JPH0320723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that sequentially exposes a photosensitive film by changing the pitch and light intensity of minute interference fringes caused by two-beam interference, and after exposure, the film is developed. By doing so, a pattern formed by a diffraction grating can be obtained.

Conventionally, masks made of photographic film or paper have been used to obtain patterns using diffraction gratings, and in order to obtain patterns using many diffraction gratings, many masks are required, and the pitch of the diffraction gratings, Changing the diffraction efficiency requires a huge amount of effort and time, and currently many patterns using diffraction gratings are not available. The present invention eliminates this drawback and is an apparatus that makes it possible to obtain a diffraction pattern in which the pitch of the diffraction grating and the diffraction efficiency are changed freely and continuously, and it is possible to obtain new images never seen before. That is, the present invention is an apparatus comprising at least a movable document rack for setting a photosensitive film, and a movable exposure head for exposing interference fringes generated by two-beam interference on the photosensitive film. The exposure head includes a shutter for blocking the light incident thereon as necessary, a half mirror for dividing the light passing through the shutter into two beams, and a double beam divided by the half mirror. The half mirror is configured to guide each of the two light fluxes to each of a pair of lens systems having the same configuration via a rotating mirror, and to condense each light flux that has passed through each of the lens systems at one point;
A diffraction grating exposure apparatus is characterized in that a rotating mirror and a lens system are each disposed within a fixed block.

The present invention will be described below with reference to the schematic diagrams of the apparatus shown in FIGS. 1 and 2. FIG. 1 shows the main parts of this device.
A drum 2 to which it is attached and rotates, a pulse motor 3 to rotate it, a rotary encoder 1 to detect rotation, an exposure head 5 to expose the photosensitive film, a guide 6 to stably hold and move it, a ball screw 8, This device is composed of a pulse motor 9, a rotary encoder 7, a laser beam oscillator (not shown), and the like. A laser beam 4 for exposure enters an exposure head 5, exits through a small window 11, and reaches a photosensitive film 10. FIG. 2 shows the inside of the exposure head 5. As shown in FIG.
The exposure head 5 has lenses 18, 19, 20, 21,
Mirror 12, 15, 16, 17, half mirror 1
4, a shutter 22, and a block 23 that supports them. laser beam 4
passes through the shutter 22 and the mirror 12, and is divided into two beams by the half mirror 14. One beam passes through the rotating mirror 16 and lenses 18 and 19 and reaches the small window 11, and the other beam passes through the rotating mirror 1
7. Reaches the small window 11 through the lenses 20 and 21,
Interference fringes due to the two light beams are formed at the small window 11. In this optical system, rotating mirrors 16, 17
is placed at a focal length f ₁ of lenses 18 and 20, and the light reflected by these rotating mirrors 16 and 17 is reflected by lenses 18 and 20.
After passing through, the light becomes parallel to the optical axis. When this parallel light beam enters the lenses 19 and 21, it converges at the focal length f ₂ of each lens 19 and 21.
Therefore, although the direction of the light changes by rotating the rotary mirrors 16 and 17, the two light beams always intersect at the same location, that is, at the small window 11. The pitch d of the interference fringes created at this time is
It is given by the following formula.

d=λ/sin Θ ₁ −sin _{Θ 2} (1) where λ is the wavelength of the laser, and Θ ₁ and Θ ₂ are the angles that the two light beams make with the normal direction of the small window 11. In FIG. 1, Θ ₂ is a negative value.

Photosensitive film 10 patterned by this device
For example, the angle of the two light beams (Θ ₁
+Θ ₂ ) and the opening/closing time of the shutter 22.

In this case, first, an original image to be converted into a diffraction grating is set in a scanner, and the pitch of interference fringes is arbitrarily determined based on red, green, and blue color signals obtained through a scanning head, a photoelectric conversion element, etc. Next, the rotating mirrors 16 and 17 are rotated so that the determined pitch can be set on the photosensitive film 10, and the small window 1
The angle (Θ ₁ + Θ ₂ ) of the two beams entering 1 is changed.
Next, the opening/closing time of the shutter 22 is determined in accordance with the optical density obtained from the original image set in the scanner, and exposure is performed. The diffraction efficiency of the diffraction grating can be changed by changing the exposure time. By repeating this series of operations for each pixel, it is possible to create an image using a diffraction grating from the original image.

When white light such as that from the sun is incident on a pattern made of a diffraction grating created in this way, colors with different brightness can be seen due to differences in the pitch and diffraction efficiency of the diffraction grating in each part of the pattern, and the overall You can see a pattern that shines in seven colors like crimson.

Thanks to the invention of this device, the present invention has the above-described configuration, so it is possible to quickly and easily draw a picture with a diffraction grating while freely changing the pitch and diffraction efficiency of the diffraction grating without using a mask. It can be used in the display field and is industrially effective.

Although the present invention has been described using an example in which a drum-shaped document shelf is used, the present invention is not limited thereto. It may be a device of configuration. Furthermore, using the device according to the invention,
Instead of creating a diffraction grating pattern based on a signal from a scanner, it is also possible to create a diffraction grating pattern by directly outputting an original image created by a computer to a printer.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of the main parts of this apparatus, and FIG. 2 is an explanatory diagram showing the inside of the exposure head. 1, 7... Rotary encoder, 2... Drum, 3, 9... Pulse motor, 4... Laser beam, 5... Exposure head, 8... Ball screw, 10... Photosensitive film, 11... Small window, 12... Mirror, 14
... Half mirror, 15... Mirror, 16, 17... Rotating mirror, 18, 19, 20, 21... Lens, 2
2...Shutter, 23...Support block.

Claims (1)

[Claims] 1. A device comprising at least a movable document rack for setting a photosensitive film, and a movable exposure head for exposing interference fringes generated by two-beam interference on the photosensitive film, and the exposure head includes a shutter for blocking the light incident on it as necessary, and a half mirror for splitting the light passing through the shutter into two beams.
Each of the two light beams divided by the half mirror is guided to each of a pair of lens systems of the same configuration via a rotating mirror, and each light beam that has passed through each lens system is directed to a single point. A diffraction grating exposure apparatus characterized in that each of the half mirror, rotating mirror and lens system is arranged within a fixed block so as to condense light.