JPH0458631B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for producing a rainbow hologram from a planar holographic stereogram, in which a camera is moved in a straight line when photographing a series of original images. By adding rotation,
Always move the lens so that it faces the subject,
Furthermore, when creating a positive original picture from this negative,
By applying the bias distortion correction technology used in aerial photography, etc., it is possible to expand the field of view, which was limited by conventional straight-line movement photography, and to take close-up photographs without distortion. , relates to technology for producing original images that are resolved down to the smallest detail.

<Prior art> A method for producing a rainbow hologram from a planar holographic stereogram and an experimental report based on it are published in MCKing, AM No. 11, DH
Appl.Opt.Vol 19 No.2471 by Berry et al.
(1970). In their experiment, one frame of a series of images taken by a camera was taken on a diffuser plate to create each small hologram, and each hologram created in this way was used as a master hologram. , has created a hologram that can be reproduced using white light. The method of making a master hologram shown in this method is as follows:
In addition, Mr. Kasahara of Konishiroku Photo Industry Co., Ltd. and others reported a method for making holographic stereograms.Proc.US-Japan Seminar On
Information Processing Byz Holography
(Oct, 1969) 19, Plenum Press (1971) New−
York-London, Special Publication 47-44656, Special Publication 1977-
5258. To briefly describe a method for producing a planar holographic stereogram and a method for producing a rainbow hologram using the method described in this patent, first, as shown in Fig. 3, the camera 2 is moved by d. While doing so, photograph object 1. In this way, a series of images with parallax are obtained. A positive original image is created from this image.

An optical system for producing a planar holographic stereogram from this original image 22 is shown in FIG.
FIG. 4a is a view of the optical system viewed from above, and FIG. 4b is a view of the optical system viewed from the side. The light emitted from the laser 10 is split into two by a half mirror 12.
The light 40 that has passed through the lens 2 is guided to the lens 18 by the mirrors 14 and 16, passes through the lens 20, illuminates one frame of the original image 22, and is displayed on the screen 26 by the lens 24. After forming an image and passing through the screen 26 , it is diffused and a portion of it passes through the small aperture 28 and reaches the hologram dry plate 30 .

On the other hand, the light 42 reflected by the half mirror passes through the mirrors 32 and 34, becomes parallel light by the lenses 36 and 38, and reaches the hologram dry plate 30 after passing through the small aperture 28. These two divided lights 40 and 42 create interference fringes on the hologram dry plate 30, which are recorded. Next, the original image 22 is advanced one frame, and the small aperture is set according to the conditions under which the original image was photographed.
It is sent a short distance along the hologram plate and records interference fringes again. By repeating this operation, a planar holographic stereogram is produced.

As shown in Fig. 5, parallel light 5
2, a reproduced image appears where the screen was placed. A new hologram dry plate 48 is placed at this position, the reference beam 50 is made incident,
A rainbow hologram can be created by creating interference fringes and recording the interference fringes.

<Problems to be Solved by the Invention> During the original image shooting shown in Figure 3, the camera moves in a straight line, so as the shooting progresses, if the camera moves to a certain extent, the subject will be out of the field of view of the lens. The image becomes blurred and becomes blurry. For this reason, a planar holographic stereogram made from the original image obtained in this manner has a limited viewing range, which is a drawback when used for a display or the like. Therefore, it is possible to use a wide-angle lens to avoid this problem, but this will cause distortion peculiar to wide-angle lenses around the film, and it will be difficult to obtain clear resolution of the details of the object. I end up.

<Means for Solving the Problems> FIG. 1 shows the principle photographing method of the present invention. The present invention is an improvement over the conventional method, in which the camera 62
rotates slightly as it moves along a straight line 66 so that it always faces approximately the center 65 of the subject 61. If such a photographing method is adopted, the photograph can be taken as close as the field of view of the lens 63 allows, so that sufficiently fine details can be resolved and a sufficiently wide viewing angle 67 can be obtained.

However, since the camera is always looking at the center of the subject, the magnification changes slightly in the direction of the viewing area, that is, in the direction of the eye alignment. Corrections are made when creating a positive image of an image that looks like it was taken while moving the camera. This method is a bias correction method used when converting an oblique photograph to a vertical photograph in aerial photography. Figure 2a shows subject 7 taken using the photographing method shown in Figure 1.
Points on film 68 and special points on film 68 are shown. However, here, the subject 70 is assumed to be a plane.

S is the position of the lens, where the subject 70 and the film 6
Each point on 8 has a projective relationship with S as the center.

To explain the special points shown in this figure, the point P where the line connecting the lens S and the photographic principal point p intersects the subject plane 70 is N, and the point perpendicular to the subject plane 70 from S is N, and the corresponding film Let the point on the plane 68 be n, the point where the line that bisects the NSP intersects with the subject 70 be J, and the point where it intersects with the film 68 be j.
Under such a relationship, point A on the straight line NP is projected onto point a on the film 68, and considering the magnification at that time, it is given by the equation M'=f/l (1). f is the focal length of the lens, and l is the photographing distance to point A. Now, if ∠NSA=ω, then l=f/SACOS(ω-ν)...2 equations are obtained. Substituting this into equation (1) yields M'=f/SA COS (ω-ν)...Equation (3). Here, =SN/COSω...Using equation (4), M'=f COSω/SN COS(ω-ν)...(5) equation is obtained.

Here, considering the magnification for vertical photography, the magnification M at that time is given by the equation (6): M=f/SN.

Than this M'=MCOSω/COS(ω-ν)...Equation (7) becomes.

Considering this equation, at the point where ω=ν, that is, at point P, M'=MCOSν, and at point J, ω=ν/2, so M'=M. In other words, only point J has the same magnification as when shooting vertically. Now, FIG. 2b shows a method for correcting images that are taken at different magnifications in each part.

A negative 72 photographed and developed using the method shown in FIG. 1 is placed 2f from a lens 74 having a focal length f. Furthermore, place film 76, which will be a positive, at a distance of 2F. This system is a 1:1 projection system. In this system, by tilting the image by an angle ν and then tilting it in the opposite direction by an angle ν,
It is possible to return to M′=M.

In other words, you can go from tilted photography back to vertical photography. At this time, care must be taken to ensure that point i is always at the center of rotation.

Next, we will show that it is possible to return to M'=M. In Figure 2a, point J is the origin of the subject, point j is the origin on the film 68, and the coordinates of point A are (0, Y').
Let the coordinates of point a be (0, y'). Further, when SN=H, the relationship between Y' and y' is given by Y'=y'H/f-y'sinν (8).

Now, in b of FIG. 2, the negative film 72
If the length to point 80 at a certain distance from the center of rotation above is y'', then by correcting the biased distortion, point 80
is projected onto the point 84 and the distance from the positive center of rotation 82 becomes y', then the relationship between y' and y'' is given by y' = y''f/f + y''sinν - equation (9). Substituting this into equation (8) yields Y′=y″H/f ……(10).

This is the coordinate relationship for vertical photography, and the magnification is the same everywhere, that is, M=const.

Next, we will show the effectiveness of this method using concrete numbers.

Using the conventional method, using a 35mm camera with a 55mm focal length lens, the object size that can be photographed at 1200mm from the subject is ±350mm. Now, if there is an object that is ±200mm, the camera can only move ±150mm, which is expressed as an angle of ±7°.

If the method proposed here is used, theoretically it will be ±∞, that is, ±90°, but in reality, it will be limited in the correction of biased distortion. Currently, the eccentric distortion corrector currently in use, such as the Zeiss SEG-V model, is capable of correction up to 16°. Even compared to this figure, it can be seen that the viewing area is expanded by more than twice as much.

<Example> An example of producing a rainbow hologram on a photoresist will be described. For the laser
An original image with continuous parallax using an Ar laser was obtained by setting up a camera on a computer-controlled stage that could move and rotate as shown in Figure 1, and taking pictures according to the program. .

The biased distortion was corrected by using a self-made rotary stage and changing the rotation angle for each frame.

The hologram plate was made by Agfa Gewald.
A planar holographic stereogram was created using the optical system shown in FIG. 4 using an 8E56HD and a ground glass diffuser.

Next, this planar holographic stereogram was placed in the optical system shown in FIG.
A rainbow hologram was created using 1350 photoresist.

<Effects of the Invention> Conventionally, there is a limit to the size of an object that can be made into a rainbow hologram, and attempts have been made to overcome this limit by using a flat holographic stereogram as shown here. The field of view was limited, which was a problem when used in displays, but with the present invention, this field of view limitation has been removed. Since a reproduced image can be obtained, this method is industrially effective in the display field.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the photographing method of the present invention, and FIG. 2 is an explanatory diagram for explaining distortion (and distortion correction). In addition, Figs. 3, 4, and 5 are explanatory diagrams showing the conventional photographing method, and a and b in Figs.
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 picture, 24... Lens, 26... Diffusion plate, 28...
...Small aperture, 30...Hologram dry 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...
...Planar multiplex hologram, 61...
Subject, 62...Camera, 63...Lens, 64
... Film, 65 ... Center point, 66 ... Straight line, 67 ... Viewing angle, 68 ... Film, 70 ...
Subject, 72... Negative film, 74... Lens, 76... Positive film, 78... Center of rotation,
80...Arbitrary point on the negative film, 82...Rotation center, 84...Point corresponding to 80.

Claims (1)

[Claims] 1. A method in which a large number of original images with parallax are continuously produced using a camera, etc., a planar holographic stereogram is synthesized from these original images, and a rainbow hologram is further produced from this planar holographic stereogram, A planar hologram that is characterized by the fact that when taking an original image, the camera is rotated while moving in a straight line so that the lens is always facing the subject, and then the biased distortion is corrected when converting it to a positive original image. How to expand the visual field of a stereogram.