JP2000259069A - Three-dimensional hologram display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a display picture have high definition, to obtain a high- quality display picture and to extend the visual field by storing object light generated by a spatial optical modulator in a photorefractive recording medium and collectively displaying plural pictures of the object light. SOLUTION: At the time of recording a three-dimensional picture, incident light 3' for hologram object light is made incident, a movable mirror is scanned while displaying one of plural holograms on the spatial optical modulator 5, and plural three-dimensional pictures in a state where the incident angles of the light 3' are mutually different are multiply recorded on the photorefractive recording medium 12. Besides, by switching a pattern for generating a hologram displayed on the modulator 5 and repeating the same operation, plural three- dimensional pictures with different incidet angles are multiply recorded on the medium 12. At the time of reproducing the three-dimensional picture, the light 3' is intercepted by a shutter 17 and only reference light 15 is radiated to the medium 12, whereby the multiply recorded three-dimensional pictures are collectively reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional hologram display device using a spatial light modulator as a hologram object light source.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional three-dimensional hologram display device using a spatial light modulator as a hologram object light source. The spatial light modulator control device 4 generates the spatial light modulator 5 so that the diffracted light by irradiating the light from the laser 1 to the spatial light modulator 5 becomes the hologram object light 7 to be displayed. The pattern to be calculated is calculated, and the light from the laser 1 is diffracted by the spatial light modulator 5 in which the calculation result pattern is generated, so that the desired hologram object light 7 is generated, and the human observes the object light. To perceive a three-dimensional image.

[0003]

However, in the above-mentioned conventional three-dimensional hologram display device, the spatial light modulator has a resolution of at most 10 micrometers (μm).
m), the diffraction angle can be only about 1 degree (reference: 0 plus E, December 1997, 9
1 page). There is a problem that the viewing area is narrow due to the small diffraction angle. In addition, there is a problem that the 0th-order light (6 in FIG. 4) transmitted through the spatial light modulator is included in the display image.

[0004] Further, the pattern that can be displayed on the spatial light modulator due to the low gradation of about several hundreds of the spatial light modulator can only reproduce the object light generated from the minute area of the object.
There is a problem that a three-dimensional image cannot be displayed.

[0005] There is also a method in which a plurality of object lights generated by a spatial light modulator are successively generated in a time-division manner and the image is refined by utilizing the visual lag effect of human eyes (Japanese Patent Application No. 10-363698).
), Several tens of milliseconds per frame (m /
In the switching time of the spatial light modulator of (sec), there is a problem that the reproduced three-dimensional image is a simple three-dimensional image of a rectangular parallelepiped frame as the limit of the definition and the observer perceives the image as flickering. .

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a three-dimensional hologram display device using a spatial light modulator as a hologram object light source. Another object of the present invention is to provide a technology capable of realizing a fine three-dimensional image.

It is another object of the present invention to provide a technique capable of improving the quality of a three-dimensional image in a three-dimensional hologram display device using a spatial light modulator as a hologram object light source.

It is another object of the present invention to provide a technique capable of expanding a spatial viewing area in a three-dimensional hologram display device using a spatial light modulator as a hologram object light source.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0010]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows. (1) In a three-dimensional hologram display device using a spatial light modulator as a hologram object light source, means for sequentially accumulating a plurality of object lights produced by the spatial light modulator on a recording medium having a photorefractive effect; An apparatus comprising means for collectively reproducing the plurality of stored object beams.

According to the means (1), one three-dimensional image generated by the spatial light modulator is a simple image. By displaying a plurality of such images collectively, the display image can be refined. The flickering of the image, which has been a problem in the related art, can be solved by the time-sharing display method.

(2) In a three-dimensional hologram display device using a spatial light modulator as a hologram object light source, means for condensing the zero-order light transmitted through the spatial light modulator with a lens, One or more micromirrors installed on the incident side of a recording medium having a photorefractive effect for the 0th order light, means for reflecting the micromirrors, and a plurality of object lights produced by the spatial modulator The apparatus is provided with means for sequentially accumulating on a recording medium having an effect, and means for collectively reproducing the accumulated plural object lights.

According to the means (2), since the zero-order light transmitted through the spatial light modulator does not affect the display image, a clear display image can be obtained.

(3) The three-dimensional hologram display device according to the above (1) or (2), further comprising means for changing an incident angle of incident light applied to the spatial light modulator.

According to the means (3), as long as the observer located off the optical axis is also located within the swing angle,
It becomes possible to perceive a three-dimensional image. That is, it is possible to realize the expansion of the viewing zone.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments (examples) of the present invention will be described in detail with reference to the drawings. In all the drawings for describing the embodiments (examples), those having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIG. 1 is a schematic configuration diagram showing a schematic configuration of a hologram display device (hologram display device) according to Embodiment 1 of the present invention. In FIG. 1, 1 is a laser, 2 is a beam expander, 3 is parallel incident light, 3 'is incident light for hologram object light, 3''is human light for reference light, 4 is a spatial light modulator controller, and 5 is A spatial light modulator, 6 is a zero-order light, 7 is a hologram object light, 8 is a spatial observation position, 9 is a polarizing beam splitter, 10 is a movable mirror, 11 and 13 are lenses, and 12 is a material having a photorefractive effect. A recording medium (referred to as a photorefractive recording medium), 14 is a fixed mirror, 15 is reference light, 16 is a micro mirror, 17 is a shutter,
8 is an optical axis and 19 is a relay lens.

The hologram display device (hologram display device) of the first embodiment has a configuration as shown in FIG. In the hologram display device (hologram display device) of the first embodiment, the parallel incident light emitted by the laser 1 and expanded by the beam expander 2 is recorded on a photorefractive recording medium 12 by using a polarization beam splitter 9. Are split into incident light 3 'for hologram object light used for reproduction and human light 3''for reference light.

The hologram object light 7 is realized by making the hologram object light incident light 3 ′ incident on the spatial light modulator 5 which has generated the hologram object light generation pattern by the spatial light modulator control device 4. I have. When the hologram object light incident light 3 ′ passes through the spatial light modulator 5, the hologram object light 7 diffracted by the spatial light modulator 5 and 0
It becomes the next light 6. The lens 11 is adjusted so that the zero-order light 6 is condensed on the surface of the photorefractive recording medium 12, and the micromirror 16 reflects the zero-order light 6 condensed on the surface of the photorefractive recording medium 12. It is arranged in the position to be.

The angle of incidence of the hologram object light incident light 3 ′ on the spatial light modulator 5 can be changed by the movable mirror 10. The micromirror 16 is provided only in an area where the condensed zero-order light 6 scanned by the operation of the movable mirror 10 can be reflected. on the other hand,
The human light 3 ″ for reference light is applied to the photorefractive recording medium 12 as reference light 15 via a fixed mirror 14.

In the above configuration, when recording a three-dimensional image, the movable mirror 14 is first scanned and fixed at a certain angle. Next, one of the plurality of hologram object light generation patterns is generated in the spatial light modulator 5, and the hologram object light incident light 3 'and the reference light human light 3''are incident. By these series of operations, the photorefractive recording medium 1
One 3D image in 2 is recorded. The movable mirror 14 is scanned and fixed at another angle, the hologram object light generation pattern displayed on the spatial light modulator 5 is switched, and the hologram object light incident light 3 'and the reference light human radiation 3''are incident. Thereby, the second three-dimensional image is recorded in the photorefractive recording medium 12. By repeating the same operation within the range of the operable swing angle of the movable mirror 14,
A plurality of three-dimensional images are multiplex-recorded on a photorefractive recording medium. At the time of reproducing the three-dimensional image, the shutter 17 blocks the hologram object light incident light 3 ′ and irradiates only the reference light 15 to the photorefractive recording medium 12, thereby collectively reproducing the multiplex-recorded three-dimensional image.

In the configuration of the first embodiment, a plurality of hologram object lights generated via the spatial light modulator 5 can be displayed collectively by using the photorefractive recording medium 12 for three-dimensional image recording. By the collective display of the plurality of hologram object lights, a fine display image exceeding the limit of the spatial light modulator 5 can be obtained.

In addition, since the displayed three-dimensional image is not displayed in a time-division manner, there is no flickering of the image which is a problem in the above-described time-division display. As the laser 1, the spatial light modulator 5, and the photorefractive recording medium 12, a green laser having a wavelength of 532 nm and an output of 150 mW, a transmission spatial light modulator having a resolution of 512 dots × 512 dots, and 0.02 wt% doped CeO ₂ Sr _0.69 Ba _0.31
When a single crystal of Nb ₂ O ₆ was used and the movable mirror 10 was scanned at a swing angle of ± 1 degree, 100 holograms were photorefractively recorded with an exposure time of 5 msec for every 0.02 degree of the swing angle of the movable mirror 10. Recording was possible on the medium 12, and 100 recorded holograms could be reproduced at a time.

The zero-order light 6 transmitted through the spatial light modulator 5
Was condensed by the lens and reflected by the micro mirror 16 provided on the surface of the photorefractive recording medium 12, and could not be observed. Therefore, the image perceived at the observation position 8 of the observer is only the purely multiplexed object light 7, and a more natural and clear three-dimensional display image can be obtained. Since the zero-order light 6 arriving at the surface of the photorefractive recording medium 12 is moved by the scanning of the movable mirror 10, the micro mirror 16 is moved by the continuous or step-scanning method of the movable mirror 10 to form the linear mirror shown in FIG. Alternatively, it has a dot-row arrangement as shown in FIG.

Further, by scanning the movable mirror 10, the object light recorded on the photorefractive recording medium 12 has a spread corresponding to the operation angle of the movable mirror 10, and the observation position 8 When the angle deviated from the optical axis 18, the three-dimensional image could be perceived if the angle of the observation position 8 with respect to the optical axis was within the operation angle.

(Embodiment 2) FIG. 3 is a schematic configuration diagram showing a schematic configuration of a hologram display device according to Embodiment 2 of the present invention. In the hologram display device according to the second embodiment, as shown in FIG.
The parallel incident light 3 radiated by the beam expander 2 and spread by the beam expander 2 is used by a polarizing beam splitter 9 to record and reproduce on a photorefractive recording medium 12 for hologram object light 3 ′ and reference light 3 ′ for reference light. 'Is split. The hologram object light 7 is realized by making the hologram object light human-light 3 'incident on the spatial light modulator 5 in which the hologram object light generation pattern is generated by the spatial light modulator control device 4.

In the second embodiment, the reflection type spatial light modulator 5 is used. The human light 3 ′ for hologram object light is reflected and diffracted by the spatial light modulator to become a zero-order light 6 and a hologram object light 7. The lens 11 is adjusted so that the zero-order light 6 is condensed on the surface of the photorefractive recording medium 12, and the micromirror 16 reflects the zero-order light 6 condensed on the surface of the photorefractive recording medium 12. It is arranged in the position to be.

Further, the angle of incidence of the hologram object light human irradiation light 3 ′ on the spatial light modulator 5 can be changed by the movable mirror 10. The micromirror 16 is provided only in an area where the condensed zero-order light 6 scanned by the operation of the movable mirror 10 is reflected. On the other hand, the reference beam 1 '' is transmitted through the fixed mirror 14 to the reference beam 1 ''.
Irradiate the photorefractive recording medium 12 as 5.

In the above-described configuration, at the time of recording a three-dimensional image, the hologram object light artificial light 3 ′ is made incident, and the movable mirror is scanned while displaying one of a plurality of holograms on the spatial light modulator 5, thereby obtaining a photo. A plurality of three-dimensional images having different incident angles of the hologram object light human light 3 ′ are multiplex-recorded on the reflective recording medium 12.

In addition, a hologram generation pattern displayed on the spatial light modulator 5 is switched, and the same operation is repeated, so that different three-dimensional images of a plurality of images are multiplex-recorded on the photorefractive recording medium 12. At the time of reproducing the three-dimensional image, the shutter 17 blocks the hologram object light 3 ′ for the object light, and irradiates only the reference light 15 to the photorefractive recording medium 12, thereby reproducing the multiplex-recorded three-dimensional image at a time.

The zero-order light 6 transmitted through the spatial light modulator 5
Is reflected by the micromirror 16 provided on the surface of the photorefractive recording medium 12 as in the first embodiment, and cannot be observed, so that a more natural and clear three-dimensional display image can be obtained.

Further, by scanning the movable mirror 10, the object light recorded on the photorefractive recording medium 12 has a spread corresponding to the operation angle of the movable mirror 10, and the observation position 8 of the observer. Was able to perceive a three-dimensional image if the angle of the observation position 8 with respect to the optical axis 18 was within the above-mentioned operation angle, even if the angle deviated from the optical axis 18.

As described above, the invention made by the present inventor is:
Although a specific description has been given based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention.

[0034]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) By accumulating the object light generated by the spatial light modulator on a photorefractive recording medium and displaying a plurality of the images collectively, the displayed image can be refined. (2) Flickering of the displayed image can be solved by the time-division display method. (3) One or more micromirrors are arranged on the surface of the photorefractive recording medium, and the 0th-order light transmitted through the spatial light modulator is blocked by the micromirrors. Since light does not affect the display image, a clear, high-quality display image can be obtained. (4) The viewing range can be expanded by changing the angle of incidence of the incident light that irradiates the spatial light modulator.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a schematic configuration of a hologram display device (hologram display device) according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a state in which a micromirror is arranged on a surface of the photorefractive recording medium according to the first embodiment.

FIG. 3 is a schematic configuration diagram illustrating a schematic configuration of a hologram display device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a schematic configuration of a conventional three-dimensional hologram display device using a spatial light modulator as a hologram object light source.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser, 2 ... Beam expander, 3 ... Parallel incident light, 3 '... Hologram object light incident light, 3 "... Reference light human radiation, 4 ... Spatial light modulator controller, 5 ... Spatial light modulator , 6 ... 0-order light, 7: hologram object light, 8: spatial observation position, 9: polarization beam splitter, 10: movable mirror, 11, 13: lens, 12: photorefractive recording medium, 14: fixed mirror, 15 ... Reference light, 16: micro mirror, 17: shutter, 18: optical axis, 19:
Relay lens.

Continuing on the front page (72) Inventor Ikuo Yagi 3-192, Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. Nippon Telegraph and Telephone Co., Ltd. Nippon Telegraph and Telephone Co., Ltd. No. Nippon Telegraph and Telephone Corporation F term (reference) 2K008 AA00 AA08 BB06 CC03 DD23 EE01 FF07 HH01 HH13 HH18 HH26 5G435 AA00 BB17 CC11 DD02 DD05 DD18 FF05 FF13 FF15 GG01 GG02 GG08 GG10

Claims (3)

[Claims] 1. A three-dimensional hologram display device using a spatial light modulator as a hologram object light source, means for sequentially accumulating a plurality of object lights produced by the spatial light modulator on a recording medium having a photorefractive effect. And a means for collectively reproducing the stored plurality of object lights. 2. A three-dimensional hologram display device using a spatial light modulator as a hologram object light source, means for converging a zero-order light transmitted through the spatial light modulator with a lens.
One or more micromirrors provided on the incident side of the recording medium having a photorefractive effect for the condensed zero-order light, and means for reflecting the micromirrors;
Means for sequentially accumulating a plurality of object lights produced by the spatial modulator on a recording medium having a photorefractive effect,
A three-dimensional hologram display device, comprising: means for collectively reproducing the stored plurality of object lights. 3. The three-dimensional hologram display device according to claim 1, further comprising means for changing an incident angle of incident light applied to said spatial light modulator. .