KR20150033501A - Wide viewing angle holographic display apparatus - Google Patents

Wide viewing angle holographic display apparatus Download PDF

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Publication number
KR20150033501A
KR20150033501A KR20140015041A KR20140015041A KR20150033501A KR 20150033501 A KR20150033501 A KR 20150033501A KR 20140015041 A KR20140015041 A KR 20140015041A KR 20140015041 A KR20140015041 A KR 20140015041A KR 20150033501 A KR20150033501 A KR 20150033501A
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South Korea
Prior art keywords
hologram
fourier
spatial
light modulator
spatial light
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KR20140015041A
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Korean (ko)
Inventor
채병규
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한국전자통신연구원
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Priority to US14/216,467 priority Critical patent/US20150085331A1/en
Publication of KR20150033501A publication Critical patent/KR20150033501A/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/10—Processes or apparatus for producing holograms using modulated reference beam
    • G03H1/12—Spatial modulation, e.g. ghost imaging
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/16—Processes or apparatus for producing holograms using Fourier transform
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2294—Addressing the hologram to an active spatial light modulator
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H2001/0208—Individual components other than the hologram
    • G03H2001/0224—Active addressable light modulator, i.e. Spatial Light Modulator [SLM]

Abstract

The present invention relates to a holographic display device, the holographic display device comprising an input optical unit for illuminating coherent plane waves, a light source for emitting the coherent parallel light in a plurality of directions A spatial light modulator for generating a plurality of hologram modulated diffraction beams or generating hologram modulated higher order diffracted beams by irradiating the diffracted beams in a single direction, And an imaging optical section that reproduces at least one or more other hologram stereoscopic images into one reproduction area (imaging area).

Figure P1020140015041

Description

[0001] WIDE VIEWING ANGLE HOLOGRAPHIC DISPLAY APPARATUS [0002]

The present invention relates to a holographic display device, and more particularly, to a holographic display device capable of reproducing a wide viewing angle hologram stereoscopic image.

A holographic display displays a hologram interference pattern on a spatial light modulator and reproduces a stereoscopic image by irradiating coherent parallel light. Since the viewing angle of the reproduced image is determined by the resolution of the display device, a spatial light modulator having a pixel size of less than a micrometer is required in order to secure a wide viewing area for viewing stereoscopic images. However, a liquid crystal display (LCD) or a digital micro-mirror device (DMD) panel, which is currently used as a hologram display device, is a reality in which device resolution is insufficient to obtain a sufficient viewing angle.

Recent studies for increasing the hologram image viewing angle are mainly performed by spatial or temporal multiplexing of spatial light modulators. For example, a plurality of spatial light modulators may be arranged in a curved shape to greatly increase the viewing angle. However, when a large number of holograms are used in spatio-temporal extension, a very large amount of hologram data is required and the structure of the display device is complicated.

Therefore, in order to commercialize a holographic display, it is necessary to develop a display device capable of increasing the viewing angle of a hologram reproduced image while efficiently handling hologram image data with current data processing technology.

A holographic display device according to an exemplary embodiment includes an input optical unit for irradiating a coherent plane wave in an arbitrary direction, and an in- And a spatial light modulator for generating at least one diffraction beam by optically modulating the at least one diffraction beam, and at least one hologram stereoscopic image having a different viewpoint using the generated at least one diffraction beam, into one imaging area And an imaging optical section for reproducing the light.

The in-foot optical unit according to an exemplary embodiment may include a light source for generating the coherent parallel light and a light source for irradiating coherent parallel light in a plurality of directions to the spatial light modulator.

The light source unit according to an exemplary embodiment may generate the coherent parallel light using at least one of red, green, and blue laser devices and red, green, and blue light emitting diode devices.

The light source unit may include at least one white light source device among a white light laser and a light emitting diode.

The light source irradiating unit according to an embodiment may make incident a plurality of coherent parallel lights at an arbitrary angle with respect to the vertical direction of the spatial light modulator by a time or spatial multiplexing method.

The spatial light modulator according to an exemplary embodiment may include a display panel that encodes a digital hologram interference pattern, and at least one of the phase, amplitude, and complex amplitude of the parallel light may be subjected to spatial light modulation using the display panel.

The spatial light modulator according to an exemplary embodiment of the present invention includes a spatial light modulator configured to generate a spatial light modulator having a spatial light modulator, Fourier transform data of a Fourier hologram can be generated and encoded considering the deformation of the frequency domain.

According to an embodiment, the imaging optical unit includes at least two Fourier lenses and a spatial filter, and at least one hologram stereoscopic image having a different viewpoint is reproduced in one reproduction area using the at least two Fourier lenses and the spatial filter .

The spatial light modulator according to an embodiment is located on a front focal plane of one Fourier lens among the two Fourier lenses, and the one Fourier lens uses the generated at least one diffraction beam generated in the spatial light modulator The hologram interference fringes may be arranged in a transverse direction in accordance with a progress angle of the generated at least one diffraction beam with respect to the optical axis.

According to an embodiment of the present invention, another Fourier lens among the two Fourier lenses includes at least one hologram stereoscopic image having a different viewpoint from the hologram interference fringe located at a common focal plane of the two Fourier lenses, Can be reproduced in one reproduction area within a predetermined distance from the rear focal plane of the another one of the Fourier lenses.

The spatial filter according to one embodiment is positioned on a common focal plane of the at least two Fourier lenses to remove noise in the unmodulated beam and higher order diffraction terms and selectively transmit the generated diffraction beam to produce the at least one The intensity of the diffraction beam can be adjusted.

The imaging optical unit according to an exemplary embodiment may reproduce the hologram stereoscopic image through the screen lens located on the imaging plane when the spatial light modulator is disposed at a position different from the focal distance of the Fourier lens.

The imaging optical unit may generate at least one of the time multiplexed reproduction method and the spatial multiplexed reproduction method through the RGB optical system to at least one or more hologram stereoscopic images having different viewpoints.

A holographic display device according to an embodiment includes a light source module for generating a single coherent parallel light, a spatial light modulator for spatially modulating the generated coherent parallel light to generate at least one higher order diffraction beam, And an imaging optical unit that reproduces at least one or more hologram stereoscopic images having different viewpoints in one reproduction region using the generated at least one higher order diffraction beam.

The light source module according to an exemplary embodiment may generate the coherent parallel light using at least one of red, green, and blue laser devices, and red, green, and blue light emitting diode devices.

The light source module according to one embodiment may include at least one white light source device among a white light laser and a light emitting diode.

The spatial light modulator according to an exemplary embodiment includes a display panel having a pixel structure for encoding a digital hologram interference pattern, and generates at least one higher order diffracted beam through the pixel structure of the display panel, The pixel structure can be designed in consideration of at least one of the intensity and the distribution of the diffraction beams.

According to an embodiment, the imaging optical unit includes at least two Fourier lenses and a spatial filter, and at least one hologram stereoscopic image having a different viewpoint is reproduced in one reproduction area using the at least two Fourier lenses and the spatial filter .

The spatial light modulator according to an exemplary embodiment of the present invention is located on a front focal plane of one Fourier lens among the two Fourier lenses, and the one Fourier lens uses the higher order diffracted beams generated in the spatial light modulator, Wherein the hologram interference fringe is replicated in the transverse direction according to the progress angle of the generated higher order diffraction beam with respect to the optical axis, and the other one of the two Fourier lenses Wherein at least one hologram stereoscopic image having a different viewpoint from the rear focal plane of the another Fourier lens is diffracted by using a beam diffracted from a hologram interference fringe located on a common focal plane of the two Fourier lenses, You can play in one playback area within a specified distance. The.

The imaging optical unit according to an exemplary embodiment may reproduce the hologram stereoscopic image through the screen lens located on the imaging plane when the spatial light modulator is disposed at a position different from the focal distance of the Fourier lens.

According to the present invention, a single spatial light modulator generates a diffracted beam traveling at various angles with respect to an optical axis, and transmits the diffracted beam through at least one imaging optical section to at least one hologram stereoscopic image, So that optical visualization of the hologram stereoscopic image can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a variation of a reproduction region in which a hologram stereoscopic image according to an incident angle of coherent parallel light according to an embodiment of the present invention can be viewed. FIG.
2 is a view showing a hologram stereoscopic image for a multiple diffraction beam generated from a Fourier hologram according to an embodiment of the present invention.
FIG. 3 is a view illustrating a holographic display device having a wide viewing angle by generating a plurality of diffraction beams according to an embodiment of the present invention.
4 is a view illustrating a wide viewing angle holographic display device using coherent parallel light incident at various angles according to an embodiment of the present invention
5 is a view illustrating an example of generating coherent parallel light incident at various angles in the vertical direction of the spatial light modulator according to the embodiment of the present invention.
6 is a flowchart illustrating a wide viewing angle holographic display according to an embodiment of the present invention.
FIG. 7 is a view illustrating a wide viewing angle holographic display device using a high order diffraction beam according to an embodiment of the present invention
8 is a diagram illustrating a wide viewing angle holographic display device through a screen lens using a high order diffraction beam according to an embodiment of the present invention.
9 is a diagram illustrating an example of a pixel structure of a spatial light modulator according to an embodiment of the present invention.
10 is a diagram illustrating a correlation between a higher order diffraction beam and a hologram image spectral distribution according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The terminologies used herein are terms used to properly represent preferred embodiments of the present invention, which may vary depending on the user, the intent of the operator, or the practice of the field to which the present invention belongs. Therefore, the definitions of these terms should be based on the contents throughout this specification. Like reference symbols in the drawings denote like elements.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the present invention and its advantages over the prior art will become apparent from the detailed description and claims that follow. In particular, the invention is well pointed out and distinctly claimed in the claims. The invention, however, may best be understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. Like reference numerals in the drawings denote like elements throughout the various views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a variation of a reproduction region in which a hologram stereoscopic image according to an incident angle of coherent parallel light according to an embodiment of the present invention can be viewed. FIG.

1 is a schematic diagram showing a change of a reproduced image with respect to an on-axis point hologram according to an incident angle of coherent parallel light. 1, the coherent parallel light 101 is incident on the spatial light modulator 102 indicated by the hologram at an arbitrary angle ?, And at least one hologram stereoscopic image having different viewpoints is recorded in one reproduction region 103 Can be reproduced. A coaxial wave incident perpendicular to the hologram plane can generate a hologram stereoscopic image in the reproduction region 103 located on the central axis. On the other hand, an off-axis wave produces a reproduced image at a point off the center axis.

At this time, since the direction of the diffracted light determines the area in which the hologram stereoscopic image is viewed, the observer can see the reproduced image having a different parallax, and consequently the viewing angle changes. As a result, the obliquely incident light acts as a modulated carrier wave of the off-axis holography technique, enabling the reproduction of hologram stereoscopic images having various viewpoints.

FIG. 2 is a view showing a stereoscopic reproduction image for a multiple diffraction beam generated from a Fourier hologram according to an embodiment of the present invention.

2 is a schematic diagram showing the change of the Fourier hologram reproduced image according to the parallel light incident angle, the focal distance was incident at an angle of a coherent parallel light 201, according to Figure 2 in a spatial light modulator (202) (f The hologram stereoscopic image 204 can be reproduced through the Fourier lens 203 having the spherical aberration.

2, the beam diffracted from the hologram located on the front focal plane (left side in the drawing) of the Fourier lens 203 reproduces a stereoscopic image near the rear focal plane (right side in the figure) of the lens. Light incident at an angle θ with respect to the central z-axis is made of a three-dimensional image on the shifted f 1 sin θ in the x-axis direction to the lens rear side focal point position. At this time, the stereoscopic image generates a completely deformed object image as shown in the figure, unlike the phenomenon of distortion in the Fresnel hologram reproduction. Each diffraction beam travels in the coaxial direction on the back focal plane so that a stereoscopic image having the same parallax is formed.

3 is a conceptual diagram illustrating a holographic display apparatus of a wide viewing angle by generating a plurality of diffraction beams according to an embodiment of the present invention.

Referring to FIG. 3, the holographic display device according to the present invention includes at least one hologram stereoscopic image having different viewpoints from a diffraction beam proceeding in various directions into one reproduction region 302 using the imaging optical unit 301 Optical visualization of the hologram stereoscopic image is implemented.

FIG. 4 is a schematic diagram illustrating a holographic display device according to an exemplary embodiment of the present invention. Referring to FIG. 4, the holographic display device according to an exemplary embodiment of the present invention includes coherent parallel light, Lt; RTI ID = 0.0 > direction. ≪ / RTI > Also, the holographic display device according to an embodiment of the present invention can realize a wide viewing angle hologram stereoscopic image by a method of reproducing at least one hologram stereoscopic image different in viewpoint from each diffraction beam by using the imaging optical unit.

Referring to FIG. 4, a holographic display device according to an embodiment includes an in-foot optical unit (not shown) for irradiating coherent parallel light 401 in an arbitrary direction, a coherent parallel A spatial light modulator (402) for generating a diffracted beam by spatially modulating the light, an imaging optical unit for reproducing at least one or more hologram stereoscopic images having different viewpoints in one imaging area using the generated diffraction beam, (403).

The in-foot optical unit includes a light source unit for generating coherent parallel light 401 and a light source irradiating unit for irradiating a plurality of coherent parallel lights to the spatial light modulator 402.

The light source unit may generate parallel light using red, green, and blue laser devices, or red, green, and blue light emitting diode devices. As another example, a white light source device such as a white light laser or a light emitting diode can be used for the light source portion. The light source irradiating unit provides a function of allowing a plurality of coherent parallel lights to be incident at an arbitrary angle with respect to the vertical direction of the spatial light modulator 402 in a temporal or spatial multiplexing manner.

The spatial light modulator 402 may include a display panel such as a liquid crystal display (LCD) and a digital micromirror device (DMD) having a pixel structure for encoding a digital hologram interference pattern. The spatial light modulator 402 can reproduce the hologram stereoscopic image by modulating the phase, amplitude, or complex amplitude of the coherent parallel light.

The imaging optics 403 may include at least two Fourier lenses 404,405 and a spatial filter 406. [ In addition, the imaging optical unit 403 can reproduce at least one hologram stereoscopic images having different viewpoints in one reproduction area using at least two Fourier lenses 404 and 405 and a spatial filter 406. [ For example, the imaging optical unit 403 can achieve optical visualization of a stereoscopic image by reproducing at least one or more hologram stereoscopic images 407 different in viewpoint from each diffraction beam in one reproduction area.

For example, if the spatial light modulator is located at a different position from the position along the focal length of the Fourier lens, the imaging optics 403 can reproduce the hologram stereoscopic image through the screen lens located in the imaging plane.

The Fourier lens 404 having the focal length f 1 is provided with a hologram interference pattern on the rear focal plane (right side in the figure) using a beam diffracted by the spatial light modulator 402 located on the front focal plane of the Fourier lens . The hologram pattern at this time can be replicated in the transverse direction according to the advancing angle of the diffraction beam with respect to the optical axis. For example, the hologram pattern is replicated arranged at a position spaced along the θ in the x-axis direction f 1 sin θ.

The Fourier lens 405 having the focal length f 2 can be obtained by using a beam diffracting from the hologram interference fringes located on the two fourier lens common focal planes so that at least one hologram stereoscopic image different in viewpoint And can be reproduced in one reproduction area within a predetermined distance from the rear focal plane. That is, the Fourier lens 405 can reproduce at least one hologram stereoscopic image 407 having a different viewpoint in one reproduction area near the lens rear focal plane.

The spatial filter 406 is located on the common focal plane of at least two Fourier lenses 404,405 to remove noise in the unmodulated beam and higher order diffraction terms. The spatial filter 406 may selectively transmit the generated diffraction beam to adjust the intensity of the generated diffraction beam.

The 4f imaging optical unit 403 is not limited to the above-described structure, but may be modified in various lens combinations to have the same function as the system.

In the holographic display device, the magnitude and the viewing angle of the reproduced image can be adjusted by changing the focal length of the de lens.

In the holographic display device, a sufficient viewing angle can be ensured if a seamless reproduction image having a different viewpoint is generated using a plurality of diffraction beams. Here, the Fourier lens must be able to transmit light incident at a large angle without aberration.

In the holographic display device, since the hologram stereoscopic image having different parallax can be generated by incident light incident at an arbitrary angle in the y- axis direction, the display device can realize a hologram stereoscopic image having full parallax System.

5 is a diagram illustrating an example of generating coherent parallel light incident at various angles in a vertical direction of a spatial light modulator according to an embodiment of the present invention.

Referring to FIG. 5, coherent parallel light traveling at an arbitrary angle can be produced by disposing the multi-point light source 501 in the horizontal direction on the front focal plane (left side in the drawing) of the converging lens 502.

The coherent parallel light traveling at the arbitrary angle may be formed by various methods such as a method using a galvanometer mirror.

6 is a flowchart illustrating a wide viewing angle holographic display according to an embodiment of the present invention.

Referring to FIG. 6, a hue (h, x , y ) may first be generated (step 610). Next, the Fourier transform data H ( u , v ) of the Fourier hologram, h ( x , y ), may be encoded into the spatial light modulator (step 620). In the spatial light modulator, a plurality of diffraction beams are generated from the Fourier transformed data (step 630), and a hologram interference fringe array is formed on the Fourier lens back focal plane using the generated multiple diffraction beams to reproduce the hologram stereoscopic image ( Step 640). At this time, since the back focal plane spatial frequency region is deformed with respect to the diffraction angle that does not match the paraxial approximation with respect to the optical axis traveling in the vertical direction of the spatial light modulator, the Fourier transform data of the Fourier hologram So that the distortion of the reproduced image can be eliminated.

The holographic display device according to an embodiment of the present invention may constitute an RGB optical system to implement a color moving picture by a temporal or spatial multiplexing reproduction method of a hologram. For example, the imaging optics can generate at least one of the time-multiplexed reproduction method and the spatial multiplexed reproduction method through the RGB optical system to at least one or more hologram stereoscopic images having different viewpoints.

7 is a view illustrating a wide viewing angle holographic display device using a higher order diffraction beam according to an embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a holographic display device according to another embodiment of the present invention. Referring to FIG. 7, a single coherent parallel light is incident on a spatial light modulator to generate a high-order diffracted beam traveling in various directions, And at least one hologram stereoscopic image having a different viewpoint from each diffraction beam is reproduced, thereby realizing a wide viewing angle hologram stereoscopic image.

Referring to FIG. 7, a holographic display device according to an embodiment includes a light source module (not shown) for generating a single coherent parallel light 701, modulates the generated coherent parallel light, And an imaging optical unit 703 for reproducing at least one or more hologram stereoscopic images having different viewpoints by using the generated higher order diffraction beams in one reproduction area.

The light source module may generate parallel light using at least one of red, green, and blue laser devices and red, green, and blue light emitting diode devices, or may include at least one white light source device among a white light laser and a light emitting diode .

The spatial light modulator 702 may include a display panel having a pixel structure that encodes a digital hologram interference pattern, which serves to generate a higher order diffraction term.

The spatial light modulator 702 can reproduce the hologram stereoscopic image by modulating at least one of the phase, amplitude, and complex amplitude of the coherent parallel light.

The imaging optical section 703 includes at least two Fourier lenses 704 and 705 and a spatial filter 706 and is constructed by using at least two Fourier lenses 704 and 705 and a spatial filter 706, The stereoscopic image 707 is reproduced in one reproduction area, thereby realizing optical visualization of the stereoscopic image.

The Fourier lens 704 having the focal length f 1 can form a hologram interference fringe on the rear focal plane using a beam diffracted by the spatial light modulator 702 located on the Fourier lens front focal plane (left side in the drawing). The hologram pattern at this time is replicated and arranged at a position spaced apart by f 1 sin θ in the x- axis direction according to the advancing angle of the diffraction beam with respect to the optical axis, that is, θ .

The Fourier lens 705 having the focal length f 2 is configured to focus a beam diffracted from the hologram interference fringes located on the two fourier lens common focal planes through at least one hologram stereoscopic image 707, (Right side in the drawing).

The spatial filter 706 is located on the common focal plane of the two Fourier lenses and selectively transmits the noise such as the DC term and the desired diffracted beam, and can control the intensity of the specific diffracted beam.

The imaging optical unit 703 of the first through fourth embodiments may be modified in various lens combinations to have the same function as the system described above.

The size and viewing angle of the reproduced image can be adjusted by changing the focal length of the two lenses.

In the holographic display device, a sufficiently wide viewing angle can be ensured if a seamless reproduction image having a different viewpoint is generated using higher order diffraction beams. Here, the Fourier lens must be able to transmit light incident at a large angle without aberration.

In the holographic display device, since the hologram stereoscopic image having different parallax can be generated by incident light incident at an arbitrary angle in the y- axis direction, the display device can realize a hologram stereoscopic image having full parallax System.

In the holographic display device, the spatial light modulator may Fourier transform (H ( u , v )) and encode the Fourier hologram data (h ( x , y ) The spatial light modulator also forms a hologram interference fringe array on the focal plane of the Fourier lens using the higher order diffracted beams from the Fourier transformed data. Since the rear focal plane spatial frequency region can be deformed for a very large diffraction angle, distortion of the reproduced image can be eliminated by generating Fourier transform data of the Fourier hologram considering deformation.

The holographic display device can constitute an RGB optical system to implement a color moving picture by a temporal or spatial multiplexing reproduction method of a hologram.

8 is a diagram illustrating a wide viewing angle holographic display device through a screen lens using a high order diffraction beam according to an embodiment of the present invention.

8, a holographic display device according to an exemplary embodiment of the present invention includes a light source module (not shown) for generating coherent parallel light 801, a high-order diffraction beam is generated by modulating the generated coherent parallel light, And an imaging optical unit 803 for reproducing at least one or more hologram stereoscopic images having different viewpoints using the generated higher order diffraction beams.

The light source module may generate parallel light using at least one of red, green, and blue laser devices and red, green, and blue light emitting diode devices, or may include at least one white light source device among a white light laser and a light emitting diode .

The spatial light modulator 802 may include a display panel having a pixel structure for encoding a digital hologram interference pattern, which serves to generate a higher order diffraction term.

The spatial light modulator 802 can reproduce the hologram stereoscopic image by modulating at least one of the phase, amplitude, and complex amplitude of the coherent parallel light.

The imaging optical section 803 includes a Fourier lens 804, a screen lens 805 and a spatial filter 806 so that at least one hologram stereoscopic image 807 different in viewpoint from each diffraction beam is placed at the same point Thereby realizing optical visualization of the stereoscopic image.

The Fourier lens 804 having the focal length f 1 is focussed on the Fourier lens back focal plane using a beam diffracted by the spatial light modulator 802 at a distance d 1 farther than the focal distance of the front of the Fourier lens The hologram interference fringe can be formed. At this time, the hologram pattern is replicated and arranged at a position spaced apart by f 1 sin θ in the x- axis direction according to the advancing angle, θ , of the diffraction beam with respect to the optical axis.

The screen lens 805 having the focal length f 2 plays back at least one or more hologram stereoscopic images 807 different in viewpoint from the hologram interference fringes located on the common focal plane of the two Fourier lenses at the image formation point d 2 .

The spatial filter 806 is located on a common focal plane of two Fourier lenses and selectively transmits noise such as a DC term and a desired diffracted beam, and can control intensity of a specific diffracted beam.

In the holographic display device, the magnitude of the reproduced image is determined by the magnification ( d 2 / d 1 ) with respect to the size of the spatial light modulator active panel, so that a desired size can be adjusted by a combination of two lenses having different focal lengths.

9 is a diagram illustrating an example of a spatial light modulator pixel structure according to an embodiment of the present invention.

FIG. 9 is a typical pixel structure for generating a high order diffraction beam as a spatial light modulator embodiment, showing pixel size 901 and pixel spacing 902. As shown, each pixel x as a rectangular structure is arranged in an array form in the y-axis direction. One bit of digital hologram data can be encoded into one pixel. The pixel structure can be designed in various structures in consideration of intensity and distribution of high-order diffraction beams, for example, a Blazed diffraction grating or a Damman diffraction grating structure.

10 is a graph showing a correlation between a higher order diffraction beam 1001 and a hologram image spectral distribution 1002 according to an embodiment of the present invention.

Referring to FIG. 10, the hologram image spectrum appears as a modulated form of the diffraction beam distribution. Higher-order diffracted beam is represented by a sinc function, the width of the high-order diffracted beam is shown in proportion to the spatial light modulator pixel size (Δ p). That is, the smaller the pixel size, the larger the angle can be diffracted. In order to uniformly distribute the hologram image spectrum to each diffraction beam, it is necessary that the pixel size 901 and the pixel interval 902 coincide with each other.

As a result, by using the wide viewing angle holographic display device according to the present invention, a plurality of diffracted beams can be generated through a single spatial light modulator, and a reproduced image having various viewpoints can be obtained to realize optical visualization of a hologram stereoscopic image.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it should be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described system, structure, Appropriate results can be achieved even if replaced or replaced by water.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (19)

An input optical unit for irradiating a coherent plane wave in an arbitrary direction;
A spatial light modulator for spatially modulating the coherent parallel light irradiated in the arbitrary direction to generate at least one diffraction beam; And
An imaging optical unit for reproducing at least one or more hologram stereoscopic images having different viewpoints in one imaging area using the generated at least one diffraction beam,
The holographic display device comprising: The method according to claim 1,
Said in-foot optics comprising:
A light source unit for generating the coherent parallel light; And
A light source irradiating unit for irradiating coherent parallel light in a plurality of directions to the spatial light modulator;
The holographic display device comprising: 3. The method of claim 2,
Wherein the light source unit generates the coherent collimated light using at least one of red, green, and blue laser devices and red, green, and blue light emitting diode devices. 3. The method of claim 2,
Wherein the light source unit includes at least one white light source device among a white light laser and a light emitting diode. 3. The method of claim 2,
Wherein the light source irradiating unit applies a plurality of coherent parallel lights at an arbitrary angle to a vertical direction of the spatial light modulator in a time or spatial multiplexing manner. The method according to claim 1,
Wherein the spatial light modulator includes a display panel that encodes a digital hologram interference pattern and spatially modulates at least one of the phase, amplitude, and complex amplitude of the parallel light using the display panel. The method according to claim 1,
The spatial light modulator
A Fourier transform (Fourier transform) of a Fourier hologram is performed in consideration of the deformation of a spatial frequency domain occurring at a diffraction angle that does not match a paraxial approximation with respect to an optical axis traveling in the vertical direction of the spatial light modulator from the spatial light modulator. And generates and encodes data to eliminate distortion of the reproduced image. The method according to claim 1,
Wherein the imaging optical unit includes at least two Fourier lenses and a spatial filter, and the at least one Fourier lens and the spatial filter are used to reproduce at least one hologram stereoscopic image having a different viewpoint in one reproduction area using the at least two Fourier lenses and the spatial filter. . 9. The method of claim 8,
Wherein the spatial light modulator is located on a front focal plane of one of the two Fourier lenses,
Wherein the one Fourier lens forms a hologram interference fringe on a back focal plane corresponding to the front focal plane using the generated at least one diffracted beam generated in the spatial light modulator, And wherein the diffraction grating is arranged in a transverse direction in accordance with a progress angle of the generated at least one diffraction beam. 9. The method of claim 8,
Wherein at least one of the two Fourier lenses further comprises at least one hologram stereoscopic image having a different viewpoint from the hologram interference fringe located at a common focal plane of the two Fourier lenses, In a reproduction area within a predetermined distance from the rear focal plane of the Fourier lens of the holographic recording medium. 9. The method of claim 8,
Wherein the spatial filter is positioned on a common focal plane of the at least two Fourier lenses to remove noise in the non-modulated beam and higher order diffraction terms, selectively transmit the generated at least one diffracted beam, A holographic display device for adjusting the intensity of a beam. 9. The method of claim 8,
Wherein the imaging optical unit reproduces at least one or more hologram stereoscopic images through a screen lens located on an imaging plane when the spatial light modulator is disposed at a position different from a position along the focal distance of the Fourier lens. The method according to claim 1,
Wherein the imaging optical unit applies at least one of a temporal multiplexing reproduction method and a spatial multiplexing reproduction method to at least one or more hologram stereoscopic images having different viewpoints through an RGB optical system to produce a color moving picture. A light source module for generating a single coherent parallel light;
A spatial light modulator for spatially modulating the generated coherent parallel light to generate at least one higher order diffracted beam; And
An imaging optical unit for reproducing at least one or more hologram stereoscopic images having different viewpoints in one reproduction region using the generated at least one higher order diffraction beam,
The holographic display device comprising: 15. The method of claim 14,
Wherein the light source module generates the coherent collimated light using at least one of red, green and blue laser devices and red, green and blue light emitting diode devices,
A white light laser, and a light emitting diode. 15. The method of claim 14,
Wherein the spatial light modulator comprises a display panel having a pixel structure for encoding a digital hologram interference pattern, wherein at least one or more higher order diffraction beams are generated through the pixel structure of the display panel, Wherein the pixel structure is designed by taking into account at least one of the distribution of the pixels. 15. The method of claim 14,
Wherein the imaging optical unit includes at least two Fourier lenses and a spatial filter, and the at least one Fourier lens and the spatial filter are used to reproduce at least one hologram stereoscopic image having a different viewpoint in one reproduction area using the at least two Fourier lenses and the spatial filter. . 18. The method of claim 17,
Wherein the spatial light modulator is located on a front focal plane of one of the two Fourier lenses,
Wherein the one Fourier lens forms a hologram interference fringe on a back focal plane corresponding to the front focal plane using the at least one higher order diffraction beam generated in the spatial light modulator, Is replicated in the transverse direction in accordance with the progress angle of the generated at least one higher order diffraction beam,
Wherein at least one hologram stereoscopic image having a different viewpoint from the hologram interference fringe located at a common focal plane of the two Fourier lenses is used as the another one of the two Fourier lenses, In a reproduction area within a predetermined distance from the rear focal plane of the Fourier lens of the holographic recording medium. 18. The method of claim 17,
Wherein the imaging optical unit reproduces the hologram stereoscopic image through the screen lens located on the imaging plane when the spatial light modulator is disposed at a position different from a position along the focal distance of the Fourier lens.
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