JP2000112323A - Holographic stereogram forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clear holographic stereogram high in contrast and gradation by eliminating a double image on liquid crystal display elements caused by vibration or the like. SOLUTION: This device is provided with a photosensitive material 105 which is a recording object and is nippedly held by linear slits 104, a curved space light modulator 102 which is arranged to oppose the slits 104 and has a prescribed curvature and a mirror 103 which is opposedly arranged in the vicinity of the slits 104 on the inner side of the modulator 102 and guides incident object light beams to the inner side of the modulator 102. The modulator 102 diffuses light beams to at least one direction and is provided with a diffusing plate which is constituted of a liquid crystal layer and a reflection plate with a gap of less than 500 microns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic stereogram forming apparatus for sequentially displaying parallax images using a reflection type display device and forming a stereoscopic image by sequentially recording the images in a point or linear manner. .

[0002]

2. Description of the Related Art Conventionally, holographic stereograms have been used.
m; HS) has attracted attention as a three-dimensional image technique capable of easily creating a good three-dimensional image, and many engineers are conducting research for improving the quality.

As reference technical documents related to the holographic stereogram, for example, Japanese Patent Laid-Open No.
No. 184, "Method of creating holographic stereogram" is disclosed. Here, in particular, a method of projecting a parallax image on a reflection / diffusion plate, which avoids a decrease in image quality of a projection original image, has excellent stability against vibration during photographing / recording, and has a simple and compact optical system. It proposes realizing the configuration.

However, even in the optical system configured as described above, the space required for the recording light to pass therethrough becomes large.
Therefore, the present inventors have already proposed to use a reflection-type spatial light modulator instead of the diffuser plate to realize a device that is much more compact than in the past. In addition, by bending the spatial light modulator to a predetermined curvature, a wider viewing zone than ever before can be obtained.

[0005]

However, in the prior art as described above, if the arrangement for recording the reflected light from the spatial light modulator is simply adopted, the spatial light modulation Since the light reflected from the surface of the machine overlaps with the object light to be recorded and is irradiated as background light, the contrast is lowered.

Further, glass is mainly used as a substrate material of a liquid crystal display element, and a method of attaching a reflector to the back side sandwiching a liquid crystal layer is generally used. In this case, the gap between the liquid crystal layer and the reflector is generally used. Is considerably long, so that the reflected light is superimposed on an adjacent pixel to easily form a double image. For this reason,
When such double images are recorded, holographic
Reproduced images of stereograms are out of focus or have poor gradation.

Furthermore, it is necessary to form a sufficiently accurate concave mirror on the liquid crystal display element in order to arrange the reflected light so as to be accurately incident on the slit or the pinhole on the photosensitive material. In addition, when used in portable electronic devices and the like, it is necessary to frequently adjust the deformation caused by the transportation of the device or vibration from the floor.

The present invention has been made in view of the above, and eliminates a double image of a liquid crystal display element due to vibration or the like to obtain a clear holographic stereogram having high contrast and gradation. The purpose is to:

[0009]

According to a first aspect of the present invention, there is provided a holographic stereogram forming apparatus, comprising: a photosensitive material to be recorded sandwiched between linear slits; A curved spatial light modulator arranged opposite to the slit and having a predetermined curvature;
A mirror disposed in the vicinity of the slit and inside the spatial light modulator to guide incident object light to the inside of the spatial light modulator; A light diffusing plate is provided which diffuses light in the direction and has a gap between the liquid crystal layer and the reflecting plate of 500 microns or less.

Further, in the holographic stereogram forming apparatus according to the second aspect, the diffusion amount of the diffusion plate is set to 5 degrees or less.

In a holographic stereogram forming apparatus according to a third aspect of the present invention, the ratio of the repeating unit of the diffusion element of the diffusion plate to the repeating unit of the liquid crystal display element of the spatial light modulator is 1: 1. The following is assumed.

Further, in the holographic stereogram forming apparatus according to claim 4, the diffusion plate is a reflection type hologram.

Further, in the holographic stereogram forming apparatus according to the fifth aspect, the driving electrode for driving the liquid crystal of the spatial light modulator has a light reflecting function.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the holographic stereogram forming apparatus of the present invention will be described below in detail with reference to the accompanying drawings.

(Configuration and Operation of Reflective Display) FIG.
FIG. 1 is an explanatory diagram illustrating a configuration of a holographic stereogram forming device according to an embodiment of the present invention. In the figure,
The photosensitive material 105 to be recorded is a linear slit 104.
It is held in a state sandwiched by. The spatial light modulator 102 (see FIG. 2 or FIG. 3 for the detailed configuration) is arranged at a position facing one of the slits 104. Further, in the vicinity of the slit 104, the spatial light modulator 10
A hemispherical mirror having a predetermined curvature is disposed at a position facing the mirror 2.

The parallax image is generally exposed on the photosensitive material 105 in a linear or dot shape, and intersects on the photosensitive material 105 with reference light incident on the photosensitive material 105 in the same or opposite direction as the incident light. That is, in the configuration of FIG.
The incident light (object light) 101 is, as shown in FIG.
The light is diffused / reflected, enters the spatial light modulator 102 as diffuse reflected light 107, is modulated, and is condensed on the slit 104. At the same time, the reference light 106 branched from the incident light (object light) 101 from a light source (not shown) by a branching means (not shown) enters from the back of the photosensitive material 105.

In this embodiment, the spatial light modulator 102
The light reflected toward the slit 104 is diffused at least in the width direction of the slit 104. For this reason, almost the same incident light is reproduced in a wide range near the slit 104, so that even if the arrangement of the slit 104 and the spatial light modulator 102 is slightly changed, stable image formation can be achieved. It can be carried out. Further, since the optical functional components are arranged as described above, there is also an effect that it is not necessary to provide a precise adjusting means (mechanism).

(Structural Example 1 of Spatial Light Modulator) FIG.
FIG. 2 is an explanatory diagram showing an enlarged cross section of a first configuration example of the spatial light modulator 102 of the holographic stereogram forming apparatus in FIG. In the figure, the spatial light modulator 102 is formed with a liquid crystal layer 204 sandwiched between substrates 205 having transparent drive electrodes 203. The incident light passes through the liquid crystal layer 204, is reflected by the reflector 201, passes through the liquid crystal layer 204 again, is modulated, and is emitted.

In this embodiment, a diffusion plate (in this example, the diffusion plate 200 is provided between the substrate 202 and the reflection plate 201) is arranged on the surface of the substrate 205 or between the substrate 202 and the reflection plate 201. I have. The substrate 205 has a thickness of 500 microns or less, preferably 200 microns or less.

Further, since the width of the driving electrode 203 is about 200 to 40 microns, when the thickness of the substrate 205 exceeds the above-mentioned thickness, when the incident light passes through the liquid crystal layer 204 twice, the adjacent electrode The image tends to be superimposed on the image, and a defective image such as a decrease in the shape and contrast of the image easily occurs. Thus, the substrate 205 may be made of, for example, very thin glass or a resin film such as a polycarbonate resin. In this case, it is preferable to use a resin film having excellent workability and moldability.

When the diffusion amount of the diffusion plate is at an angle of 5 degrees or less with respect to the reflected light having no diffusion, the occurrence of the defective image can be easily suppressed, and the amount of incident light is unnecessarily increased. It can be used effectively without any.

As the diffusion plate, known means such as a cylindrical lens array, a prism array, or a holographic optical element can be used, for example, also serving as a reflection plate. In this case, the ratio of the repeating unit of the optical array to the repeating unit of the liquid crystal display element is preferably 1/1 or less. Preferably, the width of the array should be 以下 or less of the width of the driving electrodes of the liquid crystal. In addition,
If it is larger than this, bias due to the reflection direction of the modulated light is likely to occur, and a brightness distribution depending on the reproduction direction will occur.

In particular, when the diffusion plate is a reflection type hologram optical element, the liquid crystal element can be easily formed, so that the productivity is improved and the direction of the diffused light can be controlled more easily. Further, by making the position of the hologram of the holographic optical element coincide with the position of the drive electrode of the liquid crystal, light irrelevant to display can be transmitted, and the black matrix between the electrodes is not required.

(Structural Example 2 of Spatial Light Modulator) FIG.
FIG. 5 is an explanatory diagram showing an enlarged cross section of a second configuration example of the spatial light modulator 102 of the holographic stereogram forming apparatus in FIG. In the figure, the spatial light modulator 102 has a configuration in which reflection of incident light is shared by the drive electrode 302 of the liquid crystal layer 303, in contrast to the configuration of FIG. Such a configuration is realized by forming a reflective and conductive material such as aluminum on the substrate 301 by vapor deposition or the like.

In this case, since the incident light is reflected without exiting from the liquid crystal layer 303, the above-mentioned overlapping of the images does not occur. Further, noise due to light passing between the electrodes can be reduced as in the case of the holographic optical element described above. Further, the diffusion plate can be arranged on the surface of the substrate 304, for example.

(Example of Creating Holographic Stereogram) Next, a specific example of creating a holographic stereogram by the holographic stereogram forming apparatus described above will be described.

Creation Example (1) Here, a holographic stereogram is created with the configuration of the holographic stereogram forming apparatus shown in FIG. As the photosensitive material 105, OMNIDEX (trade name) manufactured by DuPont (US) is used. The film-shaped photosensitive material is held between both sides by slits having a distance of 0.2 m, and one side of the film is held, and the film position can be moved by a uniaxial stage. A louver film for preventing reflection and a lenticular lens for diffusing light in the length direction of the slit are disposed on the surface of the slit on the object light side.

A spatial light modulator (liquid crystal display element) 10
2 is created with the configuration shown in FIG. The width of the driving electrode 302 is 250 microns, the thickness of the substrate 301 is 150 microns, and a polycarbonate film is used as a material of the substrate 301. A 50 micron pitch lenticular lens is used for the reflector, and a polarizing plate is attached to the surface of the liquid crystal display device.

It has been confirmed that the diffusivity of the light reflected from the liquid crystal display panel has a width of 6 degrees in the horizontal direction. This liquid crystal display panel is curved and arranged on the front surface of the slit 104, controlled by a personal computer, displays a parallax image, and simultaneously performs exposure by opening a shutter.
Each time the exposure is performed for a predetermined time, the shutter is closed to block the incident light of both the object light and the reference light, and the photosensitive material is moved by the slit width, and at the same time, the image on the liquid crystal display element is rewritten and the exposure operation is performed again. Repeat.

As a result, it was proved that the obtained image reproduced a good halftone and was a clear image without background noise. In addition, the image obtained by intentionally finely adjusting the position of the liquid crystal display element and slightly deviating the slit position from the accurate focusing position to create a holographic stereogram is the same as in the first case. Good,
It turned out to be something without any color.

Now, for comparison with the above-described embodiment, a liquid crystal display element is formed using a thin glass substrate as a substrate, and other constitutional conditions are the same as in the above-described embodiment, and a holographic stereogram is formed. Was done. The thickness of the glass substrate is 1.0 mm. The resulting hologram image had blurred outlines and poor reproduction of halftones.

Preparation Example (2) Here, a holographic stereogram is prepared in the same manner as in the above embodiment except that a 300 μm pitch lenticular lens of a reflector is used. As a result, a good stereoscopic image could be observed in the obtained hologram image, although the noise partially overlapped.

Example of preparation (3) Here, OMNID manufactured by DuPont, USA
Using EX (trade name), a reflection hologram of Lippmann type is created such that the diffusion angle becomes 4 degrees. Using this reflection type hologram as a reflection plate, a holographic stereogram is created in the same manner as in the above embodiment. As a result, in the obtained hologram image, a good half tone was reproduced, and a clear image without background noise could be confirmed.

Production Example (4) Here, a liquid crystal display element is produced with the configuration as shown in FIG. At this time, aluminium is used for the drive electrode, and the surface thereof is subjected to a surface roughening treatment so as to be diffusely reflected. Using this liquid crystal display element, a holographic stereogram is created in the same manner as in the above embodiment. As a result,
The resulting hologram image reproduces good halftones,
A clear image without background noise could be confirmed.

[0035]

As described above, according to the holographic stereogram forming apparatus according to the present invention (claim 1), the object light is diffused and reflected by the mirror, and enters the spatial light modulator as diffuse reflected light. Then, the light is modulated and condensed on the slit, and at the same time, the reference light branched from the object light enters from the back surface of the photosensitive material. At this time, the light reflected from the spatial light modulator toward the slit is diffused at least in the width direction, and almost the same incident light is reproduced in a wide range near the slit. Even if the arrangement of the machines slightly fluctuates, stable image formation can be performed, and since such optical functional parts are arranged, there is no need to provide precise adjustment means (mechanism). Also play.

In particular, by providing a diffusion plate which diffuses light in at least one direction and the distance between the liquid crystal layer and the reflection plate is set to 500 μm or less, the liquid crystal display element may be doubled due to fluctuations in the device. The occurrence of a defective image due to an image can be eliminated, and a clear image having high contrast and gradation can be reproduced.

Further, according to the holographic stereogram forming apparatus according to the present invention (claim 2), since the diffusion amount of the diffusion plate is set to 5 degrees or less, it is possible to avoid the diffraction effect of the liquid crystal and the like, and Can be used effectively.

According to the holographic stereogram forming apparatus of the present invention, the ratio between the repeating unit of the diffusion element of the diffusion plate and the repeating unit of the liquid crystal display element is set to 1: 1 or less. In addition, the diffraction effect of the liquid crystal can be avoided, and the light can be effectively used.

According to the holographic stereogram forming apparatus according to the present invention (claim 4), the configuration of the apparatus is simplified by using a reflection type hologram as the diffusion plate, and noise due to unnecessary light is reduced. Can be reduced, and an image with good gradation can be reproduced.

According to the holographic stereogram forming apparatus according to the present invention (claim 5), since the driving electrodes for driving the liquid crystal of the spatial light modulator have the function of reflecting light, the configuration of the apparatus is simplified. In addition, noise due to unnecessary light can be reduced, and an image with good gradation can be reproduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a holographic stereogram forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an enlarged cross section of a first configuration example of a spatial light modulator of the holographic stereogram forming device in FIG.

FIG. 3 is an explanatory diagram showing an enlarged cross section of a second configuration example of the spatial light modulator of the holographic stereogram forming device in FIG. 1;

[Explanation of symbols]

 Reference Signs List 101 incident light (object light) 102 spatial light modulator 103 mirror 104 slit 105 photosensitive material 106 incident light (reference light) 107 diffused light 200 diffuser 201 reflective plate 202, 205, 301, 304 substrate 203, 302 drive electrode 204, 303 liquid crystal layer

Claims (5)

[Claims] A photosensitive material to be recorded sandwiched between linear slits;
A curved spatial light modulator having a predetermined curvature, and a mirror disposed in the vicinity of the slit and inside the spatial light modulator so as to guide incident object light to the inside of the spatial light modulator. Holographic stereogram, characterized in that the spatial light modulator comprises a diffuser plate for diffusing light in at least one direction and having a distance between the liquid crystal layer and the reflector plate of 500 microns or less. Forming equipment. 2. The holographic stereogram forming apparatus according to claim 1, wherein the diffusion amount of the diffusion plate is set to 5 degrees or less. 3. The ratio of a repeating unit of a diffusion element of the diffusion plate to a repeating unit of a liquid crystal display element of the spatial light modulator is 1: 1 or less.
The holographic stereogram forming device according to 1. 4. The holographic stereogram forming apparatus according to claim 1, wherein the diffusion plate is a reflection type hologram. 5. The holographic stereogram forming apparatus according to claim 1, wherein a driving electrode for driving a liquid crystal of the spatial light modulator has a function of reflecting light.