JPH01124887A - Synthetic hologram recording method for observation of stereoscopic image - Google Patents

Abstract

PURPOSE:To shorten the time for recording by executing recording by using the direction image of an object converted by an incoherent-coherent image converting element as an input image. CONSTITUTION:The object 1 is illuminated by incoherent light 20 and the image thereof is imaged by a photographing lens 2 to the input face of the incoherent- coherent image converting element 3. The output face of the incoherent-coherent image converting element 3 is illuminated by laser light past a beam expander 5 and a half mirror 6 so that the coherent image light is reflected by a half mirror 6 and is formed on a diffusion screen 7 by a projecting lens 14. Element holograms are then successively recorded via a moving slit 8 on a hologram photosensitive material 9. The direct image of the object converted by the incoherent-coherent image converting element is used in such a manner in place of the film image used heretofore as the input image and, therefore, the need for making two-stage photographing is eliminated and the time for development processing of the film is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to JIil!, a composite hologram for stereoscopic image observation in which a large number of elemental holograms such as holographic stereograms and multiplex holograms are arranged in parallel. How to record and open.

[Prior Art] Holographic stereograms and multiplex holograms, which are improved versions of holographic stereograms, are conventional holographic techniques used to record and display a three-dimensional image of an object illuminated by incoherent light. Published by Japan Optomechatronics Association, “Optical Applied Machinery Industrial Technical Staff Training Course Text, Optical Applied Technology 1987 Edition, n-
1. Optics (2) Wave optics”).

A conventional method for creating a holographic stereogram will be explained using FIGS. 4 and 5.

FIG. 4 is an explanatory diagram of a conventional holographic stereogram input image recording method, and FIG. 5 is a horizontal sectional view (a) and a vertical sectional view (b) of a conventional holographic stereogram recording apparatus.

In the first stage, as shown in FIG. 4, a picture of the object l is taken every time the camera lO is moved horizontally by d, and pictures with parallax in the horizontal direction are taken one after another. Of course, in this case, it is not necessary to illuminate the object l with coherent light such as a laser beam.In the second step shown in FIG. 5, the photographic film 11 taken in the first step is reversed to positive,
A laser beam 1 is transmitted through the illumination lens 13 for each screen.
2, and a hologram sensitive material 9 is placed on the diffusion screen 7.
The projection lens 14 projects the object so that the same object as the original object appears when viewed from above. A hologram sensitive material 9 is placed away from the diffusion screen 7 by the same distance as the distance i between the object 1 and the camera 10 in the first stage, and a slit 8 with a width d is placed in front of it to interfere with the reference beam 15. hologram(
(called an elemental hologram). At the same time as the positive image 11 is replaced one after another, the slit 8 is also moved by d.
Multiple elemental holograms line up horizontally to create one composite hologram. When the created composite hologram is illuminated with a reproduction point light source placed at the same position as the original reference beam 15, it is diffused as shown in Figure 5. The reconstructed images from each element hologram are superimposed on the surface where the screen 7 was. When this reconstructed image is observed with both eyes from near the back surface of the composite hologram, a three-dimensional image is reconstructed using the same principle as stereoscopic vision in stereo photography.

The method for creating a multiplex hologram is the same as for the holographic stereo duram in FIG. 4, and in FIG. Above, in the vertical direction, a combination lens system of a cylindrical lens and a spherical lens is used to focus the pupil of the lens 14 on the position of the eye considered to observe the reconstructed image, and the hologram sensitive material 9 is moved instead of moving the slit 8. are different.

[Problem that the invention seeks to solve]

In both holographic stereo durams and multiplex holograms, there are processing times such as recording the object, developing the film, and feeding the film during hologram creation.
Accuracy in film positioning is required. Since the element hologram has a slit shape, the image is damaged by the slit during reproduction. To avoid this, it is usually necessary to set the slit width d to 1++n or less. Therefore, a large number of input images are inevitably required,
If a two-step process as shown in FIGS. 4 and 5 is performed, the recording time will be correspondingly longer.

Therefore, the present invention solves the problems of the prior art as described above when creating a holographic stereogram or a multiplex hologram (hereinafter referred to as holographic stereogram etc. unless otherwise specified). Only 1 step process without completing 2 step process,
The purpose is to provide a method by which synthetic holograms can be created.

[Means for solving problems]

To this end, the synthetic hologram recording method for stereoscopic image observation of the present invention is a synthetic hologram recording method for stereoscopic image observation in which a large number of elemental holograms are arranged in parallel. It uses the image of

[Effect]

The synthetic hologram recording method for stereoscopic image observation of the present invention uses an image of an object converted by an incoherent-coherent image conversion element as an input image, thereby producing a hologram (element hologram) of an image having parallax from multiple directions of the object. ) can be created directly by sequentially subtracting them.

〔Example〕

With reference to FIG. 1, a method for directly creating a holographic stereodulum of an object l according to the invention will be explained. The object 1 is illuminated by incoherent light 20 and its image is formed by the taking lens 2 onto the input surface of the incoherent-coherent image converter x-ray 3 . The output surface of the incoherent-coherent image conversion element 3 is illuminated by a laser beam 4 that has passed through a beam expander 5 and a half mirror 6, the input incoherent image is converted into a coherent image, and the coherent image light is reflected by the half mirror 6. , an image is formed on the diffusion screen 7 by the projection lens 14 as in the case of FIG.

Then, element holograms are sequentially recorded on the hologram sensitive material 9 via the moving slit 8 in the same manner as in FIG. Note that the reference beam 15 is not shown in FIG. 1, and in FIG. The points are different. When creating a multiplex hologram according to the present invention, a combination lens system of a cylindrical lens and a spherical lens is used instead of the diffusion screen 7, and a hologram sensitive material is used instead of moving the slit 8, as described in the prior art. All you have to do is move 9.

Here, incoherent-coherent image conversion element 3
There are various known methods such as those that combine a photoconductor and an electro-optic crystal plate, but for example, an M'SLM (microchannel spatial light modulator) as shown in Fig. 2 is used. . The MSLM includes a photocathode 21, a focusing electrode 22, and a microchannel plate (
The structure from the photocathode 21 to the MCP 23 is the same as that of a normal image intensifier. is converted into a photoelectron image, multiplied by the MCP 23, and then forms a charge pattern on the surface of the electro-optic crystal 25.

The electric field across the crystal 25 changes depending on the charge pattern, and the refractive index (birefringence) of the crystal 25 changes due to the electro-optic effect. Here, when the crystal 25 is irradiated with a linearly polarized reading laser beam, the polarization state of the reflected light from the dielectric mirror provided on the charge accumulation surface of the crystal 25 changes according to the accumulated charge, so the analyzer By passing through, a coherent image corresponding to the input incoherent image is obtained. Controlling the charge on the surface of the crystal 25 (m<writing, erasing) is performed efficiently by appropriately setting the secondary electron supplementary current collection bridge voltage and the crystal back voltage, making use of the secondary electron emission characteristics of the crystal surface. be able to. MSLM is capable of simultaneously performing light amplification and image processing.

A two-dimensional logic operation device as shown in FIG. 3 using three such MSLMs is known (Oplus E N
o, 86 (1987, 1) PP, 64-68).

In FIG. 3, 30 represents a He-Ne laser, 31 represents a first input image, 32 represents a second input image, and 33 represents an output surface lean. And the three MSLMs are MS
Indicated by LM1-3. Also, M is the mirror H,
M is half mirror 0, C, H, M is cube half mirror, P, B.

S represents a polarizing beam splitter, and v, p, and s represent voltage-controlled phase shifters.

When such a two-dimensional logical operation device is used, the input image 3
For example, while irradiating the output screen of MSLMl with laser light,
When the reflected light is irradiated onto the output screen of MSLM2, the reflected light becomes the product of input images 31 and 32. By writing this into MSLM3 and reading it out with a laser beam, the product of both input images is obtained. Can be read. Therefore, the object l in FIG.
The input image 32 is processed using another image such as a filter, and the output coherent image of MS LM3 is formed into a hologram bridge in the same manner as in FIG. etc. can also be created.

〔Effect of the invention〕

As described above, according to the present invention, when photographing each element hologram such as a holographic stereo duram, instead of using a conventionally used film image as an input image, the input image is converted by an incoherent-coherent image conversion element. Since the direct image of the object is used, there is no need to perform the conventional two-step imaging process, which reduces (a) recording time, (b) film development time, and (c) In addition to making it possible to guarantee input image position settings,
(d) It is also possible to process input images by utilizing the information processing function of the incoherent image conversion element.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a hologram recording method according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of an MSLM, Fig. 3 is an optical path diagram showing the configuration of a two-dimensional logic operation device, and Fig. 4 is a conventional hologram recording method. FIG. 5 is an explanatory diagram showing a method for recording an input image of a graphic stereo duram. FIG. 5 is a horizontal sectional view (a) and a vertical sectional view (b) of a conventional holographic stereo duram imaging device. l...Object, 2...Photographing lens, 3...Incoherent-coherent image conversion element, 4...Laser light, 5...Beam expander, 6...Half mirror
17... Diffusion screen, 8... Slit, 9...
・Hologram sensitive material, 14... Projection lens, 20...
Incoherent light. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masanobu Hirukawa Figure 1 Figure 2

Claims (4)

[Claims] (1) A hologram recording method for stereoscopic image observation in which a large number of elemental holograms are arranged in parallel, which is characterized in that an image of an object converted by an incoherent-coherent image conversion element is used as an input image. (2) The hologram recording method according to claim 1, wherein the composite hologram to be recorded is a holographic stereogram. (3) The hologram recording method according to claim 1, wherein the composite hologram to be recorded is a multiplex hologram. (4) The hologram recording method according to any one of claims 1 to 3, wherein the input image is image-processed by an incoherent-coherent image conversion element.