material for forming the diffraction grating is placed, and the dry plate 3 is moved and rotated X.
-Y-θ stage 6, a laser light source 7 for generating a laser beam, a shutter 8 for receiving and exposing the laser beam from the laser light source 7, and performing exposure / non-exposure by opening / closing it, and two laser beams from the shutter 8. A half mirror 9 which is a light splitting means for splitting into a laser beam and two total reflection mirrors 10 and 11 which reflect one of the laser beams from the half mirror 9 and make it enter the dry plate 3 as a reference beam. The optical system of No. 1 and the other laser beam from the half mirror 9 are received and reflected at the rotational center position, and the reflected light is made to be an object beam on the dry plate 3 at the same position as the reference beam at all times.
Based on the second optical system composed of a rotation / moving mirror 13 which is rotatable about the center of rotation and is movable in parallel in a predetermined direction (vertical direction in this example), and the read image data. , A controller 16, which is a control means for controlling the movement and rotation of the XY-θ stage 6, the opening and closing of the shutter 8, and the rotation angle and the movement position of the rotation / moving mirror 13, respectively. By interfering both laser beams of the object beam,
A diffraction grating is produced.

Therefore, the following effects can be obtained.

(A) Conventionally, when changing the pitch, direction, and light intensity of the diffraction grating, the optical system of the diffraction grating exposure head has to be moved each time, so that it is affected by external vibration. Although a uniform and uniform diffraction grating could not be obtained, in the diffraction grating plotter of the present embodiment, the rotation angle and the movement position of the rotation / moving mirror 13 are continuously controlled to arbitrary values. Since the incident angle of the object beam is variable, it is strong against external vibration, not only the waiting time for damping the vibration is unnecessary, but also the stability of the diffraction grating fabrication is improved. It is possible to manufacture a substantially uniform (highly accurate) diffraction grating.

(B) In the prior art, since the laser beam was used as it was and the laser beam was divided by a half mirror or the like, only about three types of diffraction gratings such as R, G and B could be produced. In the diffraction grating plotter of this embodiment, since the incident angle of the object beam is continuously variable to an arbitrary value, it is possible to continuously manufacture a diffraction grating having an arbitrary spatial frequency. (The spatial frequency of the diffraction grating is not limited to about 3 types).

(C) Conventionally, the spatial frequency of the diffraction grating to be produced is determined by branching the laser beam into several beams and selecting one of them, so that the light utilization efficiency is extremely high. On the other hand, since the diffraction grating plotter of this embodiment uses all of the laser beams branched into two, it is possible to remarkably increase the light utilization efficiency.

(D) Since the opening time of the shutter 8 is controlled, it is possible to change the depth of the diffraction grating, that is, the brightness of the dots of the diffraction grating during observation.

(E) Since the optical system is composed only of the rotatable / movable mirror 13 which is rotatable and movable in parallel,
The device configuration is extremely simple.

The present invention is not limited to the above-described embodiments, but can be implemented in the same manner as described below.

(A) In the above embodiment, the case where the opening time of the shutter 8 is controlled when the exposure is performed has been described, but the present invention is not limited to this, and when the exposure is performed, the shutter 8 is kept for a preset time. It is also possible to open.

(B) In the above embodiment, the case where the object beam is always incident on the dry plate 3 at the same position as the reference beam has been described, but the present invention is not limited to this and, for example, as shown in FIG. The reference beam may be incident on the dry plate at a position deviated from the incident position. By doing so, it is possible to change the size of the diffraction grating, that is, the brightness of the diffraction grating during observation.

[0038]

As described above, according to the present invention, a dry plate coated with a photosensitive material for forming a diffraction grating is placed, an XY-θ stage for moving and rotating the dry plate, and a laser. A laser light source for generating a beam, a shutter for receiving and exposing the laser beam from the laser light source, and exposing and non-exposure by opening and closing the beam, an optical branching unit for branching the laser beam from the shutter into two laser beams, and an optical branch. One laser beam from the means,
A first optical system that is incident on the plate as a reference beam;
A rotation center that receives the other laser beam from the light branching means at its rotation center position and reflects it, and makes the reflected light as an object beam always enter the dry plate at the same position as the reference beam or at a shifted position. A second optical system composed of a rotating / moving mirror which is rotatable about a position as a fulcrum and is movable in parallel in a predetermined direction, and based on the read image data, movement and rotation of the XY-θ stage, Since the control means for controlling the opening / closing of the shutter and the rotating angle and moving position of the rotating / moving mirror are provided, the structure is strong against external vibration and has an arbitrary spatial frequency. It is possible to fabricate a diffraction grating in any direction continuously and uniformly at any position. The light utilization efficiency is extremely high, the device configuration is simple, and the size of the diffraction grating can be adjusted as required. Diffraction grating plotter capable of varying can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of manufacturing a diffraction grating by two-beam interference according to the present invention.

FIG. 2 is an overall configuration diagram showing an embodiment of a diffraction grating plotter according to the present invention.

FIG. 3 is a schematic diagram for explaining the operation in the same embodiment.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

FIG. 5 is a view showing a formation example of the diffraction grating formed in the same example.

FIG. 6 is a schematic view showing another embodiment of the diffraction grating plotter according to the present invention.

FIG. 7 is a schematic diagram for explaining the concept of the present invention.

FIG. 8 is a schematic diagram for explaining the concept of the present invention.

FIG. 9 is a schematic diagram for explaining the concept of the present invention.

[Explanation of symbols]

1, 2 ... laser beam, 3 ... dry plate, 4 ... dot, 5 ...
Diffraction grating, 6 ... XY-θ stage, 7 ... Laser light source, 8 ... Shutter, 9 ... Half mirror, 10, 11 ...
Total reflection mirror, 12 ... Total reflection mirror, 13 ... Rotation / moving mirror, 16 ... Controller.

Claims (4)

[Claims] 1. An apparatus for producing a diffraction grating by using a laser beam by the two-beam interference thereof, wherein a dry plate coated with a photosensitive material for forming the diffraction grating is placed, and the dry plate is moved and rotated. A Y-θ stage, a laser light source that generates a laser beam, a shutter that receives and emits a laser beam from the laser light source, and performs exposure and non-exposure by opening and closing the laser beam, and a laser beam from the shutter into two laser beams. Optical branching means for branching, a first optical system for making one of the laser beams from the optical branching means incident on the dry plate as a reference beam, and the other laser beam from the optical branching means for its rotation center Received at a position and reflected, and the reflected light is always incident on the dry plate at the same position as the reference beam as an object beam, Based on the read image data, the XY stage based on the second optical system, which is composed of a rotating / moving mirror that is rotatable about the center of rotation and is movable in parallel in a predetermined direction. And a control means for respectively controlling the movement, rotation, opening and closing of the shutter, and the rotation angle and movement position of the rotation / moving mirror. 2. The diffraction grating plotter according to claim 1, wherein the opening time of the shutter is controlled. 3. In an apparatus for producing a diffraction grating by using a laser beam and interference of two light beams, a dry plate coated with a photosensitive material for forming the diffraction grating is placed, and the dry plate is moved and rotated. A Y-θ stage, a laser light source that generates a laser beam, a shutter that receives and emits a laser beam from the laser light source, and performs exposure and non-exposure by opening and closing the laser beam, and a laser beam from the shutter into two laser beams. Optical branching means for branching, a first optical system for making one of the laser beams from the optical branching means incident on the dry plate as a reference beam, and the other laser beam from the optical branching means for its rotation center It is received at a position and reflected, and the reflected light is incident as an object beam on the dry plate at a position deviated from the incident position of the reference beam. A second optical system composed of a rotating / moving mirror that is rotatable about the center of rotation as a fulcrum and is movable in parallel in a predetermined direction; and based on the read image data, the XY- A diffraction grating plotter comprising: a control unit that controls the movement and rotation of the θ stage, the opening and closing of the shutter, and the rotation angle and the movement position of the rotation / moving mirror. 4. The diffraction grating plotter according to claim 3, wherein the opening time of the shutter is controlled.