JPH02205816A - Method for displaying dynamic three-dimensional image - Google Patents

Abstract

PURPOSE:To form the dynamic three-dimensional image which has complete parallax by passing input luminous flux whose spatial phase distribution is known previously through a spatial phase modulating device. CONSTITUTION:A dynamic three-dimensional image display device is equipped with a laser light source Ls, lenses L1-L6, a mirror M, a beam splitter B, the spatial phase modulating device SPL, an output plane OP, and a controller C, and a light source which emits spatially coherent laser light is used. The spatial phase modulating device SPL is arranged in the optical path of the luminous flux from the laser light source Ls to be modulated for the modulation of the spatial phase distribution of the light and converts the spatial phase distribution of the input luminous flux from an object to be displayed as an image into an electric signal, i.e. a Fresnel-converted spatial phase distribution. Consequently, an observer who observes the output light can see the complete dynamic three-dimensional image of the object with parallax effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for displaying dynamic three-dimensional images with parallax.

[Prior Art] Conventionally used methods for displaying dynamic three-dimensional images utilize the physiological characteristics of the human eye and brain. This conventional method typically projects one or more specially designed two-dimensional images that the brain considers to be three-dimensional images and is viewed by an observer. One specific example of this method is stereoscopic cinema. In stereoscopic movies, each eye receives a slightly different image, creating the impression that you are viewing a three-dimensional image due to the stereophotographic effect.

Normally, two images are projected simultaneously onto the same screen, but the images are adjusted to differ in polarity or color, so that each viewer's eye receives only the correct image. There is.

[Problems to be Solved by the Invention] However, in most of these conventional methods, the way an observer sees a three-dimensional image is based solely on the observer's impression, and depends on the function of the observer's brain and the function of each eye. This is simply an impression created by combining the three-dimensional images seen by the person.

In order to create a pseudo 3D image that has the characteristics of a true 3D image, it is necessary that the pseudo 3D image has parallax. How is the image formed? J! have no m effect at all, or
Alternatively, it is only possible to form parallax from one direction, and it is not possible to form a satisfactory three-dimensional image with parallax when observed from all directions.

Holography is another method of displaying three-dimensional images.
There are some that use

In holography, Fresnel diffraction of reproduction light in a fine grating forms light waves whose phase distribution is the same as the phase distribution of light coming from the object from which the hologram was created.

In this case, the hologram functions as a spatial phase modulator, and the phase modulation applied to the reproduction beam is determined by the relative position of the diffraction lines of the grating or hologram.

However, in order to obtain a realistic reproduced image, the hologram must have many diffraction lines, and therefore the resolution of the hologram in which the diffraction lines are written must be extremely high. However, the amount of data to be written into this hologram is extremely large, and the amount of related data required is unrealistically large.

This invention was made in view of the above circumstances, and it is possible to form a dynamic 3D image with perfect parallax, and to reduce the amount of data required to form a dynamic 3D image. The object of the present invention is to provide a method for displaying dynamic three-dimensional images that can be used to display dynamic three-dimensional images.

[Means for Solving the Problem] Corresponding to this object, the dynamic three-dimensional image display method of the present invention changes the spatial phase distribution of the input light flux from the spatial phase distribution of the light flux from the object to be displayed as an image. The input light flux whose spatial phase distribution is known in advance is passed through a spatial phase modulation device that converts the spatial phase distribution into a Fresnel-transformed spatial phase distribution according to an electric signal, and the output light of the spatial phase modulation device is observed. It is characterized by

[Operation] The input light beam passes through the spatial phase modulator. Therefore, the phase distribution of the input light beam is converted into the phase distribution of the Fresnel diffracted light of the light coming from the object to be imaged.

This converted output light is similar or identical to the light flux coming from the object. Control of the spatial phase modulator by electrical signals, such as video signals, forms a sequence of images so that the viewer of the output light sees a fully dynamic three-dimensional image of the object with parallax effects. Can be done.

[Example] Hereinafter, details of the present invention will be explained with reference to drawings showing an example.

In FIG. 1, reference numeral 1 denotes a dynamic three-dimensional image display device used when implementing the dynamic three-dimensional image display method of the present invention. The dynamic three-dimensional image display device 1 has a laser light source and a lens L1. L2. L3. L4゜S ゝL5. L6, mirror M1, beam splitter B1, spatial phase modulator SPL, output plane OP, such as a screen, and control device C. HeN as a laser light source
A light source that emits a spatially coherent laser, such as an e-laser light source, is used.

The spatial phase modulator SPL is used to modulate the spatial phase distribution of light by being placed in the optical path of the light beam from the laser light source that is the target of modulation.

As shown in FIGS. 2 and 3, this spatial phase modulator SPL has a liquid crystal layer 4 sandwiched between two glass plates 2 and 3.
(approximately 6 μm thick). These glass plates2.
Each of the glass plates 3 is provided with an electrode 5, 6, and the electrode 6 of one glass plate 3 is made up of small electrodes, and the voltage of each small electrode is individually variable. As shown in FIG. 2, a large number of the small electrodes 6 are densely arranged in a matrix, and an electric field can be individually applied by a scanning electrode drive circuit 7 and a signal electrode drive circuit 8. These small electrodes 6 are arranged in a rectangular shape.
The electronic circuits (scanning electrode drive circuit 7, signal electrode drive circuit 8) placed in 60×120 pixels can modulate the electric field distribution across the liquid crystal layer 4 according to the control device C or an external video signal. It's equipped like that. The inner surface of each glass plate 2.3 is treated to have a twisted nematic mode with a twist of 0 to 3603. The alignment of molecules on the surface of the sawed glass plate 2.3 is the fourth
As shown in the figure.

FIG. 4 is an explanatory diagram showing the alignment state of polarized light of incident light due to liquid crystal molecules in the liquid crystal layer 4. FIG.

In the figure, 21 indicates the orientation direction of liquid crystal molecules on the front surface of the liquid crystal JI4.

22 indicates the orientation direction of liquid crystal molecules on the rear surface of the liquid crystal layer 4.

23 indicates the direction of orientation of the electric field vector of light incident from the front surface of the liquid crystal WJ4.

24 indicates the direction of orientation of the electric field vector of light emitted from the rear surface of the liquid crystal layer 4 (the electric field across the liquid crystal layer 4 is set to a threshold value).

The light beam from the laser light source is passed through the lens L1. L2, and then passes through a beam splitter B to reach a spatial phase modulator E (SPL). In this embodiment, the spatial phase modulator SPL consists of a twisted nematic liquid crystal sandwiched between two glass plates, as described above. , on which a transparent conductive pixel electrode is provided.

These electrodes create an electric field across the liquid crystal layer so that the orientation of the liquid crystals in the liquid crystal layer is modified in response to control and video signals from the computer. This creates a tilt distribution with respect to the plane of the liquid crystal layer and causes a spatial change in the refractive index depending on the control signal or video signal. Therefore, the spatial phase distribution of light passing through the liquid crystal layer is modified by this refractive index distribution. The material properties of the spatial phase modulation layer [SPL and the thickness of the liquid crystal layer are selected such that when light passes twice through the spatial phase modulation layer aspt-, a phase change of at least 2π is possible.

The light emitted from the spatial phase modulation layer ff1sPL is collected by the afocal imaging system 9. Afocal image system 9
is lens L3. L4 and a spatial phase modulator S
PL is imaged onto the plane of mirror M1. Mirror M1 reflects the incident light and passes it through afocal imaging system 9 to spatial phase modulator SPL from the opposite side. Lens L3. L
4. The optical system consisting of the mirror M1 forms an image of the spatial phase modulator SPL by the reflected light, and when the image enters the spatial phase modulator SPL again, the pixels of the image form the image of the spatial phase modulator SPL. Adjusted to match the pixel.

The reflected image by the mirror M1 of the spatial phase modulator tsPL and the light immediately after passing once through the spatial phase modulator SPL have the same phase distribution. As described above, the light with this phase distribution passes through the spatial phase modulation layer @SPL again from the opposite side. As a result, the spatial phase modulation of the light is doubled. The spatial phase distribution of the light that has undergone this twice the spatial phase modulation will be exactly the same as that of the object whose image is to be displayed if it is illuminated with coherent light having the same wavelength as the wavelength of the aforementioned light. The spatial phase modulator SPL is adjusted by a control signal from the control device C or an external video signal so that it is the same as the spatial phase distribution of the incoming light.

Therefore, the light that finally exits the spatial phase modulating layer SPL (after passing twice) has the same spatial phase as the light coming from the object,
An observer observing this light will see a three-dimensional image of the object with parallax.

The light that finally exits the intermediate phase change WA device SPL is direction-changed by the beam splitter B, and then passes through the lenses L5. death. Head to.

Lens L5. L6 forms the plane of the spatial phase modulation layer asPL on the output plane OP of the optical system 11. By using this optical system 11, it is possible to completely match the spatial phase distribution on the output plane OP of the optical system 11 with the spatial phase distribution immediately after the light passes through the spatial phase modulation layer @SPL twice. , and it becomes possible to approach the wavefront of the light that has passed through the spatial phase modulator SPL.

In this embodiment, the spatial phase modulator SPL uses nematic liquid crystal. The polarity of the light entering the spatial phase modulator S PL from the laser light source L is adjusted just before the beam splitter B so that it coincides with the direction of the liquid crystal.

This is effective in minimizing the birefringence effect in the liquid crystal layer and in making the polarization state of the light that passes through the spatial phase modulator SPL twice and exits the same as the input light of the laser. Therefore, in this case the polarization of the output light caused by the change in the tilt of the molecules of the liquid crystal layer is minimized.

[Effects of the Invention] According to the present invention, it is possible to form light waves that are extremely similar to the light waves coming from the object itself, rather than using the characteristics of the physiological combination between the human eye and the brain.
Therefore, dynamic three-dimensional images can be displayed.

In this invention, the spatial phase distribution of the reconstructed beam is modified by a spatial phase modulator rather than using diffraction by a hologram, so the number of pixels required for the spatial phase modulator is reduced by the number of pixels of the image to be reconstructed. smaller than the number of . Therefore, the amount of data required to form a dynamic three-dimensional image can also be significantly reduced.

LCD-like materials and eyelids used in LCD TVs?
- The deformable gel used in Eidophor can be used as a spatial phase modulator, and such a spatial phase modulator can modify the spatial phase distribution of the light flux passing through it according to the video signal. .

In the dynamic three-dimensional image display device of the present invention, a spatially coherent light beam whose phase distribution is known in advance is passed through a spatial phase modulation device, where the phase distribution of this light beam is converted into a Fresnel diffracted light beam coming from an object. Convert to phase distribution. Therefore, the output light from the spatial phase modulator SPL is very similar or identical to the light beam coming from the object, allowing the viewer to observe a complete three-dimensional image of the object with parallax effects.

In particular, if the spatial phase distribution is modulated by the spatial phase modulator SPL at a video rate, a sequence of three-dimensional images can be formed, and the viewer can observe a dynamic three-dimensional image.

Furthermore, if a spatial phase modulation device is used in conjunction with a color filter with pixels, and if these colors are simultaneously irradiated with coherent light beams of different colors that match the filter, it is possible to display a dynamic three-dimensional color image. It is.

7... Scanning electrode drive circuit, 8... Signal electrode drive circuit, 9... Afocal image system, 11... Optical system, L
...Laser light source, Ll, L2. L3. L4. L5. L6...Lens, B
...beam splitter, SPL...spatial phase modulator, OP...output plane, C...control device, 21.22
．． 23.25...Orientation direction

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a dynamic three-dimensional image display device, Fig. 2 is a schematic cross-sectional explanatory diagram of a spatial phase modulation device, Fig. 3 is a schematic plan explanatory diagram of the spatial phase modulation device, and Fig. 4 is a spatial FIG. 3 is an explanatory diagram showing the polarization of incident light incident on a phase modulation device and the orientation of liquid crystal molecules. 1... Dynamic three-dimensional image display device, 2.3... Glass plate, 4... Liquid crystal device, 5...
Electrode, 6...Small electrode, cause

Claims (3)

[Claims] (1) The spatial phase distribution is known in advance to a spatial phase modulation device that converts the spatial phase distribution of the input light flux into a spatial phase distribution obtained by Fresnel transformation of the spatial phase distribution of the light flux from the object to be displayed as an image into an electric signal. A method for displaying a dynamic three-dimensional image, characterized in that the method is configured to allow the input light beam to pass through and observe the output light of the spatial phase modulator. (2) The method for displaying a dynamic three-dimensional image according to claim 1, wherein the electric signal is a video signal. (3) A method for displaying a dynamic three-dimensional image according to claim 1 or 2, characterized in that a color filter is used together with the spatial phase modulation device, and the input light beam is composed of a plurality of light beams having different wavelengths.