JPH07151910A - Method for exposing diffraction grating - Google Patents

Abstract

PURPOSE:To provide a method for exposing diffraction gratings capable of forming the diffraction gratings of a large size having a round number of gratings and high grating density and having no joints. CONSTITUTION:A laser beam source or mercury lamp is used as a light source for exposing and a disk-shaped recording medium 14 coated with a photosensitive agent 15 is provided. A mask 17 having single number or several pieces of radial light transmission grooves 16 varying in groove width with the positions in the radial direction of the medium is arranged on the upper part of this recording medium 14. The recording medium 14 coated with the photosensitive agent 15 is exposed with the light source for exposing from the upper part of the mask 17 while the recording medium is kept rotated exactly at the specified angle each or the recording medium 14 is exposed while the light source for exposing is flickered from the upper part of the mask 17 in compliance with the rotating action of the specified angle each of the recording medium or while the light intensity is varied, by which the high-density radial diffraction gratings are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating exposure method for forming a diffraction grating used in measuring instruments, optical rotary encoders and the like.

[0002]

2. Description of the Related Art In recent years, linear scales and encoders using a diffraction grating have been actively developed and are on the market. Various methods have been conventionally proposed as a method for producing such a diffraction grating. 10 and 11 show an example of a method for producing a diffraction grating or the like. First, Fig. 1
Reference numeral 0 indicates a configuration example of a laser trimming processing machine (laser trimmer). This is a YAG laser oscillator 1 including a pair of mirrors 1a, a Q switch 1b, an aperture 1c, a Kr arc lamp 1d, a Q switch driver 1e, etc., which face each other, a beam expander 2, and a mirror 3a.
Optical system 3 including a lens and a lens 3b, and a processing table 4
A machining table driver 5, a measuring device 6, and a computer 7 that controls each drive unit in a centralized manner. As a result, while the high-power laser beam emitted from the YAG laser oscillator 1 is focused by the lens 3b and applied to the surface of the processing material 8 placed on the processing table 4, the processing table 4 is driven by the processing table driver 5. The surface of the processing material 8 can be processed by moving it in each direction of XYZ by numerical control, and three-dimensional processing can also be performed by scanning the exposure beam.

FIG. 11 is filed by the applicant of the present invention as a "holographic recording method" in Japanese Patent Application Laid-Open No. 64-33518. This is because a pair of cylindrical lenses 12 and 13 are arranged in the irradiation light path of at least one of the reference light 10 and the object light 11 that irradiate the disk surface 9 coated with the photosensitizer, and one of the cylindrical lenses 12 and 13 is arranged. The cylindrical lens 13 is arranged such that its generatrix is inclined with respect to the generatrix of the other cylindrical lens 12. In such a state, the exposure object light 11
Is radiated in the direction connecting the generatrixes of the two cylindrical lenses 12 and 13. At this time, these two lenses 1
Since the generatrixes 2 and 13 are arranged in directions slightly different from each other, they appear as a difference in the incident angle on the disk surface 9, whereby a diffraction grating with a gradually changing grating spacing, that is, a radial diffraction grating can be created.

[0004]

In recent years, the diffraction grating has a radial shape, a cylindrical shape, a linear shape elongated in one direction, a large area, and high precision and high density. Creating a grid is becoming essential. But,
It is difficult to form such diffraction gratings of various shapes with high precision and with a good number of gratings (for example, 40,000, 100,000, etc.) by the above-described conventional manufacturing method. For example, when a long-shaped diffraction grating is created, short diffraction gratings are bonded together, but the bonding requires a high technology. In this case, there is also a method of forming the thick light flux of a huge optical system by the well-known two-beam interference method, but it requires a large lens or mirror with high surface accuracy, and the cost becomes very high. The production of a diffraction grating of 1 m or 2 m requires the world's largest optical system, which is not appropriate in terms of cost. Moreover, in such a two-beam interference method, a high-density diffraction grating can be formed, but a cylindrical diffraction grating can be formed seamlessly, or at the joints, for example, 40,000 lines can be formed accurately. It is difficult to create a good number or to bond the lattice spacing on the order of nm. Further, in the case of forming a cylindrical diffraction grating, conventionally, it is often formed by cutting, and it is difficult to form a high-density diffraction grating. In this case, the diffraction grating can be drawn with an electron beam drawing device,
This can only make a diffraction grating with an extremely small area of several mm square or less.

In addition to this, a mask for exposure is used,
There is a method of forming a diffraction grating by exposing the surface of a substrate coated with a photosensitizer placed below through a slit formed in the mask. In this case, the density of the slits that pass the light formed on the mask determines the spatial frequency, but a mask with high-density slits with a high spatial frequency should be used according to the shape of the large diffraction grating to be created by exposure. Even if an attempt is made, it is difficult and expensive to make the diffraction grating itself, and the work of transferring such a high-density diffraction grating is extremely difficult.

[0006]

According to a first aspect of the present invention, a laser light source or a mercury lamp is used as a light source for exposure, a disc-shaped recording medium coated with a photosensitizer is provided, and a groove width is provided above the recording medium. Is arranged with a mask having a single or several radial light transmission grooves that differ depending on the radial position of the medium, and the exposure light source is adjusted while accurately rotating the recording medium coated with the photosensitizer by a constant angle. By exposing from the top of the mask, or by exposing the exposure light source from the top of the mask by flashing or changing the light intensity while the recording medium is rotated by a constant angle. Thus, a high-density radial diffraction grating was created.

According to the second aspect of the invention, a laser light source or a mercury lamp is used as a light source for exposure, a linear recording medium coated with a photosensitizer is provided, and a single or several elongated light transmissions are provided on the recording medium. By arranging a mask having a groove and exposing the exposure light source from above the mask while moving the recording medium linearly in parallel at a constant distance, or by a straight line at a constant distance in the recording medium. A linear diffraction grating having a high-density linear grating array is created by flashing the exposure light source from above the mask in accordance with the movement operation or performing exposure while changing the light intensity. I did it.

In a third aspect of the invention, a laser light source or a mercury lamp is used as a light source for exposure, a cylindrical recording medium coated with a photosensitizer is provided, and one or several elongated light beams are provided on the cylindrical side surface of the recording medium. By arranging a cylindrical mask having a transmission groove and exposing the exposure light source from above the mask while accurately rotating the cylindrical recording medium by a constant angle, or a constant angle of the recording medium. A high-density cylindrical diffraction grating is created by flashing the exposure light source from the upper part of the mask in accordance with each rotating operation or performing exposure while changing the light intensity.

According to a fourth aspect of the present invention, a recording medium coated with a photosensitizer is provided, and the light intensity or focal length of the exposure beam of the exposure light source is changed on the recording medium to act on the photosensitizer. Exposure by moving the exposure beam along the lattice direction while changing the effective beam diameter, or by changing the irradiation frequency and irradiation position of the exposure beam narrowed down on the upper portion of the recording medium to obtain the desired irradiation light amount. Or the exposure light source and the condenser lens are raster-scanned on the upper part of the recording medium to raster-scan the small-focused exposure beam. By exposing while changing the intensity according to the grating arrangement, a large diffraction grating with a high density and a large shape was prepared.

[0010]

According to the first aspect of the present invention, the rotation of the recording medium or the exposure control from the upper part of the mask by using the exposure light source in accordance with the rotation is performed, so that the number of grids with good sharpness can be obtained for each rotation. It is possible to accurately form a high-density radial diffraction grating having Further, since the mask used here is formed with only a few light transmitting grooves, there is no need to form a light transmitting groove having a high spatial frequency as in the conventional case, and it is possible to make it at a lower cost than the conventional one. Become.

According to the second aspect of the invention, the linear movement operation of the recording medium or the exposure control using the exposure light source from the upper part of the mask in accordance with the linear movement operation makes it possible to obtain a good sharpness at every constant distance. It is possible to accurately fabricate a long linear diffraction grating with a high density and no joints, which has the number of gratings. Further, since the mask used here is formed with only a few light transmitting grooves, there is no need to form a light transmitting groove having a high spatial frequency as in the conventional case,
It can be produced at a lower cost than before.

According to the third aspect of the invention, the rotation operation of the recording medium or exposure control from above the mask using the exposure light source in accordance with the rotation operation is performed, whereby the number of grids with good sharpness is obtained for each rotation. It is possible to accurately manufacture a high-density and seamless cylindrical diffraction grating having Further, since the mask used here is formed with only a few light transmitting grooves, there is no need to form a light transmitting groove having a high spatial frequency as in the conventional case, and it is possible to make it at a lower cost than the conventional one. Become.

In a fourth aspect of the invention, the exposure beam from the light source for exposure is directly exposed on the surface of the recording medium while controlling the exposure, thereby performing the exposure through the mask. It is possible to accurately manufacture a large diffraction grating having a higher grating density than that of the above case. Further, this makes it possible to create a diffraction grating having a different grating pitch depending on the position, a diffraction grating having an arbitrarily complicated grating curvature, or a diffraction grating having a desired grating cross section or refractive index distribution.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention described in claim 1 is shown in FIGS.
It will be described based on. Generally, in the case of creating a diffraction grating having a number of grating arrays that are seamless and have a good interval at regular intervals, a method using only optical exposure control has, for example, a circular hologram of 40,000 per cycle. It is difficult to create in spatial frequency. On the other hand, in the method of mechanical movement control, since the movement position can be numerically controlled, it is possible to control the start and stop of the exposure device in a good place, and to arrange a grid array of a good number. It can be carried out. Further, in the conventional method of forming a mask corresponding to the entire shape of the diffraction grating to be formed to form a desired grating array, it is difficult to form the mask itself, and moreover, only such a method is very difficult. It is difficult to make a high-density diffraction grating. Therefore, in this embodiment, a mask having one or several thin light transmitting grooves is used. Then, the substrate coated with the photosensitizer is exposed, and then the substrate is moved by the distance of the grid width, or is moved by an integral multiple of the grid width and is again exposed.
Alternatively, while moving the substrate coated with the photosensitive agent at a constant speed, the exposure beam is blinked to perform the exposure, or the exposure is performed while changing the beam intensity. As a result, a high-density diffraction grating in which the number of gratings arranged at fixed intervals with no joints and good sharpness is formed is created.

A specific diffraction grating exposure method will be described below. Here, a method of forming a radial diffraction grating used in an encoder will be described. A laser light source (or a mercury lamp) is used as a light source for exposure (not shown). In FIG. 1, a hologram disk substrate 14 as a recording medium has a disc shape, and a photosensitive agent 15 is applied to the surface of the substrate. A mask 17 having a slit 16 as a light transmitting groove is arranged on the hologram disk substrate 14. This slit 16
2 (a) and 2 (b), the groove width is radially formed depending on the position of the hologram disk substrate 14 in the radial direction, and one or several (3) grooves are formed along the radial direction. Are arranged. Then, with the mask 17 having such slits 16 formed thereon being arranged on the hologram disk substrate 14 coated with the photosensitizer 15, the exposure beam 18 is emitted from the laser light source above the mask 17.
Irradiate. At this time, the hologram disc substrate 14 is accurately set to a constant angle a (corresponding to the length of one of ← in FIG. 1).
Exposure by rotating each of them, or by exposing the laser light source by periodically blinking or by changing the light intensity in accordance with the rotation operation of the hologram disc substrate 14 by a constant angle. The beam 18 passes through the slit 16 of the mask 17 and is irradiated on the photosensitive material 15 below. As a result, the radial hologram 19 having a high-density radial lattice array as shown in FIG.
(Radial diffraction grating) can be created.

As described above, the exposure is controlled from above the mask 17 using the laser light source in accordance with the rotation operation of the hologram disk substrate 14, so that the number of grids with a good sharpness (for example, 50,000) is provided for each rotation. It is possible to accurately create a high-density radial diffraction grating having 100,000 lines or the like. Further, since the mask 17 in this embodiment is formed with only one or several slits 16, it is necessary to use a mask having a high spatial frequency corresponding to the entire shape of the diffraction grating to be created as in the conventional case. As a result, the diffraction grating can be manufactured at a lower cost than before.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. The description of the same parts as those of the embodiment of the invention described in claim 1 is omitted, and the same reference numerals are used for the same parts.

In this embodiment, a method of forming a linear diffraction grating will be described. A laser light source (or a mercury lamp) is used as the light source for exposure. As the recording medium, a linear hologram substrate 20 coated with the photosensitive agent 15 is used. A mask 17 having one or several elongated slits 16 is arranged on the hologram substrate 20. In this state, the exposure beam 18 is emitted from the laser light source above the mask 17. At this time, the hologram substrate 20 is exposed while being moved in parallel linearly by a constant distance b (corresponding to the length of ← in FIG. 4) or by a constant distance of the hologram substrate 20. In accordance with the linear movement operation, the laser light source is made to blink periodically from the upper part of the mask 17 to perform exposure, or exposure is performed while changing the light intensity. Here, the hologram substrate 20 is placed at a constant distance b.
In addition to moving by one by one, by moving by the width of the grid interval,
Alternatively, when there are several slits 16, the exposure may be performed by moving the slits by several times. Further, instead of moving the hologram substrate 20, the mask 17 may be moved in the same manner. By performing the exposure in this way, it is possible to create a high-density linear diffraction grating in which gratings are arrayed at very long equal intervals.

As described above, the exposure is controlled from the upper portion of the mask 17 using the laser light source in accordance with the linear movement of the hologram substrate 20, so that the number of grids with a good sharpness and high density can be obtained at every constant distance. It is possible to accurately form a long linear diffraction grating without any joint. Further, also in the case of the present embodiment, since only one or several slits 16 are formed in the mask 17, the spatial frequency corresponding to the overall shape of the diffraction grating to be produced as in the conventional case is high. It is not necessary to use a mask and can be manufactured at low cost.

Next, an embodiment of the invention described in claim 3 will be described with reference to FIG. The description of the same parts as those of the embodiments of the invention described in claims 1 and 2 is omitted,
The same reference numerals are used for the same portions.

In this embodiment, a method of forming a cylindrical diffraction grating will be described. A laser light source (or a mercury lamp) is used as the light source for exposure. As the recording medium, a cylindrical hologram cylindrical substrate 21 coated with the photosensitive agent 15 is used. A mask 17 having one or several elongated slits 16 is arranged on the hologram cylindrical substrate 21. In this state, the exposure beam 18 is emitted from the laser light source above the mask 17. At this time, the hologram cylindrical substrate 21 having a cylindrical shape is exposed while being accurately rotated by a constant angle a (corresponding to the length of ← in FIG. 5), or the hologram cylindrical substrate 21 has a constant angle. In accordance with each rotating operation, the laser light source is periodically blinked from the upper part of the mask 17 for exposure, or exposure is performed while changing the light intensity. Thereby, a high-density cylindrical diffraction grating can be created.

As described above, the hologram cylindrical substrate 21.
The exposure is controlled by using the laser light source from the upper part of the mask 17 in accordance with the rotation operation of the above or the rotation operation of the mask 17 to obtain a high-density and seamless cylindrical diffraction grating having a good number of gratings for each rotation. Can be created accurately. Further, also in the case of the present embodiment, since only one or several slits 16 are formed in the mask 17, the spatial frequency corresponding to the overall shape of the diffraction grating to be produced as in the conventional case is high. It is not necessary to use a mask and can be manufactured at low cost.

The radial diffraction grating 19, the linear diffraction grating, and the cylindrical diffraction grating described above are formed by etching the respective exposure substrates (hologram disk substrate 14, hologram substrate 20, hologram cylindrical substrate 21). By duplicating the mold and transferring or injection-molding it from the mold to the ultraviolet curing agent, a large amount of the desired diffraction gratings can be produced inexpensively by duplication.

Next, an embodiment of the invention described in claim 4 will be described with reference to FIGS. The above-mentioned claim 1
The description of the same parts as those of the embodiments of the invention described in 3 to 3 is omitted, and the same parts are denoted by the same reference numerals.

Since the mask 17 is used in the embodiments of the invention described in claims 1 to 3, it is difficult to stably form a grating having a grating pitch of 2 μm or less due to the edge effect of the mask 17. . Further, conventionally, there is a method of directly irradiating a mechanical component with a laser beam to form it by laser processing, but this method directly melts a metal, and ultrafine processing accuracy cannot be expected. Therefore, in this embodiment, as shown in FIG.
As shown in FIG. 3, the exposure beam 13 (laser light) emitted from the laser light source 22 as an exposure light source is condensed through a lens 24 without using a mask to obtain a recording medium coated with the photosensitizer 15. The surface of the substrate 25 is directly exposed and developed. Arrows x and y in FIG.
Indicates the amount of displacement of the substrate 25 per time. Such a manufacturing method is not performed by an electron beam drawing apparatus in the air like a semiconductor process, but is performed by exposing the photosensitive agent 15 to light while moving a laser beam in the air. This makes it possible to create a diffraction grating having a much larger shape (here, referred to as a large diffraction grating), unlike the case where the diffraction grating is created by the electron beam drawing method. Moreover, such a manufacturing method does not require adhesion to the substrate 25 as when using a mask, and thus the substrate 2
Since it is possible to perform exposure with the light source 5 and the light source section kept separated, it becomes very easy in terms of scannability.

A specific diffraction grating exposure method will be described below with reference to FIGS.
It will be described with reference to FIG. First, FIG. 7 is an example of a case of forming a radial diffraction grating. When creating this radial diffraction grating, the spatial frequency is different between the circumferential side P and the central side Q in the radial direction r on the disk surface that is the substrate 25. Therefore, from such a fact, the relative position between the laser light source 22 and the substrate 25, the light intensity and the focal length of the exposure beam 23 are changed by moving the lens 24, and thereby the photosensitive agent 15 is substantially affected. The exposure beam 23 is moved along the desired lattice direction while changing the beam diameter. This makes it possible to create a large-diameter diffraction grating having a different width depending on the position (inner circumference), for example, a diffraction grating having a different grating pitch depending on the position.

Further, in the case where a blazed grating whose diffraction efficiency is increased depending on the incident angle is created, the irradiation number and the irradiation position of the exposure beam 23 narrowed down by the lens 24 are changed to change the irradiation light amount to a desired grating shape. Exposure so that the distribution becomes. As a result, as shown in FIG. 8, a large-shaped diffraction grating 26 having a sawtooth cross section can be formed. In this case, the position m indicates the position of the large number of exposure lines where the irradiation number is large, and the position n indicates the position of the small number of exposure lines where the irradiation number is small. The cross-sectional shape shows the cross-sectional shape of the etched lattice after exposure.

In the exposure method shown in FIGS. 7 and 8, the condensed exposure beam 23 is moved in the grating direction. However, it is difficult to create a more complicated grid shape by such a method. Therefore, the laser light source 22 and the lens 24 (condenser lens) are raster-scanned, and the exposure beam 23 condensed by this is raster-scanned to perform exposure while changing the light intensity of the exposure beam 23 in a blinking manner according to the lattice arrangement. As a result, a large diffraction grating 27 having a complicated grating shape and direction as shown in FIG. 9 can be created. The diffraction grating 27 has a locus 28 of raster scanning lines of the exposure beam 23 which meanders in an oblique direction, thereby forming a complicated grating pattern that traverses vertically and horizontally.

As described above, in the case of the invention according to any one of claims 1 to 3, the exposure beam 23 from the laser light source 22 is exposed through the mask 17 by directly exposing the surface of the substrate 25 while controlling the exposure. It is possible to accurately manufacture a large diffraction grating having a higher grating density. Further, since the exposure beam 23 can be freely scanned in the air, a diffraction grating having a different grating pitch depending on the position, a diffraction grating having an arbitrarily complicated curvature of the grating, a desired grating section or a refractive index distribution can be obtained. Diffraction gratings of various shapes, such as a diffraction grating having the same, can be easily created.

[0030]

According to the first aspect of the present invention, a disc-shaped recording medium coated with a photosensitizer is provided by using a laser light source or a mercury lamp as a light source for exposure, and a groove width of the medium is provided above the recording medium. A mask having a single or several radial light transmitting grooves that differ depending on the position in the radial direction is arranged, and the exposure light source is placed above the mask while accurately rotating the recording medium coated with the photosensitizer by a predetermined angle. From the top of the mask by exposing the light source for exposure from the top of the mask in accordance with the rotation operation of the recording medium at a constant angle, or by changing the light intensity. Since a large radial diffraction grating is created, it is possible to accurately create a high-density radial diffraction grating having a good number of gratings for each rotation of the recording medium. Moreover, since only a few light transmitting grooves are formed in the mask, it is not necessary to form a light transmitting groove having a high spatial frequency, and an inexpensive exposure method can be provided.

According to a second aspect of the present invention, a laser light source or a mercury lamp is used as an exposure light source, a linear recording medium coated with a photosensitizer is provided, and one or several elongated light transmissions are provided on the recording medium. By arranging a mask having a groove and exposing the exposure light source from above the mask while moving the recording medium linearly in parallel at a constant distance, or by a straight line at a constant distance in the recording medium. A linear diffraction grating having a high-density linear grating array is created by flashing the exposure light source from above the mask in accordance with the movement operation or performing exposure while changing the light intensity. Since this is done, it is possible to accurately form a long linear diffraction grating with a high density and a good number of gratings for every constant distance of the recording medium. Moreover, since only a few light transmitting grooves are formed in the mask, it is not necessary to form a light transmitting groove having a high spatial frequency, and an inexpensive exposure method can be provided.

According to a third aspect of the present invention, a laser light source or a mercury lamp is used as an exposure light source, a cylindrical recording medium coated with a photosensitizer is provided, and one or several elongated light beams are provided on the cylindrical side surface of the recording medium. By arranging a cylindrical mask having a transmission groove and exposing the exposure light source from above the mask while accurately rotating the cylindrical recording medium by a constant angle, or a constant angle of the recording medium. In order to create a high-density cylindrical diffraction grating, the exposure light source is blinked from the upper part of the mask in accordance with each rotating operation to perform exposure, or the exposure is performed while changing the light intensity. It is possible to accurately produce a high-density and seamless cylindrical diffraction grating having a sharp number of gratings for each rotation of the medium. Moreover, since only a few light transmitting grooves are formed in the mask, it is not necessary to form a light transmitting groove having a high spatial frequency, and an inexpensive exposure method can be provided.

According to a fourth aspect of the present invention, a recording medium coated with a photosensitizer is provided, and the light intensity or the focal length of the exposure beam of the exposure light source is changed above the recording medium to act on the photosensitizer. Exposure by moving the exposure beam along the lattice direction while changing the effective beam diameter, or by changing the irradiation frequency and irradiation position of the exposure beam narrowed down on the upper portion of the recording medium to obtain the desired irradiation light amount. Or the exposure light source and the condenser lens are raster-scanned on the upper part of the recording medium to raster-scan the small-focused exposure beam. By exposing while changing the intensity according to the grating arrangement, a large diffraction grating with a high density and a large shape is created. Therefore, the grating density is higher and the size is larger than when using a mask. The diffraction grating can be made accurately. Since the exposure beam can be freely scanned in the air, it has a diffraction grating with a different grating pitch depending on the position, a diffraction grating with an arbitrarily complicated curvature of the grating, or a desired grating cross section or refractive index distribution. Diffraction gratings of various shapes such as a diffraction grating can be created.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method of exposing a radial diffraction grating which is an embodiment of the invention described in claim 1.

FIG. 2 is a view showing a slit shape formed on a mask, (a) is a front view in the case of having one slit,
(B) is a front view in the case of having three slits.

FIG. 3 is a front view of a radial diffraction grating.

FIG. 4 is a perspective view showing an exposure method of a linear diffraction grating which is an embodiment of the invention according to claim 2;

FIG. 5 is a perspective view showing an exposure method of a cylindrical diffraction grating which is an embodiment of the invention as set forth in claim 3;

FIG. 6 is a perspective view showing a method of exposing a large diffraction grating which is an embodiment of the invention described in claim 4;

FIG. 7 is a perspective view showing an exposure method in the case of forming a radial diffraction grating.

FIG. 8 is a schematic diagram showing a state in which a diffraction grating having a sawtooth cross-sectional shape is drawn in a simulated manner.

FIG. 9 is a perspective view showing a state of a diffraction grating having a complicated grating pattern by raster scanning.

FIG. 10 is a configuration diagram showing a conventional laser trimming processing machine.

FIG. 11 is a front view showing a conventional recording method of a diffraction grating.

[Explanation of symbols]

 14 Recording Medium 15 Photosensitizer 16 Light Transmission Groove 17 Mask 18 Exposure Beam 19 Radial Diffraction Grating 20, 21 Recording Medium 22 Exposure Light Source 23 Exposure Beam 24 Condensing Lens 25 Recording Medium

Claims (4)

[Claims] 1. A disc-shaped recording medium coated with a photosensitizer is provided by using a laser light source or a mercury lamp as a light source for exposure,
A mask having a single or several radial light transmitting grooves whose groove width differs depending on the radial position of the medium is arranged on the upper part of the recording medium, and the recording medium coated with the photosensitizer is accurately set at a constant angle. By exposing the light source for exposure from above the mask while rotating, or by exposing the light source for exposure by blinking from above the mask in accordance with the rotation operation of the recording medium at a constant angle. A diffraction grating exposure method characterized by forming a high-density radial diffraction grating by exposing while changing the light intensity. 2. A linear recording medium coated with a photosensitizer is provided by using a laser light source or a mercury lamp as a light source for exposure,
A mask having one or several elongated light transmitting grooves is arranged on the upper portion of the recording medium, and the light source for exposure is exposed from the upper portion of the mask while the recording medium is moved linearly in parallel at a constant distance. Or by exposing the exposure light source by flashing from the upper part of the mask in accordance with the linear movement operation of the recording medium by a constant distance, or exposing while changing the light intensity. A method for exposing a diffraction grating, which comprises forming a linear diffraction grating having a long grating array. 3. A cylindrical recording medium coated with a photosensitizer is provided by using a laser light source or a mercury lamp as a light source for exposure.
A cylindrical mask having one or several elongated light transmitting grooves is arranged on the cylindrical side surface of this recording medium, and the exposure light source is placed above the mask while accurately rotating the cylindrical recording medium by a predetermined angle. By exposing from
A high-density cylindrical diffraction grating is created by flashing the exposure light source from the upper part of the mask in accordance with the rotation operation of the recording medium at a constant angle or by exposing while changing the light intensity. A diffraction grating exposure method characterized by the above. 4. A recording medium coated with a photosensitizer is provided, and the substantial beam diameter acting on the photosensitizer is changed by changing the light intensity or the focal length of the exposure beam of the exposure light source above the recording medium. While moving the exposure beam along the lattice direction for exposure, or changing the irradiation frequency and irradiation position of the exposure beam narrowed down on the upper part of the recording medium, the distribution of the irradiation light quantity is a desired lattice shape distribution. Or the exposure light source and the condenser lens are raster-scanned on the upper part of the recording medium to raster-scan the small-focused exposure beam and change the light intensity according to the lattice arrangement. A diffraction grating exposure method characterized in that a large diffraction grating having a high density and a large shape is created by performing exposure while performing the exposure.