WO2015020037A1

WO2015020037A1 - Electron holography reproduction device

Info

Publication number: WO2015020037A1
Application number: PCT/JP2014/070594
Authority: WO
Inventors: 妹尾　孝憲; 光喜涌波; 保之市橋; 久幸佐々木; 健詞山本
Original assignee: 独立行政法人情報通信研究機構
Priority date: 2013-08-07
Filing date: 2014-08-05
Publication date: 2015-02-12
Also published as: JP2015031939A

Abstract

An electron holography reproduction device (1) is provided with: an enlargement optical system group (1A) for generating enlarged images of an electron hologram; a reduction optical system (1B) that reduces the enlarged images and integrates the reduced images into one electron hologram reproduction image; a spatial filter (120) which is provided with liquid crystal shutters (S1-S3) for masking high-order diffraction light; and a control means (140) for synchronously controlling the emission of light from optical fibers (F1-F3), the display of a spatial light modulator (16), and the opening and closing of the liquid crystal shutters (S1-S3). The optical axes of the optical fibers (F1-F3) are disposed at angles that are coincident with the center of the spatial light modulator (16).

Description

Electronic holography playback device

The present invention relates to an electronic holography reproducing apparatus for reproducing an electronic hologram.

Recently, display technologies capable of stereoscopic viewing using electronic holography have been proposed. This electronic holography displays interference fringes formed by interference between phase-matched reference light and object light in which the same light is scattered by an object on a hologram display device such as a liquid crystal display. In the electronic holography, the original object light is reproduced as reproduction light by using a diffraction effect generated by irradiating the hologram display device with illumination light having the same wavelength as the reference light.

This electronic holography is an ideal stereoscopic video system that satisfies all the stereoscopic factors. However, since the hologram display device requires a pixel size of about the wavelength of light, the screen is small and the viewing area is narrow at present. There's a problem.

Therefore, conventionally, an electronic holography reproducing device having a large screen and a wide viewing zone has been proposed (for example, Patent Document 1). The invention described in Patent Document 1 is obtained by arranging a plurality of hologram display modules 2 of FIG. The hologram display module 2 uses the point light source array 21 to enlarge the size and viewing area of an electronic holographic image. That is, the hologram display module 2 reflects the light from the point light source array 21 composed of the optical fibers LS1 to LS3 by the beam splitter 22 and irradiates the spatial light modulator 24 such as a liquid crystal display through the lens 23. Then, the hologram display module 2 expanded the reproduced light of the displayed hologram on the screen lens 26 through the lens 23 and the beam splitter 22, shielding the illumination light and the conjugate light at the window of the slit matrix 25. An electronic holographic image is formed. The invention described in Patent Document 1 can reproduce a large-screen electronic holographic image without gaps by arranging a plurality of hologram display modules 2.

Further, the invention described in Patent Document 1 divides the hologram display surface of the spatial light modulator 24 by the number of optical fibers LS1 to LS3 in the vertical direction in order to enlarge the horizontal viewing zone, and each has a different view. Play the hologram of the area. Furthermore, the invention described in Patent Document 1 is based on the fact that holograms in all viewing zones are formed at the window positions of the slit matrix 25 by shifting the positions of the optical fibers LS1 to LS3 in the vertical direction according to the display height of each hologram. The reproduction light can be taken out at the same height. As a result, the invention described in Patent Document 1 can expand the horizontal viewing zone.

JP 2011-17945 A

However, in the invention described in Patent Document 1, the height of the hologram in each viewing zone is a value obtained by dividing the height of the spatial light modulator 24 by the number of optical fibers. There is a problem that the vertical parallax is almost eliminated by decreasing to a value divided by the number.

Furthermore, in the invention described in Patent Document 1, as shown in FIG. 11, a magnified image of the lens 23 that converts the diffused light from the optical fibers LS1 to LS3 into parallel light and the spatial light modulator 24 is formed on the lens 26. In order to share the lens 23 to be used, it is necessary to make the distance d between the lens 23 and the spatial light modulator 24 larger than the focal length f1 of the lens 23. As a result, the invention described in Patent Document 1 has a problem that the center of illumination light from the optical fibers LS1 and LS3 is deviated from the center of the spatial light modulator 24, and an electronic holographic image with uniform brightness cannot be reproduced. is there.

Furthermore, in the invention described in Patent Document 1, as shown in FIG. 12, since the spatial filter 25 is sized to pass the hologram reproduction light in all viewing zones, high-order diffracted light in each viewing zone is shielded. There is also a problem that a ghost is generated instead and the image quality is low.

11 is optically equivalent to the hologram display module 2 of FIG. 10 (the same applies to FIG. 12). Further, f2 in FIG. 11 indicates the focal length of the lens 26.
In FIG. 12, a region 90 of reproduction light (hologram light) is indicated by hatching, and a region 91 of high-order diffracted light that is unnecessary light other than reproduction light is indicated by a broken line.

Therefore, an object of the present invention is to solve the above-described problems and provide an electronic holography reproducing device having a wide viewing zone, uniform brightness, and high image quality.

In order to solve the above-described problem, an electronic holography reproducing apparatus according to the present invention includes a plurality of magnifying optical systems that generate magnified images of divided electronic holograms obtained by dividing one electronic hologram, and each of the magnifying optical systems includes: And a reduction optical system that reduces the generated magnified image and integrates it into a single reproduced image of the electronic hologram, wherein each of the magnified optical systems is arranged at equal intervals in one direction. A light emitting means having a plurality of point light sources, a first lens for converting light emitted from the point light sources into parallel light, and a divided electronic hologram having a viewing zone corresponding to the position of the point light source as the irradiation source of the parallel light And a spatial light modulator that generates reproduction light of the divided electronic hologram by irradiating the displayed divided electronic hologram with parallel light from the first lens, and the empty electronic hologram. A reproduction light generated by the optical modulator is disposed on the imaging surface generated by passing through the first lens, and a second image having the same size as the enlarged image generated by the reproduction light imaged on the imaging surface. The reduction optical system includes a third lens that receives reproduction light from all the second lenses, and a window that passes or blocks the reproduction light emitted from the third lens for each point light source. A spatial filter provided; and a fourth lens that generates a reconstructed image of the light that has passed through the window of the spatial filter, and emits light from the point light source, and a divided electronic hologram for each viewing zone in the spatial light modulator. And control means for synchronously controlling the opening and closing of the window of the spatial filter, the spatial filter is disposed on a common focal plane of the third lens and the fourth lens, and each point light source is From the light emission side end face, the first Equal distance to the optical principal point of the lens is the focal length of the first lens, wherein the optical axis is disposed at an angle that coincides with the center of the spatial light modulator.

According to such a configuration, the electronic holography reproducing device irradiates the spatial light modulator displaying the divided electronic holograms of different viewing zones in a time division manner with a plurality of point light sources arranged in one direction. Thus, there is no need to divide the display surface of the spatial light modulator. Since the electronic holography reproducing device matches the center of the emitted light from each point light source with the center of the spatial light modulator, unevenness in brightness can be eliminated. Furthermore, the electronic holography reproducing device can also block higher-order diffracted light by a spatial filter that allows only hologram reproduction light to pass in synchronization with light emission of each point light source.

Since the electronic holography reproducing device according to the present invention does not need to divide the display surface of the spatial light modulator as in the prior art, the viewing area in the direction in which the display surface is divided is not sacrificed. Can be wide. Furthermore, the electronic holography reproducing device has no unevenness in brightness, and can maintain a reproduced image of the electronic hologram with uniform brightness. Furthermore, since the electronic holography reproducing apparatus can shield high-order diffracted light, it can reproduce high-quality electronic holograms.

In the embodiment of the present invention, (a) is a schematic configuration diagram of an electronic holography reproducing device, and (b) is a schematic configuration diagram of an enlarged optical system. In embodiment of this invention, it is explanatory drawing for demonstrating the division | segmentation of an electronic hologram. In embodiment of this invention, it is explanatory drawing for demonstrating the angle of an optical fiber. In embodiment of this invention, it is explanatory drawing for demonstrating the viewing zone angle of an enlarged image. In embodiment of this invention, it is explanatory drawing for demonstrating reproduction | regeneration of the electronic hologram of a right visual field. In embodiment of this invention, it is explanatory drawing for demonstrating reproduction | regeneration of the electronic hologram of a middle visual field. In embodiment of this invention, it is explanatory drawing for demonstrating reproduction | regeneration of the electronic hologram of a left visual field. In embodiment of this invention, it is explanatory drawing for demonstrating the synchronous control by a control means. In the modification of this invention, it is explanatory drawing for demonstrating the synchronous control by a control means. It is a schematic block diagram which shows the structure of the conventional electronic holography reproducing | regenerating apparatus. It is explanatory drawing for demonstrating the problem of the conventional electronic holography reproducing | regenerating apparatus. It is explanatory drawing for demonstrating the problem of the conventional electronic holography reproducing | regenerating apparatus.

(Embodiment)
[Configuration of electronic holography playback device]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
With reference to FIG. 1, the structure of the electronic holography reproducing | regenerating apparatus 1 which concerns on embodiment of this invention is demonstrated.

As shown in FIG. 1A, the electronic holography reproducing device 1 reproduces an electronic hologram, and includes an enlarging optical system group 1A, a reducing optical system 1B, a spatial filter 120, a hologram storage unit 130, Control means 140 and hologram reading means 150 are provided.

The magnifying optical system group 1 </ b> A generates a magnified image of a divided electronic hologram obtained by dividing one electronic hologram, and includes a plurality of magnifying optical systems 10. In the present embodiment, the magnifying optical system group 1A is composed of four magnifying optical systems 10 in total, two in the vertical and horizontal directions.
As shown in FIG. 1B, the magnifying optical system 10 includes a light emitting means 14, a first lens 15, a spatial light modulator 16, and a second lens 17, respectively.

<Division of electronic hologram>
The division of the electronic hologram will be described with reference to FIG. 2 (see FIG. 1 as appropriate).
In FIG. 2, in order to make the explanation easy to understand, an image 94 of the subject that is finally displayed by the electronic holography reproducing apparatus 1 is illustrated.

Electronic hologram 92 is equal to the magnifying optical system 10 (e.g., four) as divided hologram ₉₃ 1-93 ₄ is produced, is equally divided vertically and horizontally. Further, the divided optical holograms 93 ₁ to 93 ₄ corresponding to the arrangement positions are input to each magnifying optical system 10.

Here, in the reduction optical system 1B to be described later, the positional relationship between the divided electronic holograms 93 ₁ to 93 ₄ is reversed vertically and horizontally. it is preferable to enter the 93 _1-93 _4. For example, the upper left enlarging optical system 10 is divided electron hologram 93 ₄ lower right is input, to expand the image 94 of the subject areas included in the divided electronic hologram 93 _4. Further, for example, the lower right magnifying optical system 10 receives the upper left divided electronic hologram 93 ₁ and enlarges the subject image 94 in the region included in the divided electronic hologram 93 ₁ .

Returning to FIG. 1, the description of the configuration of the electronic holography reproducing device 1 will be continued.
The light emitting means 14 emits diffused light (emitted light) to the first lens 15, and includes an optical fiber group 11, a mirror (reflecting mirror) 12, and a beam splitter 13. The light-emitting means 14 includes a common light-emitting element that emits light of a desired wavelength (not shown) outside, causes the light-emitting element to emit light based on a timing signal described later, and transmits the light to the optical fibers F1 to F1. The light is incident on F3.

In the optical fiber group 11, the optical fibers F1 to F3 are arranged at equal intervals in the horizontal direction at an angle at which the optical axes of the optical fibers (point light sources) F1 to F3 coincide with the center of the spatial light modulator 16. . In the present embodiment, it is assumed that the optical fiber group 11 includes three optical fibers F1 to F3 so that the exit ports of the optical fibers F1 to F3 face the second lens 17 side.
Details of the angles of the optical fibers F1 to F3 will be described later.

The mirror 12 is a reflecting mirror formed in a right isosceles triangular prism shape. Specifically, the mirror 12 has a reflecting surface as an inclined surface facing the emission ports of the optical fibers F1 to F3. The mirror 12 reflects the diffused light incident in the horizontal direction from the optical fibers F1 to F3 in the vertical direction.

The beam splitter 13 reflects the diffused light reflected by the mirror 12 toward the first lens 15 and transmits the reproduction light generated by the spatial light modulator 16 to the second lens 17. Specifically, in the beam splitter 13, after forming an optical thin film on the inclined surface of one right-angle prism, the inclined surfaces of the two right-angle prisms are joined to each other. Thus, since the light emission means 14 is comprised, the electronic holography reproducing | regenerating apparatus 1 can achieve space saving.

<Angle of optical fiber>
With reference to FIG. 3, the angles of the optical fibers F1 to F3 will be described in detail (see FIG. 1 as appropriate).
FIG. 3 shows a configuration optically equivalent to the light emitting means 14, the first lens 15, and the spatial light modulator 16 of FIG.
In FIG. 3, the central axis of the spatial light modulator 16 is indicated by a long broken line, the emitted light from the optical fiber F3 is indicated by a short broken line, and the optical axis of the optical fiber F3 is indicated by a solid line. Further, in FIG. 3, the mirror 12 and the beam splitter 13 are omitted for easy understanding of the drawing, and the emission ports of the optical fibers F1 to F3 are illustrated facing the first lens 15 side.

As shown in FIG. 3, in the optical fibers F1 to F3, the distance from the light exit side end surface to the optical principal point of the first lens 15 via the mirror 12 and the beam splitter 13 is the focal length f ₁ of the first lens 15. Is equal to As a result, when the diffused light from the optical fibers F1 to F3 passes through the first lens 15, it becomes parallel light.

The light emitting side end face of the optical fiber F3 is separated from the optical axis of the first lens 15 by a distance p, and is outside the optical axis of the first lens 15 (the same position as the central axis of the spatial light modulator 16). Suppose that it is inclined by an angle θ. In this case, the center of the diffused light from the optical fiber F3 is shifted from the center of the first lens 15 by a distance l as shown in the following formula (1).

Light emitted from the light emission side end face of the optical fiber F3 and parallel to the optical axis of the first lens 15 crosses the central axis of the spatial light modulator 16 at the left focal position of the lens 15 after passing through the first lens 15. . Accordingly, the inclination of the light is expressed by the following formula (2), and all diffused light passes through the first lens 15 and becomes parallel to this light, and therefore has an inclination p / f ₁ .

The distance from the first lens 15 to the spatial light modulator 16 is d (where distance d> focal length f ₁ ). In this case, the light passing through the central axis of the spatial light modulator 16 is deviated from the optical axis of the first lens 15 as shown in Expression (3).

Therefore, the center of the parallel light can be irradiated to the center of the spatial light modulator 16 by making the expressions (1) and (3) equal. From this condition, the angle θ of the optical fiber F3 can be expressed by Expression (4).

The optical fiber F1 is symmetrical to the optical fiber F3 with respect to the central axis of the spatial light modulator 16. Therefore, like the optical fiber F3, the optical fiber F1 is tilted by the angle θ in Expression (4) outside the central axis of the spatial light modulator 16. Therefore, the center of the parallel light from the optical fiber F1 coincides with the center of the spatial light modulator 16 like the optical fiber F3. Of course, since the optical fiber F2 is located on the central axis of the spatial light modulator 16, it is not necessary to incline it. In this way, the electronic holography reproducing device 1 can uniformly irradiate the spatial light modulator 16 with the diffused light from the optical fibers F1 to F3.

Returning to FIG. 1, the description of the configuration of the electronic holography reproducing device 1 will be continued.
The first lens 15 converts diffused light from the optical fiber F1 into parallel light. The first lens 15 emits reproduction light from a spatial light modulator 16 to be described later to the second lens 17.

As described above, the first lens 15, the distance from the first lens 15 to the light emitting side end face of the optical fiber F1 ~ F3 is equal to the focal length f _1. The first lens 15, the distance d is longer than the focal length _{f 1.} In the present embodiment, the first lens 15 is a rectangular convex lens.

The spatial light modulator 16 receives hologram data from a hologram reading means 150, which will be described later, and displays a divided electronic hologram indicated by the hologram data. The spatial light modulator 16 generates reproduction light of the divided electronic hologram by irradiating the displayed divided electronic hologram with the parallel light from the first lens 15.

The spatial light modulator 16 includes a display unit 16A and a drive circuit 16B. For example, the display unit 16A is a reflective liquid crystal display that displays a divided electronic hologram. The drive circuit 16B is a drive circuit and a heat radiator for the display unit 16A, and is disposed around the display unit 16A.

The second lens 17 is disposed on the imaging surface generated by the reproduction light generated by the spatial light modulator 16 passing through the first lens 15 and is an enlarged image generated by the reproduction light imaged on the imaging surface. Is the same size lens. Here, the second lens 17 has the same size as the enlarged image in order to combine the reproduced images of the electronic hologram without any gap. In the present embodiment, the second lens 17 is a rectangular convex lens.

The reduction optical system 1B reduces the enlargement image generated by each enlargement optical system 10 and integrates it into a reproduction image of one electronic hologram, and includes a third lens 119, a spatial filter 120, and a fourth lens. 122.

<Role of reduction optical system>
The role of the reduction optical system 1B will be described in detail with reference to FIG. 4 (see FIG. 1 as appropriate).
FIG. 4 shows a configuration optically equivalent to the first lens 15, the spatial light modulator 16, and the second lens 17 in FIG.

As described above, in the spatial light modulator 16, since the drive circuit 16B is arranged around the display unit 16A, the drive circuit 16B becomes a gap and displays the divided electronic hologram on the entire surface of the spatial light modulator 16. I can't. Therefore, the electronic holography reproducing device 1 generates an enlarged image 95 by enlarging an image generated by the reproduction light from the spatial light modulator 16 so as to fill a gap when the magnifying optical system 10 is adjacently disposed. .

If the magnified image 95 is generated by the first lens 15, the viewing zone angle α of the magnified image 95 is larger than the viewing zone angle (original viewing zone angle) β of the spatial light modulator 16 as shown in FIG. Get smaller. Therefore, the reduction optical system 1B restores the combined enlarged image 95 to the original viewing zone by reducing it to the original size. As a result, the electronic holography reproducing device 1 can combine the reproduced images of the four divided electronic holograms without gaps even if the four magnifying optical systems 10 are arranged adjacent to each other, and can display one large-screen holographic image in a wide viewing area. Can be played.

Returning to FIG. 1, the description of the configuration of the electronic holography reproducing device 1 will be continued.
The third lens 119 is a lens for reducing an enlarged image from each of the magnifying optical systems 10 and combining it with a reproduced image of one electronic hologram. The third lens 119 needs to receive the reproduction light from all the second lenses 17. For this reason, the third lens 119 is preferably disposed adjacent to each second lens 17, and more preferably the distance between the optical principal points of each second lens 17 is zero. Further, the third lens 119 may have a size (diameter) that allows all the light from each of the magnifying optical systems 10 to enter when separated from each second lens 17. In the present embodiment, the third lens 119 is a circular convex lens.

The spatial filter 120 is disposed on the common focal plane of the third lens 119 and the fourth lens 122, and includes a window 121 at the center. In the window 121, liquid crystal shutters (windows) S1 to S3 that pass or shield the reproduction light emitted from the third lens 119 are provided for the respective optical fibers F1 to F3. The window 121 opens and closes the liquid crystal shutters S1 to S3 based on the timing signal.

Liquid crystal shutter S1 ~ S3 is, by the focal length _{f 3} of the third lens 119 away from the third lens 119, and are spaced apart from the fourth lens 122 by the focal length _{f 4.} The lower end positions of the liquid crystal shutters S1 to S3 are aligned with the optical axes of the third lens 119 and the fourth lens 122. The width w and the height h of the liquid crystal shutters S1 to S3 are such that an image is formed at the principal point of the third lens 119 and diffused at an angle φ / N from the principal point as shown in the following equation (5). There is equal spread of time advanced by a focal length f _3. The height h of the liquid crystal shutters S1 to S3 is about half of the width w in order to shield unnecessary light such as transmitted light and conjugate light.

As with the third lens 119, the fourth lens 122 is a lens for reducing the magnified image from each magnifying optical system 10 and combining it with a reproduced image of one electronic hologram. That is, the fourth lens 122 generates a reproduced image of the light that has passed through the windows S1 to S3 of the spatial filter 120. Here, the diameter R of the fourth lens 122 is such that the width W and height H of the display unit 16A, the number K of spatial light modulators 16 arranged vertically and horizontally, the pixel size q of the display unit 16A, and the light emitting means 14 It is determined by the emission wavelength λ of the light emitting element.

For example, when K spatial light modulators 16 are arranged vertically and horizontally, the K display portions 16A have a width KW and a height KH. The diameter R of the fourth lens 122 is, as shown in the following formula (6), the width KW and the height KH, respectively, the lateral light spread 2L × tan (2φ) and the longitudinal light. This is a value that can cover the width and height plus the spread of L × tanφ.

Note that f ₁ , f _{2, and} f ₄ represent the focal lengths of the first lens 15, the second lens 17, and the fourth lens 122, respectively. That is, N represents the magnification by the first lens 15 and the second lens 17. Here, N is the magnification ratio f2 / f1 between the first lens 15 and the second lens 17, but the width W and height H of the display unit 16A and the display unit 16A when arranged in an array. Equal to the ratio of width W ′ and height H ′.

The hologram storage means 130 is a storage device such as a memory or a hard disk that stores hologram data in advance for each of the magnifying optical system 10 and the viewing zone. In the present embodiment, the hologram storage means 130 has four magnifying optical systems 10 and three viewing zones. Therefore, in order to reproduce a reproduction image of one electronic hologram, the hologram storage means 130 includes 12 divided electronic holograms. Corresponding hologram data is stored.

As shown in FIG. 1 (a), the control unit 140 controls the emission of the optical fibers F1 to F3, the display of the spatial light modulator 16, and the opening and closing of the liquid crystal shutters S1 to S3 in synchronization. In the present embodiment, the control unit 140 outputs a timing signal indicating the timing of synchronization control to all the light emitting units 14, the spatial filter 120, and the hologram reading unit 150.
Details of the synchronization control by the control unit 140 will be described later. Further, in FIG. 1A, only one timing signal input to the light emitting means 14 is shown for easy understanding of the drawing (the same applies to the spatial light modulator 16).

The hologram reading means 150 reads out the hologram data stored in the hologram storage means 130 based on the timing signal from the control means 140 and outputs it to all the spatial light modulators 16.

<Reproduction of electronic hologram in the right viewing area>
The electronic holography reproducing device 1 reproduces electronic holograms in the right viewing area, the middle viewing area, and the left viewing area in a time division manner. With reference to FIG. 5, the reproduction of the electronic hologram in the right viewing area will be described in detail (see FIG. 1 as appropriate).

In FIG. 5, the viewing zone 90 occupied by the reproduction light generated when the optical fiber F1 irradiates the spatial light modulator 16 from the left is shown by hatching, and the region 91 occupied by the higher-order diffracted light is shown by a broken line ( The same applies to FIGS. 6 and 7. In FIG. 5, the liquid crystal shutter S1 is shown in black to indicate that it is open.

Since the spatial light modulator 16 has a periodic structure in which pixels are repeatedly arranged, when irradiated with parallel light, high-order diffracted light due to the periodic structure is generated in addition to the reproduction light of the divided electron hologram. These higher-order diffracted lights can be blocked even if a spatial filter is disposed between the first lens 15 and the second lens 17 of the magnifying optical system 10. However, this arrangement requires as many spatial filters as the number of magnifying optical systems 10, which complicates the configuration of the electronic holography reproducing device 1.

Here, in the reduction optical system 1B, all the reproduction light in the same viewing area emitted from the magnification optical system 10 passes through the same place on the common focal plane of the third lens 119 and the fourth lens 122. Therefore, the electronic holography reproducing device 1 can shield high-order diffracted light emitted from each magnification optical system 10 with a single spatial filter 120 when the spatial filter 120 is disposed at this location.

Further, the control means 140 displays the divided electronic hologram in the right viewing area on the spatial light modulator 16, the optical fiber F1 corresponding to the right viewing area emits light, and the liquid crystal shutter at the position where the reproduction light in the right viewing area passes. Synchronous control is performed so that S1 is opened and the liquid crystal shutters S2 and S3 at positions where higher-order diffracted light passes are closed.

Then, the light emitted from the right end of the right display unit 16 </ b> A out of the reproduction light in the right viewing area passes through the first lens 15 and enters the left end of the second lens 17. Then, the reproduction light in the right viewing area passes through the center of the third lens 119 and passes through the opened liquid crystal shutter S1. Thereafter, the reproduction light in the right viewing area passes through the fourth lens 122 and is reduced and becomes light from the center of the image group 96 integrated into one reproduction image.
Similarly to the above, the light emitted from the left end of the right display portion 16A passes through the first lens 15, reaches the right ends of the second lens 17 and the third lens 119, and passes through the opened liquid crystal shutter S1. Then, the reproduced light in the right viewing area reaches the left end of the fourth lens 122 and becomes light from the left end of the reproduced image group 96. Furthermore, the light emitted from the other part of the display unit 16A and the light emitted from the left display unit 16A also become the light from the reproduced image group 96.
On the other hand, high-order diffracted light is shielded by the closed liquid crystal shutters S2 and S3. In this way, the electronic holography reproducing device 1 can shield the higher-order diffracted light other than the reproduction light in the right viewing area and reproduce the reproduced image of the electronic hologram in the right viewing area.

<Reproduction of electronic hologram in the middle viewing area>
With reference to FIG. 6, the reproduction of the electronic hologram in the middle viewing area will be described in detail (see FIG. 1 as appropriate).

The control means 140 displays the divided electronic hologram of the middle viewing area on the spatial light modulator 16, the optical fiber F2 corresponding to the middle viewing area emits light, and the liquid crystal shutter S2 at the position where the reproduction light of the middle viewing area passes is opened. Synchronous control is performed so that the liquid crystal shutters S1 and S3 at positions where the next diffracted light passes are closed.

As shown in FIG. 6, the light from both ends of the display unit 16 </ b> A out of the reproduction light in the middle viewing area passes through the first lens 15 and enters both ends of the second lens 17. The reproduction light in the middle viewing area passes through the end or center of the third lens 119 and passes through the opened liquid crystal shutter S2. Thereafter, the reproduction light in the middle viewing area passes through the fourth lens 122 and is then reduced and integrated into one image group 96. Similarly, light emitted from other parts of the display unit 16A also becomes light from the reproduced image group 96. On the other hand, higher-order diffracted light is shielded by the closed liquid crystal shutters S1 and S3. In this way, the electronic holography reproducing apparatus 1 can reproduce a reproduced image of the electronic hologram in the middle viewing area by shielding higher-order diffracted light other than the reproduced light in the middle viewing area.

<Reproduction of left-side electronic hologram>
With reference to FIG. 7, the reproduction of the electronic hologram in the left viewing area will be described in detail (see FIG. 1 as appropriate).

The control unit 140 displays the divided electronic hologram of the left viewing area on the spatial light modulator 16, the optical fiber F3 corresponding to the left viewing area emits light, and the liquid crystal shutter S3 at the position where the reproduction light of the left viewing area passes. Synchronous control is performed so that the liquid crystal shutters S1 and S2 at the positions where the high-order diffracted light is opened and closed are closed.

As shown in FIG. 7, among the reproduction light in the left viewing area, light from both ends of the display unit 16 </ b> A passes through the first lens 15 and enters both ends of the second lens 17. Then, the reproduction light in the left viewing zone passes through the end or center of the third lens 119 and passes through the opened liquid crystal shutter S3. Thereafter, the reproduction light in the left viewing zone passes through the fourth lens 122 and is then reduced and integrated into one image group 96. Similarly, light emitted from other parts of the display unit 16A also becomes light from the reproduced image group 96. On the other hand, higher-order diffracted light is shielded by the closed liquid crystal shutters S1 and S2. In this way, the electronic holography reproducing apparatus 1 can shield the higher-order diffracted light other than the reproduced light in the left viewing area and reproduce the reproduced image of the electronic hologram in the left viewing area.

<Synchronous control by control means>
With reference to FIG. 8, the synchronous control by the control means 140 is demonstrated in detail (refer FIG. 1 suitably).
FIG. 8 illustrates the pulses of the timing signals S1 to S3 and the hologram data to be displayed. HR, HC, and HL of the hologram data indicate divided electronic holograms in the right viewing area, the middle viewing area, and the left viewing area, respectively. In FIG. 8, H and L of the timing signals S1 to S3 indicate the level of the level. In FIG. 8, the horizontal axis indicates the time axis.

As shown in FIG. 8, the control unit 140 outputs the high-level timing signal S1 and the low-level timing signals S2 and S3 during the time T1, in synchronization with the synchronization signal of the hologram storage unit 130. 14 light emitting elements, the spatial filter 120, and the hologram reading means 150. Then, the hologram reading means 150 reads out the divided electronic holograms in the right viewing area from the hologram storage means 130 for each of the magnifying optical systems 10 and outputs them to the spatial light modulator 16. The light emitting element of the light emitting means 14 emits light to the fiber F1 for a period of time T1. Thereby, the fiber F1 emits light, the liquid crystal shutter S1 is opened, and the spatial light modulator 16 displays the divided electronic hologram in the right viewing area. Naturally, the fibers F2 and F3 do not emit light, and the liquid crystal shutters S2 and S3 are closed.

Next, the control means 140 outputs the high level timing signal S2 and the low level timing signals S1 and S3 during the time T2, the light emitting element of the light emitting means 14, the spatial filter 120, and the hologram reading means 150. Output to. Then, the hologram reading unit 150 reads out the divided electronic holograms in the middle viewing area from the hologram storage unit 130 for each of the magnifying optical systems 10, and outputs them to the spatial light modulator 16. The light emitting element of the light emitting means 14 emits light to the fiber F2 for a period of time T2. As a result, the fiber F2 emits light, the liquid crystal shutter S2 is opened, and the spatial light modulator 16 displays the divided electronic hologram in the middle viewing area. Naturally, the fibers F1 and F3 do not emit light, and the liquid crystal shutters S1 and S3 are closed.

Next, the control means 140 outputs the high level timing signal S3 and the low level timing signals S1, S2 during the time T3, the light emitting element of the light emitting means 14, the spatial filter 120, and the hologram reading means 150. Output to. Then, the hologram reading unit 150 reads out the divided electronic holograms in the left viewing area from the hologram storage unit 130 for each of the magnifying optical systems 10 and outputs them to the spatial light modulator 16. The light emitting element of the light emitting means 14 emits light to the fiber F3 for a period of time T3. Thereby, the fiber F3 emits light, the liquid crystal shutter S3 is opened, and the spatial light modulator 16 displays the divided electronic hologram in the left viewing area. Naturally, the fibers F1 and F2 do not emit light, and the liquid crystal shutters S1 and S2 are closed.

[Action / Effect]
Since conventional holographic displays use light interference in electronic holography, the pixel size must be about the wavelength of light, making it difficult to produce a large-screen display. Furthermore, in the conventional stereoscopic display, when the usable pixel size is larger than the wavelength of light, the power to diffract light becomes weak, and it is difficult to ensure a wide viewing area.

The electronic holography reproducing device 1 exhibits its effect most when applied to a stereoscopic display using electronic holography, which is an ideal stereoscopic video system. Specifically, the electronic holography reproducing device 1 can arrange a plurality of spatial light modulators 16 having a small number of pixels adjacent to each other so as to combine the reproduced images of the electronic hologram without any gap, and can reproduce a large-screen holographic image. . Furthermore, the electronic holography reproducing device 1 expands the viewing zone at a magnification equal to the number of the optical fibers F1 to F3 by irradiating the spatial light modulators 16 in time division with the optical fibers F1 to F3 having different positions and angles. be able to.

Furthermore, since the electronic holography reproducing device 1 has the optical fibers F1 and F3 directed outward with respect to the central axis of the spatial light modulator 16, the center of the emitted light from the optical fibers F1 to F3 is set to the center of the spatial light modulator 16. And uneven brightness in each viewing zone can be eliminated. Furthermore, since the electronic holography reproducing apparatus 1 can shield high-order diffracted light generated in each spatial light modulator 16 by the single spatial filter 120, it can reproduce a high-quality electronic holographic image without ghosting. .

(Modification)
The electronic holography reproducing device 1 is not limited to the above-described embodiment, and can be modified without departing from the spirit thereof.
As shown in FIG. 9, the electronic holography reproducing device 1 can be made full color by switching the emission wavelengths (R, G, B) of the light emitting elements of the light emitting means 14 in a time division manner. As shown in FIG. 9, the control unit 140 extracts a synchronization signal (V-sync) from the HD-SDI signal of the hologram data stored in the hologram storage unit 140. Then, the control unit 140 performs synchronization control using timing signals S1 to S3 corresponding to three rounds of the extracted synchronization signal. For example, in FIG. 9, t1 is about 1/60 (sec) and t2 is 150 (μsec).

In the above-described embodiment, it has been described that two magnifying optical systems 10 are provided vertically and horizontally, but the number is not limited. For example, three or four magnifying optical systems 10 may be provided vertically and horizontally. Further, the magnifying optical system 10 may have different numbers in the vertical and horizontal directions.

In the above-described embodiment, it has been described that time division is performed in the right viewing area, the middle viewing area, and the left viewing area, but the present invention is not limited thereto.
For example, the electronic holography reproducing device 1 may perform time division in five viewing zones such as a deep right viewing zone, a shallow right viewing zone, a middle viewing zone, a shallow left viewing zone, and a deep left viewing zone. In this case, the electronic holography reproducing device 1 arranges one optical fiber on the central axis of the spatial light modulator 16 and symmetrically separates the two optical fibers from the central axis of the spatial light modulator 16 at equal intervals. Deploy. Each spatial light modulator 16 displays a divided electronic hologram of a deep right viewing area, a shallow right viewing area, a middle viewing area, a shallow left viewing area, and a deep left viewing area. The spatial filter 120 includes five liquid crystal shutters corresponding to the five optical fibers. Further, the control unit 140 synchronously controls the light emission of the five optical fibers, the display of the spatial light modulator 16, and the opening and closing of the five liquid crystal shutters. In this way, the electronic holography reproduction device 1 can further enlarge the viewing zone.

DESCRIPTION OF SYMBOLS 1 Electronic holography reproducing | regenerating apparatus 1A Magnification optical system group 1B Reduction optical system 10 Magnification optical system 11 Optical fiber group 12 Mirror (reflection mirror)
13 beam splitter 14 light emitting means 15 first lens 16 spatial light modulator 17 second lens 119 third lens 120 spatial filter 121 window 122 fourth lens 130 hologram storage means 140 control means 150 hologram reading means F1 to F3 optical fiber ( Point light source)
S1 to S3 Liquid crystal shutter (window)

Claims

A plurality of magnifying optical systems that generate magnified images of divided electronic holograms obtained by dividing one electronic hologram, and a magnified image generated by each of the magnifying optical systems is reduced to a reproduced image of one electronic hologram. An electronic holography reproducing device comprising a reduction optical system to be integrated,
Each of the magnifying optical systems
A light emitting means having a plurality of point light sources arranged at equal intervals in one direction;
A first lens for converting light emitted from the point light source into parallel light;
A divided electron hologram in a viewing zone corresponding to the position of the point light source that is the irradiation source of the parallel light is displayed, and the divided electron hologram is irradiated with parallel light from the first lens, whereby the divided electron is irradiated. A spatial light modulator for generating hologram reproduction light;
The reproduction light generated by the spatial light modulator is disposed on the imaging surface generated by passing through the first lens, and has the same size as the enlarged image generated by the reproduction light imaged on the imaging surface. A second lens,
The reduction optical system includes:
A third lens from which reproduction light is incident from all the second lenses;
A spatial filter provided with a window for passing or blocking the reproduction light emitted from the third lens for each point light source;
A fourth lens that generates a reconstructed image of the light that has passed through the window of the spatial filter,
Control means for synchronously controlling light emission of the point light source, display of a divided electronic hologram in each viewing zone in the spatial light modulator, and opening and closing of the window of the spatial filter,
The spatial filter is disposed on a common focal plane of the third lens and the fourth lens;
Each of the point light sources is disposed at an angle such that the distance from the light emitting side end surface to the optical principal point of the first lens is equal to the focal length of the first lens, and the optical axis coincides with the center of the spatial light modulator. An electronic holography reproducing device characterized by that.
The light emitting means includes an angle θ between the optical axis of the point light source and the central axis of the spatial light modulator, a distance d from the first lens to the spatial light modulator, and a focal length f of the first lens. The electronic holography reproducing device according to claim 1, wherein the electronic holographic reproducing device is represented by an equation (4) including 1 and an arrangement interval p of the point light sources.
The control means sequentially emits one point light source for each of the magnifying optical systems, causes the spatial light modulator to display a divided electronic hologram of a viewing zone corresponding to the position of the emitted point light source, and 3. The electronic holography reproducing apparatus according to claim 1, wherein a window is opened / closed in the spatial filter so as to allow only the reproducing light generated by the optical modulator to pass.
The light emitting means includes
The point light sources are arranged in a horizontal direction;
A reflecting mirror that reflects light emitted from the point light source in a vertical direction;
A beam splitter that reflects the outgoing light reflected by the reflecting mirror toward the first lens and transmits the reproduction light generated by the spatial light modulator to the second lens; The electronic holography reproducing device according to claim 1.
The light emitting means includes
The point light sources are arranged in a horizontal direction;
A reflecting mirror that reflects light emitted from the point light source in a vertical direction;
A beam splitter that reflects the outgoing light reflected by the reflecting mirror toward the first lens and transmits the reproduction light generated by the spatial light modulator to the second lens; The electronic holography reproducing device according to claim 3.