JPH0658588B2 - Original image capturing method for flat type holographic stereogram - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing a rainbow hologram from a flat holographic stereogram, in which a camera is moved along a straight line when a series of original images are taken. In addition, by rotating the lens, the lens always moves so that it faces the direction of the subject, and although there is some distortion, it expands the viewing range that was previously limited to shooting with linear movement, and it is possible to shoot nearby. Therefore, the present invention relates to a technique for producing an original image with detailed resolution.

<Prior Art> A method for producing a rainbow hologram from a planar holographic stereogram, and an experimental report based on the method are described in M. et al. C. King, A .; M. No. 11, D.I. H.
Berry et al., Appl. Opt. Vol 19
No. 2 471 (1970). In their experiments, one frame of a series of images taken by a camera was projected on a diffuser plate to make small holograms one by one. We are making holograms that can be reproduced with light. There is another method for producing the master hologram shown in this method, and a report on a method for producing a holographic stereogram by Mr. Kasahara and others of Konishi Roku Photo Co., Ltd. Proc, U. S. −
Japan Seminar On Infomatic
on Processing By Holograp
hy (Oct. 1969) 19, Plenum Pr
ess (1971) New-York-London, Japanese Patent Publication No. 47-44656, Japanese Patent Publication No. 49-5258. Briefly, a method of producing a flat holographic stereogram and a method of producing a rainbow hologram using the same will be described by one of the methods in this patent. First, as shown in FIG. The object (1) is photographed while moving by d. In this way, an image having a series of parallaxes is obtained. A positive original image is prepared from this image.

FIG. 4 shows an optical system for producing a planar holographic stereogram from this original image (22). FIG. 4 (a) is a view of the optical system seen from above, and FIG. 4 (b) is a view seen from the side. The light emitted from the laser (10) is split into two by the half mirror (12), and the light (40) passing through the half mirror (12) is reflected by the mirror (1
4) It is guided to the lens (18) by (16), passes through the lens (20) and illuminates one frame of the original image (22), and the lens (24) displays it on the screen (26). After passing through the screen (26), it is diffused and a part of the image passes through the small aperture (28) to reach the hologram dry plate (30).

On the other hand, the light (42) reflected by the half mirror is
After passing through 2) and (34), the light is collimated by the lenses (36) and (38) and reaches the hologram dry plate (30) after passing through the small aperture (28). The two divided lights (40) and (42) form interference fringes on the hologram dry plate (30) and record them. Next is the original picture
(22) is fed one frame, and a small aperture is sent along the hologram dry plate a little according to the condition that the original image was photographed, and the interference fringe is recorded again. By repeating this operation, a flat holographic stereogram is produced.

When parallel light (52) is incident on the plane type multiplex hologram synthesized in this way as shown in FIG.
A reproduced image appears where the screen was placed. A new hologram dry plate (48) is placed at this position and the reference beam (5
A rainbow hologram can be produced by making (0) incident and forming interference fringes and recording the interference fringes.

<Problems to be Solved by the Invention> In the original image shooting shown in FIG. 3, since the camera moves along a straight line, if the camera moves to a certain extent as the shooting progresses, the subject will be out of the field of view of the lens. It will not be reflected in the image. For this reason, a flat holographic image created from the original image obtained in this way
The stereogram has a limited visual field, which is one of the drawbacks when it is used for a display or the like. Therefore,
It is possible to use a wide-angle lens to avoid this, but this time, the distortion peculiar to the wide-angle lens is generated in the periphery of the film, and it becomes difficult to obtain an original image in which fine details of the object are finely resolved. .

<Means for Solving Problems> FIG. 1 shows an original image photographing method of the present invention. The present invention is an improvement over the conventional method in which the camera (62) is aligned (6
When moving 6), rotate it little by little so that it always faces the center (65) of the subject (61).

If such a shooting method is adopted, as long as the field of view of the lens (63) is relaxed, it is possible to shoot in close proximity, so that it is possible to resolve fine details and obtain a wide viewing angle (67). become.

However, at this time, since the camera is always looking at the center of the subject, the magnification slightly changes in the direction of the viewing zone, that is, the direction of the line of eyes, which causes distortion when a flat holographic stereogram is created. 2 will occur, but the degree thereof is slight, which will be explained with reference to FIG.

FIG. 2 shows that the object is on the y-axis with O as the center, and the camera is translated to the y-axis at a position away from it by a on the x-axis,
And when it is always facing O, the point y on the y-axis
_{A value of 0} indicates that the length is changed because the image captured at y ₁ when the camera is not rotated is imaged at the point A ′ due to the rotation. In other words, ▲ ▼ ₁ is ▲
▼, and the ratio of the lengths is the strain rate. If the distortion rate at this time is R Becomes Where θ is the angle the camera makes with the x-axis, a is the distance from the object, and y ₀ is the size of the object. Applying the actual shooting conditions to this equation, a = 12
When calculated with 00 mm and Y ₀ of 200 mm, R at θ = 14 °
= 0.9θ = 20 °, R = 0.83. It becomes small like this and is photographed.

This means that the reconstructed image that can be seen from what is combined with the planar multiplex hologram will become smaller as it deviates from the center, the parallax direction, which is smaller on the lines that squint both eyes, and it will appear to be slightly retracted in the back. . However, it is not a problem because the degree is small and the appearance is natural. Also, 35
When a focal length of 55 mm is attached with a mm camera, a = 1200
The size of the object that can be photographed in mm is ± 350 mm.
Now, if there is an object of ± 200 mm, it can only move ± 150 mm, and this angle is ± 7 °. This also proves that the method shown here is effective.

<Example> An example of producing a rainbow hologram on a photoresist will be described. An Ar laser was used as the laser, and the original image with continuous parallax was obtained by shooting according to the program by installing the camera on the stage under the computer control that can be moved and rotated according to FIG. It was

The hologram plate has 8E56 from Agfa-Gevaert.
HD is used, and the diffusion plate is ground glass,
A plane type multiplex hologram was produced by the optical system shown in FIG.

Next, this plane type holographic stereogram was placed in the optical system shown in FIG. 5, and a rainbow hologram was prepared using AZ-1350 photoresist of Supre-Ferist as a hologram dry plate.

<Advantages of the Invention> Conventionally, since there is a limit to the size of an object that can be made into a rainbow hologram, a flat holographic stereogram as shown here has been used to overcome this limitation. However, the present invention has a limited field of view and is a problem when used for a display. However, the present invention removes this field of view limitation, has a sufficiently wide field of view, and a reproduced image of a hologram with a sufficient resolution. It is industrially effective in the field of display because it is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a photographing method of the present invention, and FIG. 2 is an explanatory diagram for explaining distortion. Also, FIG. 3 and FIG.
5 and 5 are explanatory views showing a conventional photographing method.
(A) and (b) of the figure are a top view and a side view, respectively. (1) …… Object, (2) …… Camera (3) …… Lens, (4) …… Film (10) …… Laser, (12) …… Half mirror (14) …… Half mirror (16) …… Mirror, (18) …… Lens, (20) …… Lens (22) …… Original image, (24) …… Lens (26) …… Diffuser, (28) …… Small aperture (30) …… Hologram plate, (32) …… Mirror (34) …… Mirror, (36) …… Lens (38) …… Lens, (40) …… Light flux (42) …… Light flux, (44) …… Diffused light ( 46) …… Diffused light, (48) …… Hologram dry plate (50) …… Reference light, (52) …… Parallel light (54) …… Plane multiplex hologram (61) …… Subject, (62)… … Camera (63) …… Lens, (64) …… Film (65) …… Center point, (66) …… Straight line (67) …… Viewing angle

Claims (1)

[Claims] 1. A method for producing a large number of original images having a continuous parallax with a camera or the like, synthesizing a planar holographic stereogram from the original images, and further producing a rainbow hologram from the planar holographic stereogram. In the above, in the original image shooting method, the original image shooting method for a flat holographic stereogram is characterized in that the camera is rotated while moving on a straight line so that the lens always faces the direction of the subject.