JPH05241008A - Diffraction grating plotter - Google Patents

Abstract

PURPOSE:To extremely simplify device constitution and adjustment and to enable the automatic and continuous formation of diffraction gratings having arbitrary shapes with good accuracy and simplicity without damaging a dry plate (photosensitive material). CONSTITUTION:This diffraction grating plotter has an X-Y stage 2 which moves a dry plate coated with the photosensitive material, a laser beam source 4 which generates a laser beam, a shutter 5 which receives the laser beam and executes exposing and non-exposing, a mask which is provided with blanked parts/light translucent parts of the shapes corresponding to the diffraction gratings having the arbitrary shapes and receives the laser beam from the shutter 5, a diffraction grating molding 7 which is formed with the diffraction grating and diffracts the laser beam to branch the beam to >=3 beams of the laser beams, a beam selecting means which allows the passage of prescribed two pieces of the laser beams selected from the respective laser beams, an imaging means 9 which images these two laser beams on the dry plate and a control means which controls the movement of the X-Y stage and the opening and closing of the shutter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for producing a dot-shaped diffraction grating by using a laser beam by interference of two light beams, and particularly, the device configuration is extremely simple and the adjustment of the device is extremely simple. Moreover, the present invention relates to a diffraction grating plotter capable of accurately and easily and automatically continuously producing a diffraction grating of any shape without damaging a dry plate (photosensitive material).

[0002]

2. Description of the Related Art In general, a coherent light source such as a laser light source is used to generate a laser beam from the laser beam once.
When the divided light beams are simultaneously exposed again on the photosensitive material, interference fringes are recorded.

The interference fringes have a pitch (the reciprocal of the spatial frequency) due to the difference in angle between the two light beams incident on the photosensitive material.
Changes depending on the direction of incidence of the two light beams, and the recorded density changes depending on the light intensity. 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, "Japanese Patent Laid-Open No. 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 comprising 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, a dot made of a diffraction grating is formed at a corresponding position 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 having 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 and 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, not only a long waiting time is required to sufficiently damp the vibration, but also the stability of the diffraction grating fabrication is poor, and a uniform (accurate) diffraction grating cannot be fabricated. There is.

On the other hand, the latter manufacturing method has the following problems.

That is, since the spatial frequency of the diffraction grating to be produced is determined by splitting the laser light into several and selecting one of them, there is a problem that the light utilization efficiency is very low. There is.

Also, the number of laser 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 manufactured (the spatial frequency of the diffraction grating is limited to about three kinds).

Therefore, recently, a diffraction grating plotter (for example, "Japanese Patent Application No. 3-231956") has been proposed by the present applicant as a device for solving the above problems.

However, in this type of diffraction grating plotter, XY (-
Two laser beams are incident on the (θ) stage through a predetermined device configuration. In most of these cases, there is no possibility of moving or rotating the incident side, and it is very difficult to reduce the size.

Further, not only the required laser beams must be adjusted so that they intersect each other on the surface of the dry plate, but also the rotation center of the θ stage and the intersecting position of the laser beams must be at the same position. It is very difficult to adjust these optical systems.

Further, even in the case of a movable / rotatable device structure, a diffraction grating exposure device (Japanese Patent Laid-Open No. 60-1560).
No. 04), it has a relatively large and complicated structure, and it is very difficult to adjust the alignment of the two light fluxes on the dry plate.

On the other hand, in order to manufacture a diffraction grating by the conventional method, it is necessary to bring the mask very close to the photosensitive material so that the two light beams are incident through the mask.

However, this is likely to damage the photosensitive material when the mask is moved when automatically exposing a plurality of locations. Therefore, if a gap is provided between the photosensitive material and the mask as shown in FIG. 7 so that the photosensitive material is not scratched, a diffraction grating of a desired shape is formed due to the displacement of the positions of the two light beams passing through the mask. Becomes impossible. Where 1
When only one exposure is required, it is possible to bring the photosensitive material and the mask into close contact with each other.
Due to the thickness of the mask, it is difficult to eliminate the displacement completely.

[0022]

As described above, in the conventional apparatus, the diffraction grating is formed with high accuracy, and the diffraction grating is manufactured so that there is no undesired deviation of the two light beams on the dry plate. Not only is it difficult to form a diffraction grating having a desired shape, but there is also a problem.

The present invention has been made to solve the above-mentioned problems, and has an extremely simple device configuration and extremely simple adjustment of the device, and is optional without damaging the dry plate (photosensitive material). An object of the present invention is to provide an extremely reliable diffraction grating plotter capable of producing a diffraction grating in the form of (1) accurately, simply and automatically in succession.

[0024]

In order to achieve the above object, in an apparatus for producing a dot-shaped diffraction grating by using a laser beam and interference of two light beams, first, in the invention described in claim 1, A dry plate coated with a photosensitive material for forming a diffraction grating is placed, and the dry plate is moved X
A Y stage, a laser light source for generating a laser light, a shutter for receiving and exposing the laser light from the laser light source to perform exposure and non-exposure, and a shape corresponding to an arbitrary-shaped diffraction grating to be formed. A mask that receives a laser beam from a shutter is provided with a cutout portion or a transparent portion, and a diffraction grating is formed. The laser light from the cutout portion or the transparent portion of the mask is diffracted and branched into three or more laser beams. Of the selected diffraction grating forming member and the laser light branched by the diffraction grating forming member.
A laser beam selecting means for passing two laser beams, an image forming means for focusing two laser beams selected by the laser beam selecting means on a dry plate, and movement of the XY stage based on the read data. , And control means for controlling opening and closing of the shutter, respectively.

On the other hand, in the invention described in claim 9, a dry plate coated with a photosensitive material for forming a diffraction grating is placed, an XY stage for moving the dry plate, and a laser light source for generating a laser beam. And a shutter that receives laser light from a laser light source and opens and closes to expose and non-expose, and a diffraction grating is created only in a preset area, and the laser light from the shutter is diffracted to create three or more lasers. A diffraction grating forming body that is branched into light, a laser light selecting unit that passes two selected predetermined laser beams among the laser beams that are branched by the diffraction grating forming unit, and 2 selected by the laser light selecting unit. Image forming means for forming two laser beams on a dry plate, and movement of the XY stage and opening / closing of the shutters based on the read data. Constitute a control means for controlling.

Here, in particular, as the mask, a spatial modulation element controlled by the control means is used. A liquid crystal display element is used as the spatial modulation element.

Further, the diffraction grating forming body is rotated in a plane perpendicular to the optical axis of the incident laser light based on the read data.

Further, the diffraction grating forming body and the mask are arranged in a plane perpendicular to the optical axis of the incident laser light,
The rotation is based on the read data.

On the other hand, a lens is used as the image forming means.

A holographic optical element is used as the image forming means.

Further, as the control means, the time during which the shutter is open is controlled.

[0032]

Therefore, in the diffraction grating plotter according to the present invention, the diffraction grating forming body having the diffraction grating formed thereon is used as a beam splitter to diffract the laser light and split the laser light into three or more laser lights. It is possible to always image two predetermined laser beams out of the light at the same position on the dry plate coated with the photosensitive material by the image forming means.

Further, at the time of passing through the mask, the light beam is transmitted almost perpendicularly to the mask with one light flux, so that a diffraction grating of any shape can be simply and automatically formed without causing the positional deviation as described above. You can

Further, the direction of the diffraction grating to be formed can be freely selected, and when a mask is used, the shape can be made arbitrary by using a spatial modulation element such as a liquid crystal display element as the mask.

As a result, the construction of the apparatus is extremely simple, the adjustment of the apparatus is extremely simple, and the dry plate (photosensitive material) is used.
Diffraction gratings of any shape can be continuously manufactured accurately, easily and automatically without damaging the.

[0036]

EXAMPLE The present invention is a diffraction grating plotter in which dot-shaped diffraction gratings are manufactured one after another by utilizing two-beam interference, and a previously prepared diffraction grating forming body having a diffraction grating is used as a beam splitter. The laser light is diffracted and branched into three or more laser lights, and two predetermined laser lights among the branched laser lights are always formed at the same position on the dry plate coated with the photosensitive material by the image forming means. It was made to image.

Further, in this case, the diffraction grating forming body which functions as a beam splitter is regarded as a master for copying, and (a) the diffraction grating forming body is formed in front of the master diffraction grating forming body (on the side where laser light is incident). It is set in advance when a mask provided with a cutout portion or a light-transmitting portion having a shape corresponding to an arbitrary-shaped diffraction grating to be formed is provided, or (b) when a diffraction grating formation body serving as a master is manufactured. The one in which the diffraction grating is produced only in the region where

Since each of these diffraction grating forming bodies diffracts incident light, for example, the + 1st order light and the −1st order light are selected to cause interference at the focusing position, and the interference fringes are recorded on the photosensitive material. Thus, a diffraction grating of any shape can be created.

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 schematic diagram showing a structural example of a diffraction grating plotter according to the present invention.

That is, in the diffraction grating plotter of this embodiment, as shown in FIG. 1, a dry plate 1 coated with a photosensitive material for forming a diffraction grating is placed, and an XY stage for moving the dry plate 1 is placed. 2, a laser light source 4 for generating a laser light 3, a shutter 5 for receiving and exposing the laser light 3 from the laser light source 4, and exposing and non-exposure by opening and closing thereof, and a mirror 6 for reflecting the laser light 3 from the shutter 5. And a cut-out portion or a light-transmitting portion having a shape corresponding to an arbitrary-shaped diffraction grating to be formed, and the shutter 5
A mask 11 for receiving the laser light 3 from the laser beam 3 and a diffraction grating are formed, and the laser light 3 from the cutout portion or the light transmitting portion of the mask 11 is diffracted and branched into three or more (three in this example) laser light. By the planar diffraction grating forming body 7, a stopper 8 which is a laser beam selecting means for passing two selected two laser beams selected from the laser beams branched by the diffraction grating forming body 7, and the stopper 8. Imaging system 9 for imaging the two selected laser beams on the dry plate 1.
And a controller 10 which is a control means for controlling the movement of the XY stage 2, the opening and closing of the shutter 5, and the mask 11 based on the read image data.

Here, for example, two lenses are used as the image forming system 9 and are arranged so that their image forming (focus) positions are present on the surface of the photosensitive material of the dry plate 1.

As the mask 11, a spatial modulation element (for example, liquid crystal display element) controlled by the controller 10 can be used.

Next, the operation of the diffraction grating plotter of this embodiment constructed as described above will be described.

First of all, the image data taken in from 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 10 moves the XY stage 2 to the position and direction corresponding to this data, and controls the opening / closing time of the shutter 5 so that the brightness of the diffraction grating is in accordance with this data. Then, exposure is performed on the dry plate 1 coated with the photosensitive material.

That is, the laser light 3 from the laser light source 4 is reflected by the mirror 6 through the shutter 5, and a mask provided with a cutout portion or a light transmitting portion having a shape corresponding to a diffraction grating of an arbitrary shape to be formed. The laser light 3 is diffracted by the diffraction grating forming body 7 which passes through 11 and further has a diffraction grating formed thereon, and is branched into three laser lights.
Then, of the branched laser lights, two selected predetermined laser lights are selected by the stopper 8, and the two laser lights are caused by the imaging system 9 to the dry plate 1.
Focused on top.

At this stage, the process of forming the diffraction grating corresponding to 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 plurality of dot-shaped diffraction grating patterns are completed (after developing the photosensitive material).

That is, in the diffraction grating plotter of this embodiment, two laser beams are crossed on the dry plate 1, dots formed by the diffraction grating formed at that time are recorded, and an image is produced by a collection of dots.

In this case, when the light is transmitted through the mask 11, the light is transmitted almost perpendicularly to the mask 11 with one light flux, so that the above-described positional deviation does not occur, and a diffraction grating of any shape can be easily and automatically operated. It is formed.

Further, the direction of the diffraction grating to be formed can be freely selected, and by using a spatial modulation element such as a liquid crystal display element as the mask 11, its shape can be made arbitrary.

Next, the operation of the main part of the diffraction grating plotter of this embodiment will be described more specifically with reference to FIGS.

Here, a case will be described in which two lenses 91 and 92 are used as the image forming system 9 and a diffraction grating is manufactured using ± 1st order diffracted light.

2 to 5, the same parts as those in FIG. 1 are designated by the same reference numerals.

Further, in FIG. 2, the stopper 8 is arranged between the two lenses 91 and 92 which are the image forming system 9, which is different from FIG. 1, but the diffraction grating forming body 7 and the dry plate 1 are different. It may be placed anywhere between and.

First, as a first step, as shown in FIGS. 2 and 3, when the laser light (wavelength λ) 3 is vertically incident on the diffraction grating forming body 7 serving as a beam splitter through the mask 11. Diffracted light other than ± 1st order is
The laser beam 3 is emitted at an angle β with respect to the optical axis.

Thereafter, a diffracted light other than the ± first-order light (including the transmitted light that is the zero-order light) is used as a mask or the like (the stopper 8 in this example)
And cut.

Sin β = λ / d ₀ Here, d ₀ is the pitch of the diffraction grating of the diffraction grating forming body 7 serving as the beam splitter.

Next, as a second step, as shown in FIGS. 2 and 4, the laser light 3 incident from the front focal position of the lens 91 of the image forming system 9 is rearward of the lens 91.
The laser light travels parallel to the optical axis (one-dot chain line in the figure).

When the laser light traveling parallel to the optical axis is incident on the lens 91, it becomes a laser light which is focused on the rear focal point of the lens 92.

The above system forms an image on the front focal plane of the lens 91 on the back focal plane of the lens 92.

At this time, the laser light 3 incident on the lens 91 at the angle β is emitted from the lens 92 at the angle θ.

Tan θ = (f ₁ / f ₂ ) tan β where f ₁ is the focal length of the lens 91 and f ₂ is the lens 9
The focal length is 2, which is equal to the focal length f ₁ of the lens 91 between the diffraction grating forming body 7 and the lens 91, and the distance between the lens 92 and the dry plate 1 is equal to the focal length f ₂ of the lens 92.

Next, as a third step, as shown in FIGS. 2 and 5, when two light fluxes are incident on the dry plate 1 at an angle of θ with respect to the perpendicular of the dry plate 1, they appear on the surface of the dry plate 1. The pitch d of the interference fringes is expressed as follows.

D = λ / 2 sin θ As described above, in the diffraction grating plotter of this embodiment, the dry plate 1 coated with the photosensitive material for forming the diffraction grating is placed, and the dry plate 1 is moved by X-. Y stage 2
A laser light source 4 for generating a laser light 3, a shutter 5 for receiving and exposing the laser light 3 from the laser light source 4 to perform exposure and non-exposure by opening and closing, and a mirror 6 for reflecting the laser light 3 from the shutter 5 are formed. A mask 11 for receiving the laser beam 3 from the shutter 5 is provided with a cutout portion or a light transmitting portion having a shape corresponding to the diffraction grating of any shape to be formed, and the diffraction grating is formed, and the cutout portion or the light transmitting portion of the mask 11 is formed. Of the planar diffraction grating forming body 7 that diffracts the laser light 3 from the light section and branches into three or more (three in this example) laser light, and the laser light branched by the diffraction grating forming body 7 , A stopper 8 which is a laser beam selecting means for passing two selected laser beams.
An image forming system 9 for forming an image of the two laser beams selected by the stopper 8 on the dry plate 1, and the movement of the XY stage 2 and the shutter 5 based on the read image data.
And a controller 10 which is a control means for respectively controlling the opening and closing of the mask 11 and the mask 11, and by making two laser beams interfere with each other, a diffraction grating is produced.

Therefore, the following various operational effects can be obtained.

(A) Since the laser light 3 is vertically incident on the diffraction grating forming body 7 serving as a beam splitter and the image forming system (lens) 9 is used as the image forming means,
Large tolerance for distortion and movement of optical system.

(B) Since the setting of the apparatus is only required to install the diffraction grating forming body 7 serving as the beam splitter and the dry plate 1 (and the XY stage 2) at the image forming position of the image forming system 9, the apparatus is set. Is extremely easy to adjust.

(C) Since the adjustment of the device is simple and the tolerance for the variation due to the distortion of the device is large, the positional accuracy of forming the diffraction grating can be remarkably improved.

(D) The device can be downsized and automated.

(E) The laser light 3 incident on the dry plate 1 is controlled by controlling the opening time of the shutter 5.
Since the exposure time to the dry plate 1 can be changed, the depth of the diffraction grating to be formed (or the density of the diffraction grating) can be changed.

(F) As the image forming means, since the image forming system 9 made of a lens which is rich in variety, easily available, and easy in cost is used, it can be carried out extremely easily.

(G) Since the liquid crystal display element which is a spatial modulation element or the like is used as the mask 11, it is possible to immediately change the shape of the diffraction grating formed every exposure.

(H) When the mask 11 is transmitted, the mask 11
By transmitting a single light flux almost perpendicularly to, it is possible to easily and automatically form a diffraction grating of any shape without causing the positional displacement as in the above-described conventional case.

(I) Since the direction of the diffraction grating to be formed can be freely selected and a spatial modulation element such as a liquid crystal display element is used as the mask 11, its shape can be made arbitrary.

From the above, the structure of the apparatus is extremely simple, the adjustment of the apparatus is also very simple, and the dry plate (photosensitive material) is used.
Diffraction gratings of any shape can be continuously manufactured accurately, easily and automatically without damaging the.

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-described embodiment, a cutout portion or a transparent portion having a shape corresponding to a diffraction grating of an arbitrary shape to be formed is provided in front of the diffraction grating forming body 7 serving as the master (on the side where the laser beam 3 is incident). Although the case of disposing the mask 11 provided with the light section has been described, the present invention is not limited to this, and the mask 11 is omitted, and instead of this, when a diffraction grating formation body to be a master is manufactured, for example, as shown in FIG. As shown, even if a diffraction grating is produced only in a preset area and is used as the diffraction grating forming body 7, the same effect as described above can be obtained. In FIG. 6, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals.

(B) In each of the above-described embodiments, the case where the opening time of the shutter 5 is controlled when the exposure is performed is described. However, the exposure is not limited to this, and the shutter is released for a preset time. 5 may be opened.

(C) In each of the embodiments described above, two lenses 91 and 92 are provided as the image forming system 9 which is the image forming means, and the focus position of the image forming system 9 exists on the surface of the dry plate 1. However, the present invention is not limited to this, and the imaging system 9 may include one lens or a plurality of lenses of three or more.

(D) In each of the above embodiments, the diffraction grating forming body 7 is attached to a rotary stage that rotates in a plane perpendicular to the optical axis of the incident laser light, and the controller is based on the read image data. By rotating by 10, the direction of the diffracted light also rotates, and therefore the angle of the diffraction grating created also changes, so that it is possible to create diffraction gratings in any direction accurately, easily, and continuously. Become.

In particular, the center of rotation does not have to coincide with the incident position of the laser beam, and the laser beam may be incident on any position of the diffraction grating forming body 7 serving as a beam splitter during rotation.
The advantage is that the equal tolerance is wide.

That is, the necessary condition is that the laser beam 3 is incident even if the diffraction grating forming body 7 serving as the beam splitter rotates, and the rotation is perpendicular to the optical axis of the laser beam 3. Only.

(E) In the embodiment of FIG. 1 described above, the mask 11 and the diffraction grating forming body 7 are attached to respective rotary stages which rotate in a plane perpendicular to the optical axis of the incident laser beam and read. The rotation of the controller 10 based on the image data also rotates the direction of the diffracted light, so that a free relationship can be established between the angle of the diffraction grating created and the angle (direction) of its shape. ..

(F) In each of the above embodiments, the case where the lenses 91 and 92 are used as the image forming system 9 as the image forming means has been described, but the present invention is not limited to this, and the holographic optical element ( HOE) may be used.

In this case, the holographic optical element is smaller and lighter than an ordinary lens or the like and can realize the same image forming function as that of the lens or the like. Can be realized.

[0090]

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 stage for moving the dry plate, and a laser beam are generated. A laser light source, a shutter that receives and emits laser light from the laser light source, performs exposure and non-exposure by opening and closing, and a cutout portion or a light-transmitting portion having a shape corresponding to a diffraction grating of any shape to be formed are provided. A mask that receives laser light from a shutter and a diffraction grating are formed, and a diffraction grating forming body that diffracts the laser light from the cutout portion or the light transmitting portion of the mask and branches it into three or more laser lights, and a diffraction grating formation Of the laser beams branched by the body, a laser beam selection unit that allows two selected predetermined laser beams to pass therethrough, and two laser beams selected by the laser beam selection unit. Since the image forming means for forming an image of the light on the dry plate and the control means for controlling the movement of the XY stage and the opening / closing of the shutter on the basis of the read data are provided, the device configuration is extremely high. It is simple and easy to adjust the equipment, and it is possible to fabricate a diffraction grating of any shape accurately and easily and automatically without damaging the dry plate (photosensitive material). A high diffraction grating plotter can be provided.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a diffraction grating plotter according to the present invention.

FIG. 2 is a main part diagram for explaining the operation in the same embodiment.

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

FIG. 4 is a schematic diagram for explaining the operation in the same embodiment.

FIG. 5 is a schematic diagram for explaining the operation in the same embodiment.

FIG. 6 is a schematic diagram showing another embodiment of the present invention.

FIG. 7 is a schematic diagram for explaining a conventional method.

[Explanation of symbols]

1 ... Dry plate, 2 ... XY stage, 3 ... Laser light, 4 ...
Laser light source, 5 ... Shutter, 6 ... Mirror, 7 ... Diffraction grating forming body, 8 ... Stopper, 9 ... Imaging system, 91, 92
... Lens, 10 ... Controller, 11 ... Mask.

Claims (13)

[Claims] 1. An apparatus for producing a dot-shaped diffraction grating by using a laser beam by the 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 X -Y stage, a laser light source for generating a laser light, a shutter for receiving and exposing the laser light from the laser light source to perform exposure and non-exposure, and a shape corresponding to an arbitrary-shaped diffraction grating to be formed A mask for receiving a laser beam from the shutter and a diffraction grating is formed, and a laser beam from the cutout portion or the light transmitting portion of the mask is diffracted to form three or more lasers. A diffraction grating forming body that branches into light, and a predetermined two laser beams selected from among the laser beams branched by the diffraction grating forming body are transmitted. A laser beam selecting unit for causing the image forming unit to image the two laser beams selected by the laser beam selecting unit on the dry plate; a movement of the XY stage based on the read data; A diffraction grating plotter, comprising: a control unit that controls opening and closing of a shutter, respectively. 2. The diffraction grating plotter according to claim 1, wherein a spatial modulation element controlled by the control means is used as the mask. 3. The diffraction grating plotter according to claim 2, wherein a liquid crystal display element is used as the spatial modulation element. 4. The diffraction grating formed body is rotated based on the read data in a plane perpendicular to the optical axis of the incident laser light. The described diffraction grating plotter. 5. The diffraction grating formation body and the mask are rotated based on the read data in a plane perpendicular to the optical axis of the incident laser light. 1. The diffraction grating plotter according to 1. 6. The diffraction grating plotter according to claim 1, wherein a lens is used as the image forming means. 7. The diffraction grating plotter according to claim 1, wherein a holographic optical element is used as the image forming means. 8. The diffraction grating plotter according to claim 1, wherein the control means controls an opening time of the shutter. 9. In an apparatus for producing a dot-shaped diffraction grating by using a laser beam by the 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 X A Y stage, a laser light source for generating a laser light, a shutter for receiving and exposing the laser light from the laser light source to perform exposure and non-exposure, and a diffraction grating is formed only in a preset region,
A diffraction grating forming body that diffracts the laser light from the shutter and splits the laser light into three or more laser lights, and passes two predetermined laser lights selected from the laser light branched by the diffraction grating forming body. A laser beam selecting unit for causing the laser beam selecting unit to form an image on the dry plate with the two laser beams selected by the laser beam selecting unit; and the movement of the XY stage based on the read data, A diffraction grating plotter, comprising: a control unit that controls opening and closing of a shutter, respectively. 10. The diffraction grating formed body is rotated based on the read data in a plane perpendicular to the optical axis of the incident laser light. The described diffraction grating plotter. 11. The diffraction grating plotter according to claim 9, wherein a lens is used as the image forming means. 12. The diffraction grating plotter according to claim 9, wherein a holographic optical element is used as the image forming means. 13. The diffraction grating plotter according to claim 9, wherein the control means controls an opening time of the shutter.