JP2007041504A - Three-dimensional image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional image display apparatus capable of producing and emitting a light beam group necessary for displaying a stereoscopic image with spatially high density without making the entire apparatus large. <P>SOLUTION: The three-dimensional image display apparatus is equipped with: a light source 10; a light modulation means 30 which modulates a light from the light source by means of respective pixels to produce two-dimensional images and emits a spatial frequency of the produced two-dimensional images along diffraction angles corresponding to a plurality of diffraction orders produced from each pixel; a Fourier transform image formation means 40 which Fourier transforms the spatial frequency of the two-dimensional images emitted from the light modulation means 30 to produce Fourier transform images whose number corresponds to the number of the plurality of diffraction orders; a Fourier transform image selection means 50 which selects the Fourier transform image which corresponds to a desired diffraction order out of the Fourier transform images produced by the number corresponding to the number of the plurality of diffraction orders; and a conjugate image formation means 60 which forms a conjugate image of the Fourier transform image selected by the Fourier transform image selection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a three-dimensional image display device capable of displaying a stereoscopic image.

  Both eyes of the observer can obtain a plurality of stereoscopic images from different viewpoints by preparing a plurality of sets of parallax images or a binocular stereoscopic image technique for obtaining stereoscopic images by observing different images called parallax images. Ocular stereoscopic image technology is known, and many technologies related to these have been developed. However, in the binocular stereoscopic image technology and the multi-view stereoscopic image technology, the stereoscopic image is not located in a space intended as a stereoscopic image, but exists on a two-dimensional display surface, for example. Located at a certain position. Accordingly, convergence and adjustment, which are visual system physiological reactions in particular, do not work together, and eye strain associated therewith is a problem.

  On the other hand, in the real world, information on the surface of an object propagates to an observer's eyeball using light waves as a medium. A holography technique is known as a technique for artificially reproducing a light wave from an object surface that physically exists in the real world. A stereoscopic image using the holography technique uses an interference fringe generated based on light interference, and uses a diffraction wavefront itself generated when the interference fringe is illuminated with light as an image information medium. Therefore, visual system physiological reactions such as convergence and adjustment similar to those when the observer observes an object in the real world occur, and an image with less eye strain can be obtained. Furthermore, the fact that the light wavefront from the object is reproduced means that continuity is ensured in the direction in which image information is transmitted. Therefore, even if the observer's viewpoint moves, it is possible to continuously present appropriate images from different angles according to the movement, and motion parallax can be continuously provided.

  However, in the holography technology, three-dimensional space information of an object is recorded as interference fringes in a two-dimensional space, and the amount of information is extremely large compared to the amount of information in a two-dimensional space such as a photograph of the same object taken. Amount. This is because it can be considered that when the three-dimensional space information is converted into the two-dimensional space information, the information is converted into the density in the two-dimensional space. Therefore, the spatial resolution required for a display device that displays interference fringes by CGH (Computer Generated Hologram) is extremely high, and an enormous amount of information is required. Realizing a stereoscopic image based on a real-time hologram At present, it is technically difficult.

  In the holography technique, light waves that can be regarded as continuous information are used as an information medium to transmit information from an object. On the other hand, as a technique for generating a stereoscopic image by discretizing light waves and recreating a situation that is theoretically equivalent to a field consisting of light waves in the real world with light rays, the light ray reproduction method (also called the integral photography method) )It has been known. In the light beam reproduction method, a light beam group composed of a large number of light beams propagating in many directions is scattered in the space in advance by optical means. Next, a light ray propagating from the surface of a virtual object located at an arbitrary position is selected from the group of light rays, and the intensity or phase of the selected light ray is modulated, so that an image composed of the light rays is converted into a space. Generate. An observer can observe this image as a stereoscopic image. A stereoscopic image obtained by the ray reconstruction method is an image in which images from a plurality of directions are multiplexed at an arbitrary point, and the viewing position of an arbitrary point is the same as when a three-dimensional object is viewed in the real world. The way it looks is different.

  As an apparatus for realizing the above-described light beam reproduction method, an apparatus combining a flat display device such as a liquid crystal display device or a plasma display device with a microlens array or a pinhole array has been proposed (for example, the following). (See Patent Literature 1 to Patent Literature 7). An apparatus in which a large number of projector units are arranged is also conceivable. FIG. 22 shows a configuration example of a three-dimensional image display apparatus that realizes the light beam reproduction method using a projector unit. In this apparatus, a large number of projector units 301 are arranged in parallel in the horizontal direction and the vertical direction, and light beams having different angles are emitted from each projector unit 301. As a result, a multi-view angle image is multiplexed and reproduced at an arbitrary point in a certain cross section 302 to realize a stereoscopic image.

JP 2003-173128 A Japanese Patent Laid-Open No. 2003-161912 JP 2003-295114 A JP 2003-75771 A JP 2002-72135 A JP 2001-56450 A Japanese Patent No. 3523605

  According to the above-described light ray reproduction method, an image is obtained with light rays that are effective for focus adjustment as a visual function and binocular convergence angle adjustment, which is impossible with binocular stereoscopic image technology and multi-view stereoscopic images. Therefore, it is possible to provide a stereoscopic image with very little eye strain. In addition, since light rays are continuously emitted in a plurality of directions from the same element on the virtual object, it is possible to continuously provide a change in the image accompanying the movement of the viewpoint position.

  However, an image generated by the current light beam reproduction method lacks a sense of reality compared to an object in the real world. This is because the stereoscopic image by the current light beam reproduction method is generated by a very small amount of information, that is, a small amount of light with respect to the amount of information obtained by the observer from the object in the real world. Conceivable. In general, it is said that the human visual perception limit is about 1 minute in angular resolution, and a three-dimensional image by the current light beam reproduction method is generated by light rays that are insufficient for human vision. Therefore, in order to generate a stereoscopic image having high realism and reality of an object in the real world, it is a problem to generate an image with at least a large amount of light.

  In order to realize this, a technique capable of generating a light beam group with high spatial density is required, and it is conceivable to increase the display density of a display device such as a liquid crystal display device. Alternatively, in the case of the apparatus in which a large number of projector units 301 shown in FIG. 22 are arranged, it is conceivable that the projector units 301 are miniaturized as much as possible and arranged with high spatial density. However, a dramatic improvement in display density in current display devices is difficult due to problems of light utilization efficiency and diffraction limit. In the case of the apparatus shown in FIG. 22, it is considered difficult to arrange the projector units 301 at a high spatial density because there is a limit to downsizing the projector units 301. In any case, in order to generate a high-density light beam group, a plurality of devices are required, and the overall size of the apparatus cannot be avoided.

  Accordingly, an object of the present invention is to generate and scatter a group of light beams necessary for displaying a stereoscopic image at a high spatial density without increasing the size of the entire three-dimensional image display device. It is an object of the present invention to provide a three-dimensional image display device that makes it possible to obtain a three-dimensional image using light beams of similar quality.

In order to achieve the above object, a three-dimensional image display device according to the first aspect of the present invention comprises:
(A) a light source,
(B) Having a plurality of pixels, modulating the light from the light source by each pixel to generate a two-dimensional image, and corresponding the spatial frequency in the generated two-dimensional image to a plurality of diffraction orders generated from each pixel Light modulating means for emitting along the diffraction angle,
(C) Fourier transform image forming means for generating a Fourier transform image having a number corresponding to the plurality of diffraction orders by Fourier transforming the spatial frequency in the two-dimensional image emitted from the light modulation means;
(D) Fourier transform image selection means for selecting a Fourier transform image corresponding to a desired diffraction order among Fourier transform images generated in a number corresponding to the plurality of diffraction orders, and
(E) conjugate image forming means for forming a conjugate image of the Fourier transform image selected by the Fourier transform image selection means;
It is characterized by having.

  In the three-dimensional image display device according to the first aspect of the present invention, the conjugate image forming means is generated by the light modulation means by performing inverse Fourier transform on the Fourier transform image selected by the Fourier transform image selection means. It is preferable that an inverse Fourier transform unit for forming a real image of a two-dimensional image is included.

  In the three-dimensional image display device according to the first aspect of the present invention including the above-described preferred configuration, the light modulation means is composed of a two-dimensional spatial light modulator having a plurality of pixels arranged two-dimensionally. In this case, the two-dimensional spatial light modulator may be a liquid crystal display device (more specifically, a transmissive or reflective liquid crystal display device), or two-dimensional spatial light. It is preferable to adopt a configuration in which a movable mirror is provided in each opening of the modulator (a configuration composed of a two-dimensional MEMS in which the movable mirrors are arranged in a two-dimensional matrix). Here, the planar shape of the opening is preferably rectangular. When the planar shape of the opening is rectangular, Fraunhofer diffraction occurs, and M × N sets of diffracted light are generated as described later. That is, such an aperture forms an amplitude grating that periodically modulates the amplitude (intensity) of the incident light wave and obtains a light amount distribution that matches the light transmittance distribution of the grating.

Alternatively, in the three-dimensional image display device according to the first aspect of the present invention including the above-described preferred configuration, the light modulation means includes:
(B-1) a one-dimensional spatial light modulator that generates a one-dimensional image;
(B-2) a scanning optical system that generates a two-dimensional image by two-dimensionally developing a one-dimensional image generated by a one-dimensional spatial light modulator, and
(B-3) a grating filter that is arranged on a generation surface of a two-dimensional image and emits spatial frequencies in the generated two-dimensional image along diffraction angles corresponding to a plurality of diffraction orders;
It can be set as the form which consists of. The grating filter may be composed of an amplitude grating, or may be composed of a phase grating that modulates the phase while modulating the phase of the transmitted light amount, that is, the light amplitude (intensity) remains unchanged. .

  Furthermore, in the three-dimensional image display device according to the first aspect of the present invention including the above-described preferred configuration and configuration, the Fourier transform image forming means is formed of a lens, and the light modulation means is disposed on the front focal plane of the lens. In addition, a Fourier transform image selection means can be arranged on the rear focal plane of this lens.

  Further, in the three-dimensional image display device according to the first aspect of the present invention including the preferred configuration and form described above, the Fourier transform image selecting means has a number of opening / closing controllable openings corresponding to the plurality of diffraction orders. In this case, the Fourier transform image selection means can be formed of a liquid crystal display device (more specifically, a transmissive or reflective liquid crystal display device), and is movable. It is also possible to adopt a form of a two-dimensional type MEMS in which mirrors are arranged in a two-dimensional matrix. The Fourier transform image selection means is configured to select a Fourier transform image corresponding to a desired diffraction order by opening a desired opening in synchronization with the generation timing of the two-dimensional image by the light modulation means. It can be.

  Furthermore, in the three-dimensional image display device according to the first aspect of the present invention including the above-described preferred configuration and form, the spatial frequency in the two-dimensional image corresponds to image information using the spatial frequency of the pixel structure as the carrier frequency. It can be set as the structure to do.

A three-dimensional image display apparatus according to the second aspect of the present invention for achieving the above object is as follows:
(A) a light source,
(B) P × Q apertures (where P and Q are arbitrary positive integers) arranged in a two-dimensional matrix along the X and Y directions, and the passage and reflection of light from the light source Alternatively, a two-dimensional image is generated by controlling diffraction for each aperture, and based on the two-dimensional image, M sets (m-th to m′-th) from the m-th order along the X direction for each aperture. Where m and m ′ are integers, M is a positive integer), and N sets from the nth order to the n′th order along the Y direction (where n and n ′ are integers, N is A two-dimensional image forming apparatus that generates a total of M × N sets of diffracted light.
(C) a first lens having a two-dimensional image forming apparatus disposed on its front focal plane;
(D) A spatial filter that is arranged on the rear focal plane of the first lens and has a total of M × N open / close controllable openings, M in the X direction and N in the Y direction. ,
(E) a second lens having a spatial filter disposed on its front focal plane, and
(F) a third lens whose front focal point is located at the rear focal point of the second lens;
It is characterized by having.

  In the three-dimensional image display device according to the second aspect of the present invention, the two-dimensional image forming device includes a liquid crystal display device (more specifically, a transmissive type) having two-dimensionally arranged P × Q pixels. Or a reflection type liquid crystal display device, and each pixel may be provided with an opening, or each opening in the two-dimensional image forming apparatus is provided with a movable mirror (movable) It is preferable that the mirror is configured of a two-dimensional type MEMS disposed in each of the openings arranged in a two-dimensional matrix. Here, the planar shape of the opening is preferably rectangular. When the planar shape of the opening is rectangular, Fraunhofer diffraction occurs, and M × N sets of diffracted light are generated. That is, an amplitude grating is formed by the openings.

  In the three-dimensional image display device according to the second aspect of the present invention including the above preferable configuration and form, the spatial filter is a liquid crystal display device having M × N pixels (more specifically, a transmissive type or a reflective type). Liquid crystal display device) or a two-dimensional MEMS in which movable mirrors are arranged in a two-dimensional matrix. In addition, the spatial filter can be configured to open a desired opening in synchronization with the generation timing of the two-dimensional image by the two-dimensional image forming apparatus.

A three-dimensional image display device according to the third aspect of the present invention for achieving the above object is as follows:
(A) a light source,
(B) A one-dimensional spatial light modulator that has P pixels along the X direction and generates a one-dimensional image; two-dimensionally expands the one-dimensional image generated by the one-dimensional spatial light modulator; A scanning optical system for generating a two-dimensional image; and M sets from the m-th order to the m′-th order (where m and m ′ are integers) arranged on the generation surface of the two-dimensional image; , M is a positive integer) a two-dimensional image forming apparatus comprising diffracted light generating means for generating diffracted light,
(C) a first lens in which diffracted light generating means is disposed on the front focal plane;
(D) Arranged on the rear focal plane of the first lens, M × N in the X direction and N in the Y direction (where N is a positive integer). A spatial filter having a controllable opening,
(E) a second lens having a spatial filter disposed on its front focal plane, and
(F) a third lens whose front focal point is located at the rear focal point of the second lens;
It is characterized by having.

  In the three-dimensional image display device according to the third aspect of the present invention, the one-dimensional spatial light modulator may be configured to generate a one-dimensional image by diffracting light from the light source.

  In the three-dimensional image display device according to the third aspect of the present invention including the above preferred configuration, the spatial filter is a liquid crystal display device having M × N pixels (more specifically, a transmissive or reflective liquid crystal). A display device), or a two-dimensional MEMS in which movable mirrors are arranged in a two-dimensional matrix. In addition, the spatial filter can be configured to open a desired opening in synchronization with the generation timing of the two-dimensional image.

  Furthermore, in the three-dimensional image display device according to the third aspect of the present invention including the above-described preferable configuration, a member that causes anisotropic light diffusion (anisotropy) is further provided behind the third lens. A diffusion filter, an anisotropic diffusion sheet, or an anisotropic diffusion film) may be provided.

In the three-dimensional image display device according to the second aspect or the third aspect of the present invention, m and m ′ are integers and M is a positive integer, but the relationship between m, m ′, and M is m ≦ m ′ and M = m′−m + 1. In addition, n and n ′ are integers, and N is a positive integer, but the relationship between n, n ′, and N is n ≦ n ′ and N = n′−n + 1. The number of M and N corresponding to the total number of diffraction orders is not limited,
0 ≦ M (= m′−m + 1) ≦ 21
Preferably, for example,
5 ≦ M (= m′−m + 1) ≦ 21
Also,
0 ≦ N (= n′−n + 1) ≦ 21
Preferably, for example,
5 ≦ N (= n′−n + 1) ≦ 21
Can be illustrated. The value of M and the value of N may be equal to or different from each other. The value of | m ′ | and the value of | m | may be equal to or different from each other. The value of n ′ | may be equal to or different from the value of | n |.

  The three-dimensional image display device according to the first to third aspects of the present invention including the various preferred configurations and forms described above (hereinafter collectively referred to simply as the three-dimensional image display device of the present invention) As the light source in the above, a laser, a light emitting diode (LED), and a white light source can be given. An illumination optical system for shaping the light emitted from the light source may be disposed between the light source and the light modulation unit or the two-dimensional image forming apparatus.

  In a liquid crystal display device that constitutes a two-dimensional spatial light modulator or a two-dimensional image forming apparatus, for example, an area where a transparent first electrode and a transparent second electrode described below are overlapped and includes a liquid crystal cell is one pixel. (1 pixel). Then, by operating the liquid crystal cell as a kind of light shutter (light valve), that is, by controlling the light transmittance of each pixel, the light transmittance of light emitted from the light source is controlled as a whole. A two-dimensional image can be obtained. A rectangular opening is provided in the overlapping region of the transparent first electrode and the transparent second electrode, and light emitted from the light source passes through the opening, whereby Fraunhofer diffraction occurs for each pixel. XN sets of diffracted light are generated.

  The liquid crystal display device includes, for example, a front panel provided with a transparent first electrode, a rear panel provided with a transparent second electrode, and a liquid crystal material disposed between the front panel and the rear panel. More specifically, the front panel includes, for example, a first substrate made of, for example, a glass substrate or a silicon substrate, and a transparent first electrode (also called a common electrode, for example, ITO provided on the inner surface of the first substrate. And a polarizing film provided on the outer surface of the first substrate. Furthermore, an alignment film is formed on the transparent first electrode. On the other hand, the rear panel more specifically includes, for example, a second substrate made of a glass substrate or a silicon substrate, a switching element formed on the inner surface of the second substrate, and conduction / non-conduction by the switching element. A transparent second electrode to be controlled (also called a pixel electrode, which is made of, for example, ITO) and a polarizing film provided on the outer surface of the second substrate. An alignment film is formed on the entire surface including the transparent second electrode. Various members and liquid crystal materials constituting these transmissive liquid crystal display devices can be formed of known members and materials. Examples of the switching element include a three-terminal element such as a MOS type FET and a thin film transistor (TFT) formed on a single crystal silicon semiconductor substrate, and a two-terminal element such as an MIM element, a varistor element, and a diode. Alternatively, a liquid crystal display device having a so-called matrix electrode configuration in which a plurality of scanning electrodes extend in a first direction and a plurality of data electrodes extend in a second direction can be provided. In the transmissive liquid crystal display device, light from the light source enters from the second substrate and is emitted from the first substrate. On the other hand, in the reflective liquid crystal display device, light from the light source enters from the first substrate and is reflected by, for example, a second electrode (pixel electrode) formed on the inner surface of the second substrate, Again, it is injected from the first substrate. The opening can be obtained, for example, by forming an insulating material layer opaque to light from the light source between the transparent second electrode and the alignment film, and forming the opening in the insulating material layer. In addition, as the reflective liquid crystal display device, an LCoS (Liquid Crystal on Silicon) type can also be used.

  As a one-dimensional spatial light modulator (one-dimensional image forming apparatus), more specifically, an apparatus in which diffraction grating-light modulation elements (GLV: Grating Light Valve) are arranged one-dimensionally in an array ( Hereinafter, it may be referred to as a diffraction grating-light modulation device).

  In the three-dimensional image display device of the present invention, optical means for projecting the conjugate image formed by the conjugate image forming means may be provided, or the third lens may be provided behind the third lens. An optical means for projecting an image formed by the above may be provided.

  In the three-dimensional image display device of the present invention, when the number P × Q of the pixels (pixels) of the two-dimensional image is represented by (P, Q), specifically, as the value of (P, Q), VGA ( 640,480), S-VGA (800,600), XGA (1024,768), APRC (1152,900), S-XGA (1280,1024), U-XGA (1600,1200), HD-TV ( 1920, 1080), Q-XGA (2048, 1536), (1920, 1035), (720, 480), (1280, 960), etc. It is not limited to these values.

  In the three-dimensional image display apparatus according to the first to third aspects of the present invention, a two-dimensional image is generated by the light modulation means or the two-dimensional image forming apparatus, and the generated two-dimensional image The spatial frequency is emitted along diffraction angles corresponding to a plurality of diffraction orders generated from each pixel and the diffracted light generating means, and the spatial frequency is Fourier-transformed by the Fourier transform image forming means or the first lens, so that a plurality of diffraction orders are obtained. A Fourier transform image corresponding to a desired diffraction order among the Fourier transform images generated by the number corresponding to a plurality of diffraction orders by the Fourier transform image selecting means or the spatial filter is generated. Is selected in synchronization with the formation timing of the two-dimensional image, and the Fourier transform image is selected by the conjugate image forming means (second lens and third lens). A light beam corresponding to a plurality of diffraction orders is obtained by forming a conjugate image of the Fourier transform image selected based on the stage or the spatial filter and finally repeating the operation of reaching the observer in time series. The group can be generated and scattered in a spatially high density and distributed in a plurality of directions. As a result, the light group efficiently utilizes the light diffraction phenomenon that has not been possible in the past. Based on the light beam reproduction method, it is possible to obtain a stereoscopic image having a texture close to that of an object in the real world without increasing the size of the entire three-dimensional image display device.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

  Example 1 relates to a three-dimensional image display apparatus according to the first and second aspects of the present invention. 1 and 2 are conceptual diagrams of a three-dimensional image display apparatus according to Example 1 for monochromatic display. In FIG. 1, the optical axis is the z axis, the orthogonal coordinates in the plane orthogonal to the z axis are the x axis and the y axis, the direction parallel to the x axis is the X direction, and the direction parallel to the y axis is Y. The direction. The X direction is, for example, the horizontal direction in the 3D image display device, and the Y direction is, for example, the vertical direction in the 3D image display device. Here, FIG. 1 is a conceptual diagram of the three-dimensional image display apparatus of Example 1 in the yz plane. The conceptual diagram of the three-dimensional image display apparatus of the first embodiment in the xz plane is substantially the same as FIG. FIG. 2 is a conceptual diagram of the three-dimensional image display apparatus according to the first embodiment when viewed from an oblique direction.

  In the display of stereoscopic images using the conventional ray reconstruction method, rays that are emitted at various angles are provided in advance in order to emit a plurality of rays with the virtual object surface existing at an arbitrary position as a virtual origin. It is necessary to have a device that can do this. That is, for example, in the apparatus shown in FIG. 22, a large number (for example, M × N) of projector units 301 must be arranged in parallel in the horizontal direction and the vertical direction.

  On the other hand, in the three-dimensional image display apparatus 1 according to the first embodiment, the three-dimensional image display apparatus alone including the components shown in FIGS. 1 and 2 has a spatial density compared to the conventional technique. It is possible to generate and form a large amount of light beams that are high. The three-dimensional image display apparatus 1 according to the first embodiment is a single three-dimensional image display apparatus, and a large number (M × N) of projector units 301 shown in FIG. 22 are arranged in parallel in the horizontal direction and the vertical direction. It has a function equivalent to the device. For example, when the multi-unit method is adopted, the three-dimensional image display device 1 of the first embodiment may be provided as many as the number of divided three-dimensional images as shown in FIG. FIG. 21 illustrates an apparatus provided with 4 × 4 = 16 three-dimensional image display apparatuses 1 according to the first embodiment.

Describing along the components of the three-dimensional image display device according to the first aspect of the present invention, the three-dimensional image display device 1 of Example 1 is:
(A) Light source 10,
(B) A plurality of pixels 31 are provided, a light from a light source is modulated by each pixel 31 to generate a two-dimensional image, and a spatial frequency in the generated two-dimensional image is converted into a plurality of diffractions generated from each pixel 31. Light modulating means 30 for emitting along a diffraction angle corresponding to the order (total M × N),
(C) Fourier transform image forming means for generating a Fourier transform image having a number corresponding to the plurality of diffraction orders (total M × N) by subjecting the spatial frequency in the two-dimensional image emitted from the light modulation means 30 to Fourier transform. 40,
(D) Fourier transform image selection means 50 for selecting a Fourier transform image corresponding to a desired diffraction order among the Fourier transform images generated by the number corresponding to the plurality of diffraction orders, and
(E) conjugate image forming means 60 for forming a conjugate image of the Fourier transform image selected by the Fourier transform image selection means;
It has.

Further, the conjugate image forming unit 60 performs inverse Fourier transform on the Fourier transform image selected by the Fourier transform image selection unit 50 to form a real image of the two-dimensional image generated by the light modulation unit 30. Conversion means (specifically, a second lens L ₂ described later) is provided. Further, the Fourier transform image forming means 40 comprises a lens, the light modulation means 30 is disposed on the front focal plane of the lens, and the Fourier transform image selection means 50 is disposed on the rear focal plane of the lens. The Fourier transform image selection means 50 has a number of openings 51 that can be controlled to be opened and closed corresponding to a plurality of diffraction orders.

  Here, the spatial frequency in the two-dimensional image corresponds to image information using the spatial frequency of the pixel structure as the carrier frequency.

Further, when describing along the components of the three-dimensional image display device according to the second aspect of the present invention, the three-dimensional image display device 1 of Example 1 is:
(A) Light source 10,
(B) P × Q apertures (where P and Q are arbitrary positive integers) arranged in a two-dimensional matrix along the X and Y directions, and the light from the light source 10 A two-dimensional image is generated by controlling the passage for each aperture, and M sets from the m-th order to the m′-th order along the X direction are provided for each aperture based on the two-dimensional image (however, m and m ′ are integers, M is a positive integer), and N sets from the n-th order to the n′-th order along the Y direction (where n and n ′ are integers, N is a positive number) A two-dimensional image forming apparatus 30 that generates a total of M × N sets of diffracted light,
(C) a first lens (more specifically, a convex lens in the first embodiment) L ₁ in which the two-dimensional image forming apparatus 30 is disposed on the front focal plane thereof;
(D) M × N open / close controllable openings 51 are arranged in the rear focal plane of the first lens L ₁ and M in the X direction and N in the Y direction. A spatial filter SF,
(E) a second lens (more specifically, a convex lens in Example 1) L ₂ in which a spatial filter SF is disposed on its front focal plane, and
(F) a third lens (more specifically, a convex lens in the first embodiment) L ₃ in which the front focal point is located at the rear focal point of the second lens L ₂ ;
It has.

Here, in Example 1 or Example 2 to Example 3 described later, P = 1024, Q = 768, m = −5, m ′ = 5, M = m′−m + 1 = 11, n = −5, n ′ = 5, and N = n′−n + 1 = 11. However, it is not limited to these values. The z-axis (corresponding to the optical axis) passes through the center of each component constituting the three-dimensional image display device 1 of the first embodiment or the second to third embodiments to be described later, and displays a three-dimensional image. It is orthogonal to each component constituting the device 1. When the constituent elements of the three-dimensional image display apparatus according to the first aspect of the present invention are compared with the constituent elements of the three-dimensional image display apparatus according to the second aspect or the third aspect of the present invention, the light modulation means 30 is corresponding to the two-dimensional image forming apparatus 30, the Fourier transform image forming means 40 corresponds to the first lens L _1, the Fourier transform image selection means 50 corresponds to the spatial filter SF, the inverse Fourier transform unit and the second lens Corresponding to L ₁ , the conjugate image forming means 60 corresponds to the second lens L ₂ and the third lens L ₃ . Therefore, for convenience, the following description will be made based on the terms of the two-dimensional image forming apparatus 30, the first lens L ₁ , the spatial filter SF, the second lens L ₁ , and the third lens L ₃ .

  An illumination optical system 20 for shaping light emitted from the light source 10 is disposed between the light source 10 and the two-dimensional image forming apparatus 30. Then, the two-dimensional image forming apparatus 30 is illuminated with light (illumination light) emitted from the light source 10 and passed through the illumination optical system 20. As illumination light, for example, light obtained by shaping light from the light source 10 having high spatial coherence into parallel light by the illumination optical system 20 is used. Note that the characteristics of the illumination light and a specific configuration example for obtaining the illumination light will be described later.

  The two-dimensional image forming apparatus 30 includes a two-dimensional spatial light modulator having a plurality of pixels 31 arranged two-dimensionally, and each pixel 31 has an opening. Specifically, the two-dimensional image forming apparatus 30 or the two-dimensional spatial light modulator is two-dimensionally arranged, that is, P × Q arranged in a two-dimensional matrix along the X direction and the Y direction. It consists of a transmissive liquid crystal display device having a single pixel 31, and each pixel 31 is provided with an opening.

  One pixel 31 is composed of an overlapping region of the transparent first electrode and the transparent second electrode and including a liquid crystal cell. Then, by operating the liquid crystal cell as a kind of light shutter (light valve), that is, by controlling the light transmittance of each pixel 31, the light transmittance of the light emitted from the light source 10 is controlled, As a whole, a two-dimensional image can be obtained. In the overlapping region of the transparent first electrode and the transparent second electrode, a rectangular opening is provided. When light emitted from the light source 10 passes through the opening, Fraunhofer diffraction occurs. × N sets = 121 sets of diffracted light are generated. In other words, since the number of pixels 31 is P × Q, it can be considered that a total of (P × Q × M × N) diffracted lights are generated. In the two-dimensional image forming apparatus 30, the spatial frequency in the two-dimensional image is emitted from the two-dimensional image forming apparatus 30 along diffraction angles corresponding to a plurality of diffraction orders (total M × N) generated from each pixel 31. . The diffraction angle varies depending on the spatial frequency in the two-dimensional image.

A two-dimensional image forming apparatus 30 is arranged on the front focal plane (focal plane on the light source side) of the first lens L ₁ having a focal length f _1, and the rear focal plane (observation) of the first lens L _1. The spatial filter SF is disposed on the focal plane on the person side. The first lens L ₁ generates M × N = 121 Fourier transform images that are numbers corresponding to a plurality of diffraction orders, and these Fourier transform images are formed on the spatial filter SF. In FIG. 2, for the sake of convenience, 64 Fourier transform images are shown as dots.

Specifically, the spatial filter SF is a spatial filter capable of temporal opening and closing control for spatially and temporally filtering the Fourier transform image. More specifically, the spatial filter SF includes a number of openings 51 that can be controlled to open and close (specifically, M × N = 121) corresponding to a plurality of diffraction orders. In the spatial filter SF, one Fourier corresponding to a desired diffraction order is obtained by opening one desired opening 51 in synchronization with the generation timing of a two-dimensional image by the two-dimensional image forming apparatus 30. Select the conversion image. More specifically, the spatial filter SF is, for example, a transmissive liquid crystal display device or a reflective liquid crystal display device using a ferroelectric liquid crystal having M × N pixels, or a movable mirror is a two-dimensional matrix. It can be composed of a two-dimensional type MEMS including devices arranged in a shape. FIG. 3 shows a schematic front view of the spatial filter SF composed of a liquid crystal display device. In FIG. 3, numerals (m ₀ , n ₀ ) indicate the numbers of the openings 51 and the diffraction orders. That is, for example, a Fourier transform image having a diffraction order of m ₀ = 3 and n ₀ = 2 is incident on the (3, 2) -th opening 51.

As described above, specifically, the conjugate image forming unit 60 includes the second lens L ₂ and the third lens L ₃ . The second lens L ₂ having the focal length f ₂ performs the inverse Fourier transform on the Fourier transform image filtered by the spatial filter SF, thereby realizing the real image RI of the two-dimensional image formed by the two-dimensional image forming apparatus 30. Form. The third lens L ₃ having a focal length f ₃ forms a conjugate image CI of the Fourier transform image filtered by the spatial filter SF.

The second lens L ₂ is arranged on the front focal plane so that the spatial filter SF is positioned, and the real image RI of the two-dimensional image formed by the two-dimensional image forming apparatus 30 is formed on the rear focal plane. Are arranged to be. The magnification of the real image RI obtained here with respect to the two-dimensional image forming apparatus 30 can be changed by arbitrarily selecting the focal length f ₂ of the second lens L ₂ .

On the other hand, the third lens L ₃ is arranged such that its front focal plane coincides with the rear focal plane of the second lens L ₂ , and a conjugate image CI of the Fourier transform image is formed on the rear focal plane. Are arranged as follows. Here, since the rear focal plane of the third lens L ₃ is a conjugate plane of the spatial filter SF, it is generated by the two-dimensional image forming apparatus 30 from a portion corresponding to one opening 51 on the spatial filter SF. This is equivalent to the output of the two-dimensional image. The amount of light finally generated and output is an amount obtained by multiplying the number of pixels (P × Q) by a plurality of diffraction orders (specifically, M × N) transmitted through the optical system. Can be defined. Further, although the back focal plane of the third lens L ₃ conjugate image CI of the Fourier transform image is formed, in the back focal plane of the third lens L _3, orderly group of light beams are two-dimensionally It can be regarded as being placed. That is, as a whole, the projector unit shown in FIG. 22 is arranged on the rear focal plane of the third lens L _{3 for} a plurality of diffraction orders (specifically, M × N). Is equivalent.

As schematically shown in FIGS. 2 and 4, 11 pixels from the −5th order to the + 5th order along the X direction along the Y direction by one pixel 31 in the two-dimensional image forming apparatus 30. Eleven sets from the −5th order to the + 5′th order, M × N sets = 121 sets of diffracted light are generated. In FIG. 4, only the diffracted light of 0th order light (n ₀ = 0), ± 1st order light (n ₀ = ± 1), and ± 2nd order light (n ₀ = ± 2) is shown as a representative. As shown, higher-order diffracted light is actually generated, and a stereoscopic image is finally formed based on these diffracted light. Here, all image information (information of all pixels) of the two-dimensional image formed by the two-dimensional image forming apparatus 30 is collected in the diffracted light (light beam) of each diffraction order. A plurality of light beam groups (11 × 11 = 121 light beam groups) generated by diffraction from the same pixel on the two-dimensional image forming apparatus 30 all have the same image information at the same time. In other words, in the two-dimensional image forming apparatus 30 including a transmissive liquid crystal display device having P × Q pixels 31, the light from the light source 10 is modulated by each pixel 31 to generate a two-dimensional image. In addition, the spatial frequency in the generated two-dimensional image is emitted along diffraction angles corresponding to a plurality of diffraction orders (total M × N) generated from each pixel 31. That is, M × N types of copies of the two-dimensional image are ejected from the two-dimensional image forming apparatus 30 along diffraction angles corresponding to a plurality of diffraction orders (total M × N).

Then, the spatial frequency in the two-dimensional image in which all the image information of the two-dimensional image formed by the two-dimensional image forming apparatus 30 is aggregated is Fourier transformed by the first lens L ₁ , and a plurality of diffraction orders (total M × The number of Fourier transform images corresponding to N) is generated, and the Fourier transform images are formed on the spatial filter SF. In the first lens L ₁ , a Fourier transform image having a spatial frequency in a two-dimensional image emitted along diffraction angles corresponding to a plurality of diffraction orders is generated. Obtainable.

Here, the wavelength of light (illumination light) emitted from the light source 10 is λ (mm), the spatial frequency in the two-dimensional image formed by the two-dimensional image forming apparatus 30 is ν (lp / mm), and the first lens Assuming that the focal length of L ₁ is f ₁ (mm), light having a spatial frequency ν (Fourier transform image) at a distance Y ₁ (mm) from the optical axis on the rear focal plane of the first lens L _1. ) Appears.

Y ₁ = f ₁ · λ · ν (1)

FIG. 5 schematically shows a condensing state of the first lens L ₁ . In FIG. 5, “Y ₀ ” indicates the length in the y-axis direction of the two-dimensional image formed by the two-dimensional image forming apparatus 30, and “Y ₁ ” is formed by the two-dimensional image forming apparatus 30. The interval in the y-axis direction of the Fourier transform image on the spatial filter SF based on the two-dimensional image is shown. Further, the 0th-order diffracted light is indicated by a solid line, the first-order diffracted light is indicated by a dotted line, and the second-order diffracted light is indicated by a one-dot chain line. In other words, the diffracted light of each diffraction order, in other words, the Fourier transform image generated by the number corresponding to the diffraction order is condensed by the first lens L ₁ on different openings 51 on the spatial filter SF (FIG. 2). As described above, the number of the openings 51 is M × N = 121. The condensing angle (divergence angle after being emitted from the spatial filter SF) θ to the spatial filter SF is the same in the P × Q pixels 31 in the Fourier transform image (or diffracted light) having the same diffraction order. It is. On the spatial filter SF, an interval between Fourier transform images of adjacent diffraction orders can be obtained from Expression (1). By arbitrarily selecting the focal length f ₁ of the first lens L ₁ from the expression (1), the position of the Fourier transform image (image position on the spatial filter SF) can be changed.

In the first lens L _1, in order to transmit the spatial frequency in the two-dimensional image emitted along diffraction angles corresponding to a plurality of diffraction orders, the first lens L ₁ in accordance with the diffraction order to use It is necessary to select an aperture ratio NA, and the aperture ratios of all lenses after the first lens L ₁ are required to be equal to or higher than the aperture ratio NA of the first lens L ₁ regardless of the focal length. .

Size of the opening 51 may be the same value as the value of Y ₁ in the formula (1). As an example, the wavelength λ of the illumination light 532 nm, and the focal length f ₁ of the first lens L ₁ 50 mm, the size of one pixel 31 of the two-dimensional image forming apparatus 30 is for approximately 13Myuemu～14myuemu, Y ₁ Value Is about 2 mm. This means that a Fourier transform image corresponding to each diffraction order can be obtained at a high density of about 2 mm on the spatial filter SF. In other words, 11 × 11 = 121 Fourier transform images can be obtained on the spatial filter SF at intervals of about 2 mm in both the X direction and the Y direction.

  Here, the spatial frequency ν in the two-dimensional image formed by the two-dimensional image forming apparatus 30 is the two-dimensional image formed by the two-dimensional image forming apparatus 30 composed of P × Q pixels 31. At most, the frequency has a period composed of two consecutive pixels 31 constituting the two-dimensional image forming apparatus 30.

FIG. 6A is a schematic front view of the two-dimensional image forming apparatus 30 in a state where the spatial frequency in the two-dimensional image formed by the two-dimensional image forming apparatus 30 is the lowest. Here, the state with the lowest spatial frequency is a case where all pixels are displayed in black or white, and the spatial frequency in the two-dimensional image in this case has only a plane wave component (DC component). . FIG. 6A shows a case where white display is performed. In this case, the frequency characteristic of the light intensity of the Fourier transform image formed by the first lens L ₁ is schematically shown in FIG. 7A. The peak of the light intensity of the Fourier transform image has a frequency ν _1. Appears at intervals of.

On the other hand, FIG. 6B shows a schematic front view of the two-dimensional image forming apparatus 30 in the state where the spatial frequency in the two-dimensional image formed by the two-dimensional image forming apparatus 30 is the highest. Here, the state with the highest spatial frequency is a case where all the pixels alternately display black display and white display. In this case, the frequency characteristic of the light intensity of the Fourier transform image formed by the first lens L ₁ is schematically shown in FIG. 7B. The peak of the light intensity of the Fourier transform image has a frequency ν _2. (= ν _1/2) appears at intervals. 8A schematically shows a Fourier transform image distribution on the spatial filter SF (on the xy plane), and FIGS. 8B and 8C show the x-axis of FIG. 8A. The light intensity distribution of the Fourier transform image on (it represents with a dotted line) is shown typically. 8B shows the lowest spatial frequency component (plane wave component), and FIG. 8C shows the highest spatial frequency component.

  The planar shape of the opening 51 in the spatial filter SF may be determined based on the shape of the Fourier transform image. Furthermore, an opening 51 may be provided for each diffraction order so that the peak position of the plane wave component of the Fourier transform image is at the center. As a result, the peak of the light intensity of the Fourier transform image is located at the center position 52 of each opening 51. That is, an opening that allows all the highest positive and negative spatial frequencies in the two-dimensional image to pass through the periodic pattern of the Fourier transform image when the spatial frequency in the two-dimensional image is the lowest spatial frequency component (plane wave component). 51 may be used.

By the way, the state with the highest spatial frequency is a case where all the pixels alternately display black and white as shown in FIG. 6B. The relationship between the spatial frequency of the pixel structure in the two-dimensional image forming apparatus 30 and the spatial frequency in the two-dimensional image is as follows. That is, assuming that the aperture occupies all of the pixels, the highest spatial frequency in the two-dimensional image is (1/2) of the spatial frequency of the pixel structure. Also, if the aperture occupies a certain percentage of pixels (less than 1), the highest spatial frequency in the two-dimensional image is below (1/2) the spatial frequency of the pixel structure. Therefore, all the spatial frequencies in the two-dimensional image appear up to the half of the periodic pattern interval due to the pixel structure appearing in the spatial filter SF. For this reason, all the openings 51 can be arranged without spatially interfering with each other. That is, for example, the (3,2) th aperture 51, while the Fourier transform image having a diffraction order of _{m 0 = 3, n 0 =} 2 enters, the _{m 0 = 3, n 0 =} 2 The Fourier transform image having the diffraction order does not enter the other openings 51. Thereby, the space in the two-dimensional image formed by the two-dimensional image forming apparatus 30 in the Fourier transform image located in one opening 51 on the spatial filter SF having the independent opening 51 for each Fourier transform image. While the frequency exists, the spatial frequency in the two-dimensional image formed by the two-dimensional image forming apparatus 30 is not lost due to the spatial limitation of the opening 51. The spatial frequency of the pixel structure can be regarded as the carrier frequency, and the spatial frequency in the two-dimensional image corresponds to image information using the spatial frequency of the pixel structure as the carrier frequency.

  In the spatial filter SF, the opening / closing control of the opening 51 is performed in order to control the passage / non-passage of the M × N Fourier transform images. If the spatial filter SF is composed of, for example, a liquid crystal display device, the opening / closing control of the opening 51 can be performed by operating the liquid crystal cell as a kind of light shutter (light valve).

  Hereinafter, the timing of opening / closing control of the opening 51 in the spatial filter SF will be described.

  In the spatial filter SF, in order to select a Fourier transform image corresponding to a desired diffraction order, the opening / closing control of the opening 51 is performed in synchronization with the image output of the two-dimensional image forming apparatus 30. This operation will be described with reference to FIGS. 9, 10, and 11. FIG. 9 shows the image output timing in the two-dimensional image forming apparatus 30, and the middle stage in FIG. 9 shows the opening / closing timing of the (3, 2) -th opening 51 in the spatial filter SF. The lower part of FIG. 9 shows the opening / closing timing of the (3, 3) th opening 51.

As shown in FIG. 9, in the two-dimensional image forming apparatus 30, for example, the image “A” is displayed during time t _{1S to} t _1E (period T ₁ ), and during time t _{2S to} t _2E (period T _2). ) Is displayed as an image “B”. At this time, in the spatial filter SF, as shown in FIG. 9, the (3, 2) -th opening 51 is provided in the period T ₁ and the (3, 3) -th in the period T _2. The opening 51 is set in an open state. In this way, different image information can be added to the Fourier transform image generated as different diffraction orders in the same pixel 31 in the two-dimensional image forming apparatus 30 and generated by the first lens L ₁ . In other words, in the period T ₁ , an image “A” is displayed in a Fourier transform image having diffraction orders of m ₀ = 3 and n ₀ = 2 obtained in a certain pixel 31 in the two-dimensional image forming apparatus 30. Image information about is included. On the other hand, in the period T ₂ , the Fourier transform image having diffraction orders of m ₀ = 3 and n ₀ = 3 obtained at the same certain pixel in the two-dimensional image forming apparatus 30 is an image related to the image “B”. Contains information.

FIG. 10 schematically shows the timing of image formation and the timing of controlling the opening 51 in the two-dimensional image forming apparatus 30. In the period T ₁ , the image “A” is displayed in the two-dimensional image forming apparatus 30, and M × N Fourier transform images are collected as Fourier transform images “α” in the corresponding openings 51 of the spatial filter SF. To be lighted. In the period T ₁ , since only the (3, 2) th opening 51 is opened, only the Fourier transform image “α” having diffraction orders of m ₀ = 3 and n ₀ = 2 passes through the spatial filter SF. In the next period T ₂ , the image “B” is displayed in the two-dimensional image forming apparatus 30, and similarly, M × N Fourier transform images are displayed on the corresponding openings 51 of the spatial filter SF. It is condensed as “β”. In the period T ₂ , since only the (3, 3) th opening 51 is opened, only the Fourier transform image “β” having diffraction orders of m ₀ = 3 and n ₀ = 3 passes through the spatial filter SF. Thereafter, the opening / closing control of the opening 51 in the spatial filter SF is sequentially performed in synchronization with the image forming timing of the two-dimensional image forming apparatus 30. In FIG. 10, the opening 51 in the open state is surrounded by a solid line, and the opening 51 in the closed state is surrounded by a dotted line.

When the image formation in the two-dimensional image forming apparatus 30 and the opening / closing control of the opening 51 are performed at such timing, an image obtained as the final output of the three-dimensional image display apparatus is schematically shown in FIG. . In FIG. 11, since the image “A ′” opens only the (3, 2) -th opening 51, only the Fourier transform image “α” having diffraction orders of m ₀ = 3 and n ₀ = 2 is a space. This is an image obtained as a result of passing through the filter SF, and the image “B ′” opens only the (3, 3) -th opening 51, so that Fourier having a diffraction order of m ₀ = 3, n ₀ = 3 Only the transformed image “β” is an image obtained as a result of passing through the spatial filter SF, and the image “C ′” opens only the (4, 2) -th opening 51, so m ₀ = 4, n _0. Only the Fourier transform image “γ” having the diffraction order of = 2 is an image obtained as a result of passing through the spatial filter SF. Note that the image shown in FIG. 11 is an image viewed by an observer. In FIG. 11, for convenience, the image and the image are divided by solid lines, but the solid lines are virtual solid lines. In addition, to be exact, the image shown in FIG. 11 is not obtained at the same time, but since the image switching period is very short, it is observed as if it is simultaneously displayed to the eyes of the observer. The For example, image formation for all orders (M × N) in the two-dimensional image forming apparatus 30 and selection of one image in the spatial filter SF are performed within a display period of one frame. Further, although it is shown in a plan view in FIG. 11, what is actually observed by the observer is a stereoscopic image.

That is, as described above, from the rear focal plane of the third lens L ₃ , the two-dimensional image generated by the two-dimensional image forming apparatus 30 (for example, the images “A ′”, “ B ′ ”... Image“ C ′ ”) is output. That is, as a whole, the projector unit shown in FIG. 22 is arranged for a plurality of diffraction orders (specifically, M × N) on the rear focal plane of the third lens L ₃ . In series, an image “A ′” is output from one projector unit, an image “B ′” is output from another projector unit, and an image “C ′” is output from another projector unit. Is equivalent to For example, if the image is reproduced in time series in the two-dimensional image forming apparatus 30 based on data of a large number of images (or images created by a computer) obtained by photographing a certain object from various positions (angles). A stereoscopic image can be obtained based on these images.

If the brightness of the obtained image is different depending on the diffraction order, a neutral density filter that attenuates a bright image with respect to the darkest image is used as the rear focal plane of the _third lens L _3. Should be arranged. The same applies to Examples 2 to 3 described later.

  Moreover, the opening / closing control of the openings 51 provided in the spatial filter SF may not be performed for all the openings 51. That is, for example, the opening / closing control of every other opening 51 may be performed, or the opening / closing control of only the opening 51 located at a desired position may be performed. The same applies to Examples 2 to 3 described later.

  Configuration examples of the light source and the illumination optical system are shown in FIGS. 12 (A) to 12 (C) and FIGS. 13 (A) to 13 (B). Here, the characteristics of light (illumination light) emitted by the light source, shaped by the illumination optical system, and illuminating the two-dimensional image forming apparatus 30 will be described below using spatial coherence.

  Spatial coherence indicates the coherence of light that occurs in a cross section in an arbitrary space, and the degree thereof can be indicated by the contrast of the generated interference fringes. In the process of generating interference fringes, the interference fringes with the highest contrast are generated by interference of plane waves or spherical waves that can be optically exchanged with plane waves. This shows that the light with the highest spatial coherence is a plane wave (or spherical wave). For example, a plane wave having only one traveling direction component has the highest spatial coherence, and as the degree of spatial coherence decreases, a plurality of traveling direction components exist. Further, the distribution of the light traveling direction component is equivalent to discussing the spatial size of the light emission origin or the secondary light emission point. From the above, the spatial coherence can be discussed based on the spatial size of the light emission origin or the secondary light emission point. Spatial coherence, that is, the spatial size of the light source is a factor that determines the spatial frequency characteristics of the image in the three-dimensional image display device. When light other than light having perfect spatial coherence is used as illumination light, the contrast decreases in order from the high frequency component. Since the spatial frequency characteristics of the obtained image have different requirements depending on specific applications, various configuration methods for flexibly responding to different requirements will be described here without referring to specific numerical values.

  In the three-dimensional image display device 1 according to the first embodiment, the configuration method of the light source and the illumination optical system is different between the case where light with high spatial coherence is used as the illumination light and the case where it is not. Further, the configuration of the illumination optical system differs depending on the characteristics of the light source. Below, the combination of the structural method in a light source and an illumination optical system is demonstrated. In all cases, it is assumed that the light source is a single color or a light source close to a single color.

  FIG. 12A shows an example in which an illumination optical system 20A having a high spatial coherence as a whole is configured by a light source 10A having a high spatial coherence as a first configuration example. The light source 10A is composed of, for example, a laser. The illumination optical system 20A includes a lens 21A, a circular aperture plate 22A, and a lens 24A in order from the light source side. The circular aperture plate 22A is provided with a circular aperture 23A at the center. An aperture 23A is disposed at a condensing position in the lens 24A. The lens 24A functions as a collimator lens.

  FIG. 12B shows an example in which an illumination optical system 20B having a low spatial coherence as a whole is configured using a light source 10B having a high spatial coherence as a second configuration example. The light source 10B is composed of, for example, a laser. The illumination optical system 20B includes a lens 21B, a diffusion plate 22B, and a lens 24B in this order from the light source side. The diffusion plate 22B may be a movable diffusion plate.

  FIGS. 12C and 13A show the illumination optical system 20C having high spatial coherence as a whole using the light sources 10C and 10D having low spatial coherence as the third configuration example and the fourth configuration example. The example which comprised 20D is shown. For example, a light emitting diode (LED) or a white light source is used as the light sources 10C and 10D. The illumination optical system 20C shown in FIG. 12C includes a lens 21C, a circular aperture plate 22C, and a lens 24C in this order from the light source side. A circular aperture 23C is provided at the center of the circular aperture plate 22C. An aperture 23C is disposed at the condensing position of the lens 24C. The lens 24C functions as a collimator lens. On the other hand, in the illumination optical system 20D of FIG. 13A, the lens 21C is omitted compared to the illumination optical system 20C of FIG. 12C, and the circular aperture plate 22D, aperture 23D, and It consists of a lens 24D.

  FIG. 13B shows an example in which the illumination optical system 20E with a low spatial coherence as a whole is configured using a light source 10E with a low spatial coherence as a fifth configuration example. In addition to the light source 10E, the lens 24E is used alone.

  In each configuration example, when an illumination optical system having a high spatial coherence as a whole is constructed, the secondary emission point is reduced without depending on the light source. Further, when constructing an illumination optical system that does not have high spatial coherence as a whole, the secondary light emission point is increased without depending on the light source. The configuration examples of the light source and the illumination optical system described above can be applied to the following second to third embodiments.

As described above, according to the three-dimensional image display device 1 of the first embodiment, the spatial frequency in the two-dimensional image generated by the light modulation means (two-dimensional image forming device) 30 corresponds to a plurality of diffraction orders. The Fourier transform image obtained by being emitted along the diffraction angle and Fourier-transformed by the Fourier transform image forming means 40 (first lens L ₁ ) is obtained by the Fourier transform image selecting means 50 (spatial filter SF). Spatially and temporally filtered, and has a configuration in which a conjugate image CI of the filtered Fourier transform image is formed, so that the spatial density is high without increasing the size of the entire three-dimensional image display device. Moreover, it is possible to generate and scatter light groups in a state of being distributed in a plurality of directions. In addition, each light beam that is a constituent element of the light beam group can be independently controlled temporally and spatially. As a result, it is possible to obtain a three-dimensional image using light rays that are close to the same quality as real-world objects.

  Further, according to the three-dimensional image display device 1 of the first embodiment, since the light beam reproduction method is used, it is possible to provide a stereoscopic image that satisfies visual functions such as focus adjustment, convergence, and motion parallax. . Furthermore, according to the three-dimensional image display apparatus 1 of the first embodiment, since high-order diffracted light is efficiently used, one image output device (two-dimensional image formation) is compared with the conventional image output method. Light rays (a kind of copy of the two-dimensional image) that can be controlled by the device 30) can be obtained for a plurality of diffraction orders (ie M × N). Moreover, according to the three-dimensional image display device 1 of the first embodiment, spatial and temporal filtering is performed, so that the temporal characteristics of the three-dimensional image display device are changed to the spatial characteristics of the three-dimensional image display device. Can be converted. In addition, a stereoscopic image can be obtained without using a diffusion screen or the like. Furthermore, it is possible to provide an appropriate stereoscopic image for observation from any direction. In addition, since a group of rays can be generated and scattered at a spatially high density, a fine spatial image close to the visual recognition limit can be provided.

  Example 2 relates to a three-dimensional image display apparatus according to the first and third aspects of the present invention. A conceptual diagram of the three-dimensional image display apparatus of Example 2 is shown in FIG.

  Unlike the liquid crystal display device according to the first embodiment, the light modulation unit 130 according to the second embodiment is a one-dimensional spatial light modulator (specifically, a PD (eg, 1920) partitioned one-dimensional image). , Diffraction grating-light modulation device 201); a one-dimensional spatial light modulator (diffraction grating-light modulation device 201) formed by a two-dimensionally developed (scanned) P-dimensional one-dimensional image. ), A scanning optical system (specifically, scan mirror 205) that forms a P × Q partitioned two-dimensional image; and a spatial frequency in the generated two-dimensional image arranged on the two-dimensional image generation surface. Is provided along a diffraction angle corresponding to a plurality of diffraction orders (specifically, the total number M × N). Here, M × N sets of diffracted light are generated by the grating filter 132 for each section of the two-dimensional image formed by the scanning optical system (scan mirror 205) and partitioned into P × Q. The grating filter 132 may be composed of an amplitude grating or may be composed of a phase grating.

Alternatively, to explain along the components of the three-dimensional image display device according to the third aspect of the present invention, the three-dimensional image display device 1 of Example 2 is:
(A) Light source 10,
(B) A one-dimensional spatial light modulator (specifically, a diffraction grating-light modulation device 201) having P pixels along the X direction and generating a one-dimensional image; A scanning optical system (specifically, a scan mirror 205) that expands the generated one-dimensional image two-dimensionally to generate a two-dimensional image; and a two-dimensional image generation surface, Diffracted light generating means (specifically, grating filter 132) for generating diffracted light of M sets from the m-th order to the m'-th order (where m and m 'are integers and M is a positive integer). A two-dimensional image forming apparatus 130 comprising:
(C) a first lens (specifically, a convex lens in the second embodiment) L ₁ in which diffracted light generating means is disposed on its front focal plane;
(D) Arranged on the rear focal plane of the first lens L ₁ , M in the X direction and N in the Y direction (where N is a positive integer), a total of M × N A spatial filter SF having an opening 51 that can be controlled to open and close,
(E) a second lens (specifically, a convex lens in Example 2) L ₂ in which a spatial filter SF is disposed on the front focal plane thereof;
(F) a third lens (specifically, a convex lens in Example 2) L ₃ whose front focal point is located at the rear focal point of the second lens L ₂ ;
It has.

  Here, it is assumed that the one-dimensional image extends in the X direction. The scanning direction is the Y direction, and the two-dimensional image is formed along the X direction and the Y direction. However, alternatively, the X direction and the Y direction may be exchanged. In FIG. 14, the illumination optical system 20 is not shown.

  The one-dimensional spatial light modulator (diffraction grating-light modulation device 201) generates a one-dimensional image by diffracting light from the light source 10. More specifically, the diffraction grating-light modulation device 201 includes a diffraction grating-light modulation element (GLV) 210 arranged in a one-dimensional array. The diffraction grating-light modulation element 210 is manufactured by applying a micromachine manufacturing technique, is composed of a reflective diffraction grating, has an optical switching action, and electrically controls on / off control of light. To display the image. In the light modulation means 130, the light emitted from each of the diffraction grating-light modulation elements 210 is scanned by the scan mirror 205 formed of a galvano mirror or a polygon mirror to obtain a two-dimensional image. Accordingly, in order to display a two-dimensional image composed of P × Q (for example, 1920 × 1080) pixels (pixels), the diffraction grating-light modulation from the P (= 1920) diffraction grating-light modulation elements 210 is performed. The apparatus 201 may be configured.

It is necessary to generate diffracted light based on the two-dimensional image obtained by scanning with the scan mirror 205. Therefore, diffracted light is generated by arranging an amplitude type or phase type filter on a two-dimensionally developed surface. Specifically, the two-dimensional image obtained by scanning with the scan mirror 205 passes through the scanning lens system 131 and enters a grating filter (diffraction grating filter) 132 disposed on the generation surface of the two-dimensional image. In the lattice filter 132, M × N sets of diffracted light are generated for each section of the P × Q two-dimensional image. That is, the spatial frequency in the generated two-dimensional image is emitted from the grating filter 132 along diffraction angles corresponding to a plurality of diffraction orders generated from each section (corresponding to a pixel) of the grating filter 132. The grating filter 132 is disposed on the front focal plane of the first lens L ₁ having a focal length f ₁ .

When a one-dimensional spatial light modulator is used, since the formed image is one-dimensional, diffraction also occurs in the one-dimensional space. Therefore, an optical system intended to diffuse the obtained diffracted light in the Y direction is required. In the three-dimensional image display apparatus according to the second embodiment, the diffracted light generated in the one-dimensional direction is arranged in the two-dimensional direction downstream (observer side) from the third lens L ₃ (conjugate image forming means 60). A member (also referred to as an anisotropic diffusion filter, an anisotropic diffusion film, or an anisotropic diffusion sheet) 133 that causes anisotropic light diffusion to be diffused is disposed.

  Except for the above points, the configuration and structure of the three-dimensional image display apparatus according to the second embodiment can be the same as the configuration and structure of the three-dimensional image display apparatus described in the first embodiment. To do.

  Hereinafter, the configuration and structure of the diffraction grating-light modulation element 210 will be described.

  The arrangement of the lower electrode 212, the fixed electrode 221, the movable electrode 222, etc. constituting the diffraction grating-light modulation element 210 is schematically shown in FIG. In FIG. 15, the lower electrode 212, the fixed electrode 221, the movable electrode 222, and the support portions 214, 215, 217, and 218 are hatched for clarity.

  The diffraction grating-light modulation element 210 includes a lower electrode 212, a band-shaped (ribbon-shaped) fixed electrode 221, and a band-shaped (ribbon-shaped) movable electrode 222. The lower electrode 212 is formed on the support 211. The fixed electrode 221 is supported by the support portions 214 and 215 and supported and stretched above the lower electrode 212. Further, the movable electrode 222 is supported by support portions 217 and 218, supported and stretched above the lower electrode 212, and juxtaposed with the fixed electrode 221. In the illustrated example, one diffraction grating-light modulation element 210 is composed of three fixed electrodes 221 and three movable electrodes 222. The three movable electrodes 222 are collectively connected to the control electrode, and the control electrode is connected to a connection terminal portion (not shown). On the other hand, the three fixed electrodes 221 are collectively connected to the bias electrode. The bias electrode is common to the plurality of diffraction grating-light modulation elements 210 and is grounded via a bias electrode terminal portion (not shown). The lower electrode 212 is also common to the plurality of diffraction grating-light modulation elements 210, and is grounded via a lower electrode terminal portion (not shown).

  When a voltage is applied to the movable electrode 222 via the connection terminal portion and the control electrode and a voltage is applied to the lower electrode 212 (actually, the lower electrode 212 is in a ground state), the movable electrode 222 and the lower electrode 212 are applied. Electrostatic force (Coulomb force) is generated between The movable electrode 222 is displaced downward toward the lower electrode 212 by the electrostatic force. The state of the movable electrode 222 before displacement is shown on the left side of FIGS. 16A and 16C, and the state after displacement is shown on the right side of FIGS. 16B and 16C. Show. Based on such displacement of the movable electrode 222, a reflective diffraction grating is formed by the movable electrode 222 and the fixed electrode 221. Here, FIG. 16A is a schematic cross-sectional view of a fixed electrode or the like along the arrow BB in FIG. 15 and a schematic view of a movable electrode or the like along the arrow AA in FIG. FIG. 16 is a cross-sectional view (however, the diffraction grating-light modulation element is not in operation), and FIG. 16B is a schematic cross-sectional view of the movable electrode and the like along the arrow AA in FIG. (However, the diffraction grating-light modulation element is in operation). FIG. 16C is a schematic cross section of the fixed electrode, the movable electrode, etc. along the arrow CC in FIG. FIG.

The distance between adjacent fixed electrodes 221 is d (see FIG. 16C), the wavelength of light (incident angle: θ _i ) incident on the movable electrode 222 and the fixed electrode 221 is λ, and the diffraction angle is θ _m . Then
d [sin (θ _i ) −sin (θ _m )] = m _Dif · λ
It can be expressed as Here, m _Dif is an order and takes values of 0, ± 1, ± 2 _,.

When the height difference Δh ₁ between the top surface of the movable electrode 222 and the top surface of the fixed electrode 221 (see FIG. 16C) is (λ / 4), the light intensity of the diffracted light is the maximum value. Become.

  A conceptual diagram of such a light modulation means (two-dimensional image forming apparatus) 130 including a diffraction grating-light modulation device is shown in FIG. In other words, the light modulation means 130 of the second embodiment has a light source 10 that emits a laser, a condensing lens (not shown) that condenses light emitted from the light source 10, and light that has passed through the condensing lens is incident. Diffraction grating-light modulation device 201, lens 203 through which light emitted from diffraction grating-light modulation device 201 passes, spatial filter 204, and imaging lens that forms an image of one light beam that has passed through spatial filter 204 (not shown) I.e., a scanning mirror 205 that scans one light beam that has passed through the imaging lens.

In such a light modulation means 130, the movable electrode 222 is movable when the diffraction grating-light modulation element 210 in the state shown on the left side of FIGS. 16A and 16C is inoperative. Light reflected by the top surfaces of the electrode 222 and the fixed electrode 221 is blocked by the spatial filter 204. On the other hand, the movable electrode 222 is diffracted by the movable electrode 222 and the fixed electrode 221 when the diffraction grating-light modulation element 210 is in the state shown on the right side of FIGS. 16B and 16C. First-order (m _Dif = ± 1) diffracted light passes through the spatial filter 204. With such a configuration, light on / off control can be controlled. Further, by changing the voltage applied to the movable electrode 222, the height difference Δh ₁ between the top surface of the movable electrode 222 and the top surface of the fixed electrode 221 can be changed. As a result, the intensity of the diffracted light can be increased. The gradation control can be performed by changing.

  The third embodiment is a modification of the first embodiment. A conceptual diagram of the three-dimensional image display device of Example 3 is shown in FIG. In the three-dimensional image display apparatus of Example 1, the light transmission type two-dimensional image forming apparatus 30 was used. On the other hand, in the three-dimensional image display apparatus according to the third embodiment, a reflective light modulation means (two-dimensional image forming apparatus) 30A is used. As the reflection type light modulation means (two-dimensional image forming apparatus) 30A, for example, a reflection type liquid crystal display device or a configuration in which movable mirrors are provided in each opening (movable mirrors are arranged in a two-dimensional matrix) A configuration comprising a two-dimensional MEMS). A two-dimensional image is generated by moving / non-moving the movable mirror, and Fraunhofer diffraction is generated by the opening.

  In the three-dimensional image display device according to the third embodiment, a beam splitter 70 is provided on the z-axis (optical axis). The beam splitter 70 has a function of transmitting or reflecting light depending on the difference in polarization components. The beam splitter 70 reflects the light emitted from the light source 10 toward the reflective light modulation means (two-dimensional image forming apparatus) 30A. Further, the reflected light from the light modulation means (two-dimensional image forming apparatus) 30A is transmitted. Except for this point, the configuration and structure of the three-dimensional image display apparatus according to the third embodiment can be the same as the configuration and structure of the three-dimensional image display apparatus according to the first embodiment.

  Although the three-dimensional image display device of the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments.

In the first to third embodiments, light modulators (two-dimensional image forming apparatuses) 30 and 30A and diffracted light generators are formed on the front focal plane of the lens (first lens L ₁ ) constituting the Fourier transform image forming unit 40. The Fourier transform image selection means is arranged on the rear focal plane. However, in some cases, as a result of crosstalk occurring in the spatial frequency in the two-dimensional image, the finally obtained three-dimensional image is obtained. If the image is deteriorated but is allowed to deteriorate, the light modulating means (two-dimensional image) is positioned at a position shifted from the front focal plane of the lens (first lens L ₁ ) constituting the Fourier transform image forming means 40. Forming apparatus) 30, 30A and diffracted light generating means may be arranged, or Fourier transform image selecting means may be arranged at a position shifted from the rear focal plane. The first lens L ₁ , the second lens L ₂ , and the third lens L ₃ are not limited to convex lenses, and appropriate lenses may be selected as appropriate.

  In the first to third embodiments, it is assumed that the light source is a monochromatic or nearly monochromatic light source in all cases, but the light source is not limited to such a configuration. The wavelength band of the light source 10 may extend to a plurality of bands. However, in this case, for example, the three-dimensional image display apparatus in the first embodiment will be described as an example, as shown in FIG. 19A, the illumination optical system 20 and the light modulation means (two-dimensional image forming apparatus). It is preferable to arrange a narrow-band filter 71 that performs wavelength selection between 30 and 30, so that the wavelength band can be separated and selected, and monochromatic light can be extracted.

  Alternatively, the wavelength band of the light source 10 may extend over a wide band. However, in this case, as shown in FIG. 19B, a dichroic prism 72 and a narrow band filter for performing wavelength selection are provided between the illumination optical system 20 and the light modulation means (two-dimensional image forming apparatus) 30. It is preferable to arrange 71G. Specifically, the dichroic prism 72 reflects, for example, red light and blue light in different directions and transmits light including green light. A narrow band filter 71G for separating and selecting the green light is disposed on the light emission side including the green light in the dichroic prism 72.

  Further, as shown in FIG. 20, a narrow band filter 71G for separating and selecting green light is arranged on the emission side of the light beam including green light in the dichroic prism 72, and the red light is separated on the emission side of the light beam including red light. If the narrow band filter 71R to be selected is arranged, and the narrow band filter 71B for separating and selecting the blue light is arranged on the light emission side including the blue light, the three-dimensional image display device for displaying the three primary colors can be obtained. A light source can be configured. Three three-dimensional image display devices having such a configuration are used. Alternatively, a light source that emits red light and a three-dimensional image display device, a light source that emits green light, a three-dimensional image display device, and a blue light are emitted. By using a combination of a light source and a three-dimensional image display device and synthesizing images from the respective three-dimensional image display devices using, for example, a light combining prism, color display can be performed. A dichroic mirror can be used instead of the dichroic prism. Needless to say, the modified examples of the three-dimensional image display device described above can be applied to the second to third embodiments.

FIG. 1 is a conceptual diagram on the yz plane of the three-dimensional image display apparatus according to the first embodiment. FIG. 2 is a conceptual diagram of the three-dimensional image display device according to the first embodiment when viewed from an oblique direction. FIG. 3 is a schematic front view of an example of Fourier transform image selection means (spatial filter). FIG. 4 is a diagram schematically showing a state in which diffracted light of a plurality of diffraction orders is generated by the light modulation means (two-dimensional image forming apparatus). FIG. 5 is a diagram schematically showing a condensing state in the Fourier transform image forming means (first lens L ₁ ) and an imaging state in the Fourier transform image selecting means (spatial filter). FIGS. 6A and 6B respectively show the light modulation means (the state where the spatial frequency is the lowest and the highest state in the two-dimensional image formed by the light modulation means (two-dimensional image forming apparatus)). 1 is a schematic front view of a two-dimensional image forming apparatus. FIGS. 7A and 7B show the light of the Fourier transform image in the state where the spatial frequency is the lowest and the highest in the two-dimensional image formed by the light modulation means (two-dimensional image forming apparatus), respectively. It is a figure which shows typically the frequency characteristic of an intensity | strength. FIG. 8A is a schematic diagram showing the distribution of the Fourier transform image on the xy plane of the Fourier transform image selection means (spatial filter), and FIGS. It is a figure which shows the light intensity distribution of the Fourier-transform image on the x-axis of A). FIG. 9 is a diagram showing the formation timing of the two-dimensional image in the light modulation means (two-dimensional image forming apparatus) and the opening / closing timing of the opening of the Fourier transform image selection means (spatial filter). The two-dimensional image formation timing in the means (two-dimensional image forming apparatus) is shown, and the opening and closing timing of the opening of the Fourier transform image selection means (spatial filter) is shown in the middle and lower stages. FIG. 10 is a diagram schematically illustrating the concept of spatial filtering by Fourier transform image selection means (spatial filter) in time series. FIG. 11 is a diagram schematically showing an image obtained as a result of the spatial filtering shown in FIG. 12A, 12B, and 12C are respectively a first configuration example, a second configuration example, and a third configuration example of the light source and the illumination optical system in the three-dimensional image display apparatus of the first embodiment. It is a schematic diagram which shows. FIGS. 13A and 13B are schematic diagrams illustrating a fourth configuration example and a fifth configuration example of the light source and the illumination optical system in the three-dimensional image display apparatus according to Embodiment 1, respectively. FIG. 14 is a conceptual diagram of the three-dimensional image display apparatus according to the second embodiment. FIG. 15 is a diagram schematically showing the arrangement of the lower electrode, the fixed electrode, and the movable electrode constituting the diffraction grating-light modulation element. 16A is a schematic cross-sectional view of the fixed electrode and the like along the arrow BB in FIG. 15, and a schematic cross-sectional view of the movable electrode and the like along the arrow AA in FIG. However, the diffraction grating-light modulation element is in a non-operating state), and FIG. 16B is a schematic sectional view of the movable electrode and the like along the arrow AA in FIG. However, FIG. 16C is a schematic cross-sectional view of the fixed electrode, the movable electrode, and the like along the arrow CC in FIG. 15. . FIG. 17 is a conceptual diagram of a part of the light modulation unit (two-dimensional image forming apparatus) in the three-dimensional image display apparatus according to the second embodiment. FIG. 18 is a conceptual diagram of a part of the three-dimensional image display apparatus according to the third embodiment on the yz plane. FIGS. 19A and 19B are conceptual diagrams on a yz plane of a part of a modification of the three-dimensional image display apparatus according to the first embodiment. FIG. 20 is a conceptual diagram on a yz plane of a part of another modification of the modification of the three-dimensional image display device according to the first embodiment. FIG. 21 is a configuration diagram illustrating a multi-unit type three-dimensional image display device in which a plurality of three-dimensional image display devices according to the first embodiment are combined. FIG. 22 is a diagram illustrating a configuration example of a conventional three-dimensional image display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Three-dimensional image display apparatus 10,10A, 10B, 10C, 10D, 10E ... Light source 20,20A, 20B, 20C, 20D, 20E ... Illumination optical system, 21A, 21B, 21C, 24A, 24B, 24C, 24D, 24E ... lens, 22A, 22C, 22D ... circular aperture plate, 22B ... diffuser plate, 23A, 23C, 23D ... aperture, 30, 130 ... light Modulating means (two-dimensional image forming apparatus), 31 ... pixel, 40 ... Fourier transform image forming means, 50 ... Fourier transform image selecting means, 51 ... opening, 52 ... center of opening Position, 60 ... conjugate image forming means, 70 ... beam splitter, 71, 71R, 71G, 71B ... narrow band filter, 72 ... dichroic prism, 131 ... scanning lens system, 32... Grating filter, 133... Anisotropic diffusion filter, 201... Diffraction grating light modulator, 203... Lens, 204... Spatial filter, 205. ..Diffraction grating-light modulation element, 211... Support, 212... Lower electrode, 214, 215, 217, 218... Support, 221. L ₁ ... 1st lens, L ₂ ... 2nd lens, L ₃ ... 3rd lens, SF ... Spatial filter, RI ... Real image (inverse Fourier transform image), CI ... Conjugate images of Fourier transform images

Claims (21)

(A) a light source,
(B) Having a plurality of pixels, modulating the light from the light source by each pixel to generate a two-dimensional image, and corresponding the spatial frequency in the generated two-dimensional image to a plurality of diffraction orders generated from each pixel Light modulating means for emitting along the diffraction angle,
(C) Fourier transform image forming means for generating a Fourier transform image having a number corresponding to the plurality of diffraction orders by Fourier transforming the spatial frequency in the two-dimensional image emitted from the light modulation means;
(D) Fourier transform image selection means for selecting a Fourier transform image corresponding to a desired diffraction order among Fourier transform images generated in a number corresponding to the plurality of diffraction orders, and
(E) conjugate image forming means for forming a conjugate image of the Fourier transform image selected by the Fourier transform image selection means;
A three-dimensional image display device comprising:   The conjugate image forming unit includes an inverse Fourier transform unit that forms a real image of the two-dimensional image generated by the light modulation unit by performing an inverse Fourier transform on the Fourier transform image selected by the Fourier transform image selection unit. The three-dimensional image display device according to claim 1.   2. The three-dimensional image display device according to claim 1, wherein the light modulation means comprises a two-dimensional spatial light modulator having a plurality of pixels arranged two-dimensionally, and each pixel has an opening. .   The three-dimensional image display device according to claim 3, wherein the two-dimensional spatial light modulator comprises a liquid crystal display device.   The three-dimensional image display device according to claim 3, wherein a movable mirror is provided in each opening of the two-dimensional spatial light modulator. The light modulation means is
(B-1) a one-dimensional spatial light modulator that generates a one-dimensional image;
(B-2) a scanning optical system that generates a two-dimensional image by two-dimensionally developing a one-dimensional image generated by a one-dimensional spatial light modulator, and
(B-3) a grating filter that is arranged on a generation surface of a two-dimensional image and emits spatial frequencies in the generated two-dimensional image along diffraction angles corresponding to a plurality of diffraction orders;
The three-dimensional image display device according to claim 1, comprising: The Fourier transform image forming means comprises a lens,
A light modulation means is disposed on the front focal plane of the lens;
2. The three-dimensional image display device according to claim 1, wherein Fourier transform image selection means is disposed on the rear focal plane of the lens.   The three-dimensional image display device according to claim 1, wherein the Fourier transform image selection means has a number of opening controllable openings corresponding to the plurality of diffraction orders.   2. The three-dimensional image display device according to claim 1, wherein the Fourier transform image selection means comprises a liquid crystal display device.   In the Fourier transform image selection means, the Fourier transform image corresponding to the desired diffraction order is selected by opening the desired opening in synchronization with the generation timing of the two-dimensional image by the light modulation means. The three-dimensional image display device according to claim 9.   The three-dimensional image display device according to claim 1, wherein the spatial frequency in the two-dimensional image corresponds to image information in which the spatial frequency of the pixel structure is a carrier frequency. (A) a light source,
(B) P × Q apertures (where P and Q are arbitrary positive integers) arranged in a two-dimensional matrix along the X and Y directions, and the passage and reflection of light from the light source Alternatively, a two-dimensional image is generated by controlling diffraction for each aperture, and based on the two-dimensional image, M sets (m-th to m′-th) from the m-th order along the X direction for each aperture. Where m and m ′ are integers, M is a positive integer), and N sets from the nth order to the n′th order along the Y direction (where n and n ′ are integers, N is A two-dimensional image forming apparatus that generates a total of M × N sets of diffracted light.
(C) a first lens having a two-dimensional image forming apparatus disposed on its front focal plane;
(D) A spatial filter that is arranged on the rear focal plane of the first lens and has a total of M × N open / close controllable openings, M in the X direction and N in the Y direction. ,
(E) a second lens having a spatial filter disposed on its front focal plane, and
(F) a third lens whose front focal point is located at the rear focal point of the second lens;
A three-dimensional image display device comprising:   13. The two-dimensional image forming apparatus comprises a liquid crystal display device having P × Q pixels arranged two-dimensionally, and each pixel is provided with an opening. Dimensional image display device.   The three-dimensional image display apparatus according to claim 12, wherein each opening in the two-dimensional image forming apparatus is provided with a movable mirror.   The three-dimensional image display device according to claim 12, wherein the spatial filter is a liquid crystal display device having M × N pixels.   13. The three-dimensional image display device according to claim 12, wherein in the spatial filter, a desired opening is opened in synchronization with a generation timing of the two-dimensional image by the two-dimensional image forming device. (A) a light source,
(B) A one-dimensional spatial light modulator that has P pixels along the X direction and generates a one-dimensional image; two-dimensionally expands the one-dimensional image generated by the one-dimensional spatial light modulator; A scanning optical system for generating a two-dimensional image; and M sets from the m-th order to the m′-th order (where m and m ′ are integers) arranged on the generation surface of the two-dimensional image; , M is a positive integer) a two-dimensional image forming apparatus comprising diffracted light generating means for generating diffracted light,
(C) a first lens in which diffracted light generating means is disposed on the front focal plane;
(D) Arranged on the rear focal plane of the first lens, M × N in the X direction and N in the Y direction (where N is a positive integer). A spatial filter having a controllable opening,
(E) a second lens having a spatial filter disposed on its front focal plane, and
(F) a third lens whose front focal point is located at the rear focal point of the second lens;
A three-dimensional image display device comprising:   The three-dimensional image display device according to claim 17, wherein the one-dimensional spatial light modulator generates a one-dimensional image by diffracting light from the light source.   The three-dimensional image display device according to claim 17, wherein the spatial filter comprises a liquid crystal display device having M × N pixels.   18. The three-dimensional image display device according to claim 17, wherein the spatial filter opens a desired opening in synchronization with the generation timing of the two-dimensional image. 18. The three-dimensional image display device according to claim 17, further comprising a member that causes anisotropic light diffusion behind the third lens.