KR20010087984A - Multiviewpoint Autostereoscopic 3D Display System based on Volume Holographic Optical Element(VHOE) - Google Patents

Abstract

PURPOSE: A multiviewpoint autostereoscopic 3D display system based on VHOE(volume holographic optical element) is provided to synthesize MSI(multiplexed stripe images) in realtime and to realize an ultra fast realtime random access. CONSTITUTION: A beam splitter(20) splits a laser beam from a laser into a reference beam and an object beam. A first SLM(spatial light modulator)(24) is positioned on an optical path of the reference beam, forms a mixture shape of multiviewpoint images by the radiation due to the reference beam to form spatial multiplexed strip pattern optical modulated images under the state that input patterns of light strength modulation shape corresponding to MSI are formed for display with parallax barrier shape. A second SLM(25) is positioned on an optical path of the object beam, forms a mixture shape of multiviewpoint images by the beam radiation to perform spatial multiplexing for the mixed shape under the state that lattice shape patterns corresponding to the multiviewpoint images are formed for display with parallel barrier shape. A first reflector(31) is positioned between the beam splitter(20) a first focusing lens(41) for orienting the beam toward the beam splitter. A second reflector(32) is positioned between a second focusing lens(42) and an optical refraction recording medium(50). A third reflector is rotatably positioned between the second SLM(25) and a third focusing lens group(43,44). A rotator(60) for the third reflector provides rotation force for rotating the third reflector(33). A phase converter(23) converts vertical deflection wave from the beam splitter(20) and the laser into horizontal deflection waves.

Description

Multiviewpoint Autostereoscopic 3D Display System based on Volume Holographic Optical Element (VHOE)}

The present invention relates to a 3D stereoscopic image recording / reproducing apparatus, and more particularly, to a plane reference wave and a planar object wave of a strip pattern multiplexed for recording / reproducing 3D stereoscopic images based on angular multiplexing and spatial multiplexing. And a lattice pattern recorded on an optical refraction recording medium, and a volume holographic optical device capable of effectively reproducing multi-dimensional stereoscopic 3D stereoscopic images by injecting an object wave containing a Bragg matching condition and containing image information. The present invention relates to a multiviewpoint autostereoscopic 3D display system based on volume holographic optical element (VHOE).

The present invention relates to holographic storage technology and multi-eye stereoscopic image display technology. Briefly, a general knowledge of holographic storage technology using a photorefraction effect to help the understanding of the present invention is briefly described. Refers to a change in the refractive index caused by light in the refractive recording medium, which is represented by a grating of refractive index corresponding to the interference pattern due to two interfering light waves in the photorefractive crystal. The basic mechanism of the photorefractive effect is that light is incident on the photorefraction recording medium, followed by photoionization, diffusion, recombination, space charge formation, and electric field formation. The information is recorded as the change of. In other words, the charges generated by the photoionization phenomenon have a non-uniform density, resulting in a non-uniform space charge distribution through diffusion or drift. This spatial charge distribution forms an internal electric field within the crystal, which can store input information by locally changing the refractive index of the material by the electro-optic effect. For reference, the Pockel effect refers to a phenomenon in which the refractive index of light changes in proportion to the intensity of an electric field applied thereto in transparent crystals. The three-dimensional image technology using binocular disparity among three technologies for displaying three-dimensional stereoscopic images separates and presents two two-dimensional images having binocular disparity separately from the left eye and the right eye to stereoscopically create a space having a sense of depth before and after the display plane. It can be reproduced.

Conventionally, optical recording technology known as volume holography has been analyzed as one of the next generation information storage technologies because it can store a large amount of data in an optical refraction recording medium having a size equivalent to a sugar cube, and can access ultra-fast parallel random access of the stored information.

In order for the input data to be stored in the form of a lattice pattern in the crystal, the data is first made into an input pattern in the form of light intensity modulation in a spatial light modulator such as a liquid crystal-spatial light modulator (LC-SLM).

For example, a blue laser beam is irradiated through LC-SLM page data such as a crossword puzle pattern and imaged by a lens to produce an optical modulated image. When the optical modulation image meets a reference wave aligned at a plurality of angles (or wavelengths, phase codes) and an optical refraction recording medium, thousands of pages of hologram data are multiplexed and recorded at high density.

After this recording process, the data of a specific page can be reproduced holographically by injecting the reference wave again at the same angle (or wavelength, phase code) as the reference wave used at the time of recording. That is, when passing through the diffraction grating formed in the optical refraction recording medium, the reference wave is diffracted in the direction of reproducing the image of the information on the original page.

The reproduced image is incident on an image sensor such as a charge coupled device (CCD) to read all the information stored in one page at a time. This data is again stored and processed electronically by the digital computer.

Here, it is obvious that the reference wave should use the same one used for storing. When the reference wave is incident on the optical refraction recording medium, its accuracy depends on the thickness of the optical refraction recording medium. The thicker the optical refraction recording medium, the more accurately the reference beam should be irradiated. For example, in the case where the crystal is 10 mm thick, when the incident angle deviates by about 0.001 degrees, the reproduction image is completely lost.

As described above, the holographic multiplexing technique for storing a large amount of information can be implemented by varying the angle of incidence of the reference beam (or reference wave), which is an angular multiplexing that changes the angle, wavelength, and phase of the reference beam. Wavelength multiplexing, phase code multiplexing techniques, and spatial multiplexing techniques of spatial variation are known.

In general, in general holographic storage systems, holographic multiplexing techniques such as angular multiplexing, wavelength multiplexing, phase code multiplexing, spatial multiplexing, and the like, are generally applied in a separate and independent form.

Representative prior application examples related to the conventional hologram-based stereoscopic image display device based on such hologram technology include US Patent Application No. 03802769, Method apparatus for united stereo viewing, US Patent Application No. 04116526, Double modulation holographic recording technique, US Patent application No. 05644414, Stereoscopic display method of hologram and its forming method and its stereoscopic display apparatus, US Patent Application No. 05570208, Stereoscopic display method of hologram and its forming method and stereoscopic display apparatus, US Patent Application No. 05561537, Stereoscopic display method and Examples include an apparatus, US Patent Application No. 05548418, Holographic structured light generator, and the like.

The study of three-dimensional images begins with perspective paintings based on perspective in ancient Greek mural paintings from about 100 BC, and then by around 1,600 AD, Della Porta of Italy sees the picture with both eyes and feels the image floating. Since the first introduction of three-dimensional display postcards by parallax, it has been reproduced and reproduced by Charles Wheatstone in England, David Brewster in Scotland and Whendell Holmse in the United States. Early research to improve began in earnest, and in 1903, the FE Ives used a parallax barrier to create autostereoscopic stereograms and a US car in 1918. CW Kanolt is a parallax that ensures continuous three-dimensional images by securing defects with fixed viewpoints. A panorama grams (parallax panoramagram) announced respectively.

Stereoscopic imaging technology using binocular disparity among three technologies for displaying three-dimensional stereoscopic images shows stereoscopic images of two two-dimensional images with binocular disparity separately from the left eye and the right eye, thereby creating a space with a misalignment before and after the display plane. It can be reproduced. Since the invention of photography, it is easy to make stereoscopic pairs taken from two different angles by a camera, and a method of stereoscopic viewing with a stereoscopic viewer has been widely spread around Europe. It is the same as the principle of the stereoscope at the end of the 19th century in the sense that it uses the stereoscopic effect of polarized glasses type and stereoscopic high vision which is popular at exhibition fairs and theme parks. In addition, the use of parallax barriers and lenticular screens, which are being researched on the principle of stereoscopic television without glasses, is also derived from the stereoscopic photograph of the early 20th century. In addition, it is a display technology of a three-dimensional stereoscopic image that is put to practical use.

Representative prior applications related to the multi-view stereoscopic image display apparatus according to the prior art include US Patent Application No. 3818125 "Stereo television microscope", US Patent Application No. 5341434 "Method and apparatus for generating high resolution 3D images in a head tracked" stereo display system ", US Patent Application No. 4957351" Stereo image display device ", US Patent Application No. 5523886" Stereoscopic / monoscopic video display system ", US Patent Application No. 4654699" Three dimensional video image display system ", US patent Application 4691358 "Stereo image display device", US Patent Application No. 4247177 "3D Multichrome filters for spectacle frames", US Patent Application No. 4134644 "3D Color pictures with multichrome filters", US Patent Application No. 3959580 "Directly viewable stereoscopic projection system ", US Patent Application No. 5050961" Polarize d mask stereoscopic display including tiling masks with complementary transparent regions ", US Patent Application No. 4933755" Head mounted stereoscopic television viewer ", Republic of Korea Patent Publication No. 1997-058053," stereoscopic stereoscopic image display ", Republic of Korea Patent Application Examples such as 1987-012186, "stereoscopic image reproducing apparatus", Korean Patent Application No. 1987-010781 "display apparatus for stereoscopic image" Korean Patent Application No. 1994-014613 "stereoscopic image conversion apparatus", and the like.

However, the stereoscopic image display apparatus according to the prior art is not only difficult to secure a storage space for recording a large amount of stereo image data consisting of a left eye image and a right eye image, but also needs a storage medium capable of quickly accessing the recorded data. In order to view a 3D stereoscopic image, there are problems such as wearing special equipment such as a head mount or a shutter glass or glasses.

In addition, many methods have recently been proposed for the development of a 3D display system capable of observing a multiview image without special glasses. Among them, the lenticular-based method is attracting much attention and is being applied to commercialization of 3D TV system. The main disadvantage of this method is the separation and synthesis of multi-eye images captured from different fields of view into multiplexed stripe images (MSI) in real time. The analog system uses a method of mechanically combining NTSC signals to create multiplexed stripe pattern images (MSI) of left and right eyes, but this is limited in terms of system scalability. Digital-based systems have the advantage of scalability as multi- dimensional images as the number of camera channels, while the disadvantages of putting a lot of strain on the computer to synthesize multiplexed strip patterns in real time. That is, the increase of cyan is necessary to increase the high resolution and the wide viewing area, but in this case, it is difficult to process in real time, which is not suitable to implement the required system.

Accordingly, the present invention proposes an optical approach for synthesizing a multiplexed strip pattern image (MSI) in real time. Real time high-speed random access, eliminating the limitations and burdens of the computer in constructing the multiplexed strip image pattern (MSI) according to the multi-eye configuration, and securing a large amount of recording space by angular and spatial multiplexing Its purpose is to implement volume hologram technology that enables ultra-fast playback in real time.

Another object of the present invention is to provide a three-dimensional stereoscopic image without glasses by displaying on a three-dimensional image monitor in a multi-eye monitor.

To this end, a multi-eye image is continuously displayed on a spatial light modulator (SLM) on an object wave composed of plane waves, and the object wave is incident on an optical refraction medium. At this time, the object wave satisfying the Bragg matching condition is diffracted from the optical refraction recording medium to the designated position of the display plane, and received by the image sensor unit and displayed on the stereoscopic image monitor to provide a multi-dimensional three-dimensional display system using a volume hologram memory. The purpose is.

Another object of the present invention is to discretely rotate a photorefractive recording medium in accordance with a predetermined fine angle in a spatial area in order to increase the recording density of the photorefractive recording medium when constructing a high resolution multiplexed strip pattern image (MSI). By performing angular multiplexing and spatial multiplexing simultaneously to realize complex multiplexing combining angular multiplexing and spatial multiplexing, a high-density multiplexed strip pattern image (MSI) is constructed, so that it is faster and more reproducible. An object of the present invention is to provide a multi-eye stereoscopic video reproducing apparatus using a volume holographic memory capable of high speed reproduction.

1 is a block diagram showing a preferred embodiment of a multi-dimensional three-dimensional display device using a volume holographic optical device according to the present invention,

2 is a view for showing the geometry of a simple sinusoidal hologram,

3 is a spatial multiplexed hologram storage system diagram;

4 is a recording and reproducing diagram of a stereoscopic video pair;

5 is a recording and reproducing diagram of a four-eye stereoscopic image;

6 is a detailed principle diagram of a super multiview image display using a lattice structure and a volume hologram for reproducing a multi-view stereoscopic image;

7 is a lattice block diagram for multi-view stereo reproduction using spatial multiplexing,

8 is a block diagram showing a binocular video recording and reproducing system using volume holograms.

<Explanation of symbols for the main parts of the drawings>

10 laser 20 beam splitter

21: first aperture 22: second aperture

23 phase shifter 24 first spatial light modulator

25: second spatial light modulator 31: the first reflecting mirror

32: second reflector 33: third reflector

34: fourth reflector 41: first condenser lens

42: second condensing lens 43, 44: third condensing lens group

45: fourth condenser lens 50: photorefractive recording medium

60: third reflector rotating body 70: image sensor

60: monitor 90: stereoscopic video monitor

100: video recording / playback control unit

In the present invention, a diffraction grating that interferes with a reference wave and an object wave composed of a plane wave in the form of a strip is recorded in the optical refraction medium. At this time, the strip window width of the spatial light modulator through which the reference wave passes is adjusted to be equal to the angular pitch of the lenticular screen positioned at the display position and the strip pattern per pitch. The strip window width of the spatial light modulator through which the object wave passes is configured equal to the window width of the reference wave side, and is opened in synchronization with the object wave. The object waves are each multiplexed by the number of polynomials, the number of strips within a pitch of the lenticular screen. In the binocular case, the strip pattern of the spatial light modulator window through which the object wave passes is multiplexed at two angles, is incident on the optical refraction medium, and interferes with the strip window of the reference wave. In the case of polynomials, the number of polynomials is multiplied, and the interference is recorded with all strip patterns of the reference wave in turn.

In this way, the volume hologram with the interference pattern recorded acts as a passive element for stereo 3D image observation, and automatically creates a strip image when the multi-eye stereo image is input, and diffracts it to the designated position on the lenticular screen. . If a multi-eye image is updated in a spatial light modulator continuously in a time-division manner for one period and the angle of the object wave is changed in synchronization with it, a multi-eye 3D display system can be constructed. The theoretical analysis of the above-mentioned multi-eye stereoscopic image display system is shown, and the device for recording and reproducing the interference pattern of two plane waves in the volume hologram for the 2-view stereoscopic image display is shown.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of a multi-eye display device using a volume holographic memory according to the present invention will be described.

1 is a block diagram showing a preferred embodiment of a multi-eye display using a volume holographic memory according to the present invention.

As shown in FIG. 1, a multi-lens display device using a volume holographic memory according to the present invention is shown in FIG.

A laser (10) for generating laser beams of vertical deflection waves for generating plane waves;

A beam splitter 20 which optically separates the laser beam as it is incident to produce a reference beam and an object beam having the same wavelength as each laser beam;

The strip pattern light spatially multiplexed on the optical path through which the reference beam passes, and irradiated by the reference beam in the form of an input pattern having a light intensity modulation type corresponding to the multiplexed strip pattern image (MSI). A first spatial light modulator (SLM1) 24 for generating a modulated image;

The object beams are located on the optical path passing through them and are mixed with each other as they are irradiated by the beams in a state of forming a grid-shaped pattern corresponding to a polycular image for display in the form of a parallax barrier. A second spatial light modulator (SLM2) 25 configured to perform spatial multiplexing;

A first reflector (31) positioned between the beam splitter (20) and the first condenser lens (41) to change a traveling direction so that the beam is directed toward the beam splitter (20);

Second reflecting mirrors 32 and M1 positioned between the second condenser lens 42 and the optical refraction recording medium 50 to change the traveling direction so that the reference beam is directed toward the optical refraction recording medium 50; ;

The second spatial light modulator (SLM2) and the third condensing lens group 43 and 44 are rotatable, and the reference beams are respectively recorded according to the angle of incidence on the optical refraction recording medium 50. A third reflector 33 which is rotatable to generate and multiplex a grid pattern of each multiplexing and second spatial light modulator SLM2;

A third reflector rotating body (60) for providing a rotational force for rotating the third reflecting mirror (33) to change the reflecting angle of the third reflecting mirror (33) in response to the polycular image;

Electro-optical storage of holographic data in the form of an interference grating pattern formed by interfering with the object beam by the multi-eye light modulation image incident at different incidence angles is performed by optical refraction effect, and a reference beam satisfying Bragg matching conditions is incident An optical refraction recording medium 50 for spatially separating and reproducing the polycular image from the holographic data;

A phase shifter (23) for converting the vertical deflection wave from the beam splitter (20) and the laser beam (10) into a horizontal deflection wave to enable storage in the optical refraction recording medium;

A third condensing lens positioned between the third reflecting mirror 33 and the optical refractive recording medium 50 and condensing the object beam incident from the third reflecting mirror 33 to be incident to the optical refractive recording medium 50 Groups 43 and 44;

A first condensing lens (41) positioned between the laser (10) and the first reflecting mirror (31) and condensing a laser beam with a vertical plane wave;

A second condensing lens positioned between the first aperture and the second reflecting mirror and condensing the reference beam incident from the first spatial light modulator to be incident on the optical refraction recording medium;

A fourth condenser lens 45 positioned between the fourth reflecting mirrors and condensing the multi-lens image to be input to the image sensor unit when the multi-eye image is stored and reproduced;

A first aperture (21) positioned between the beam splitter (20) and the second reflector (32) to transmit or block the reference beam;

A second aperture 22 positioned between the phase shifter 23 and the second spatial light modulator 25 to transmit or block the object beam;

A fourth reflector 34 positioned between the optical refraction recording medium 50 and the fourth condenser lens 45 to reflect the incident light to the image sensor unit CCD 70 when the multi-eye image is stored and reproduced. );

The rotation control signal applied to the third reflector rotating body 60 by varying the multi-spatial image spatially multiplexed by the second spatial light modulator SLM2 in the lattice pattern method is different from each other. The multiplexing angle in the optical refraction recording medium 50 is controlled by controlling the rotation angle of the optical refraction recording medium 50 by controlling the respective rotation angles so that the optical refraction recording medium is multiplexed and spatially multiplexed to the optical refraction recording medium 50. An image recording / reproducing control unit 100 for controlling the optical path such that the multi-view image having the same match is reproduced;

In the image sensor unit 80 which performs photoelectric conversion, respectively, in order to read the polycular image reproduced from the optical refraction recording medium 50 in the form of an electrical signal under the control of the image recording / reproducing controller 100. The reproduced image is input to a computer and synthesized to view a multi-eye image without glasses using a three-dimensional image monitor 90 having a grid pattern.

Here, the spatial light modulation unit groups 24 and 25 use Liquid Crystal-Spatial Light Modulator (LC-SLM), and the medium rotating body 60 uses a step motor. Examples of the material of the volume holographic optical device 50 include nonlinear crystals such as LiNbO ₃ , BSO, and BaTiO ₃ .

Hereinafter, with reference to the accompanying drawings, the operation of the preferred embodiment of the device according to the present invention configured as described above and the operation principle and effects will be described in detail as follows.

The present invention forms a multiplexed stereoscopic image pair, a multiplexed strip pattern image (MSI) of an object beam and a reference beam (i.e., reference wave), stores them in the optical refractive recording medium 50, and satisfies Bragg matching conditions. The reference beam is incident on the optical refraction recording medium 50 so that the 3D stereoscopic image can be observed by reproducing the polycular image. In this case, the multiplexing method is used alone or in the spatial multiplexing alone. The recording density of the optical refraction recording medium 50 is increased by using a multiplexing method using a combination of the multiplexing method and the spatial multiplexing method.

As described above, the present invention can increase storage capacity and provide fast access to each multiplexing method and spatial multiplexing method. And spatial multiplexing will be described in detail with reference to FIG. 2.

FIG. 2 is a diagram illustrating the geometry of a simple sinusoidal hologram. The first diagram of FIG. 2 is a diagram showing a structure of forming a sinusoidal grating of a volume hologram by two plane waves of an object beam and a reference beam, and the second of FIG. The figure shows a wave vector spatial diagram formed by holographic interaction.

First, angular multiplexing means that the volume hologram recorded as an object beam (i.e., an object wave) and a reference beam (i.e., reference wave) having a specific angle is an angle between the reference beam at the time of recording and the reference beam at the time of restoration. It is based on Bragg's matching condition that it is restored depending strongly on.

Each selectivity can be best described and quantified for the case of a simple sinusoidal grating recorded by two plane waves, as can be seen in the first diagram of FIG. 2.

Here, the incident angles of the reference beam and the object beam measured in the optical refractive recording medium 50 (for convenience of description, the thickness of the optical refractive recording medium 50 will be denoted by L _z ) are respectively θ _R and θ _O. When expressed as, the wave vector k _O of the object beam and the wave vector k _R of the reference beam are each expressed as in Equation (1).

Where n is the refractive index of the medium and λ is the wavelength of light in the vacuum.

In this case, the grid vector K in the wave vector spatial figure is called a set of all possible wave vectors k corresponding to the plane waves traveling in the medium. Considering only the case of an isotropic sphere, the Bragg matching condition to be satisfied for the input reference wave to cause diffraction is given by Equation (2).

Where k _O 'is the wave vector of the scattered object beam and k _R ' is the wave vector of the incident reference beam, and Represents the degree of predetermined phase mismatch that may occur due to the thickness of the medium. Typically for weak scattering (ie diffraction efficiency In << 1), the diffraction efficiency is expressed by Equation 3 below.

While reading the information, the direction of the reference beam must be within the range defined by Equation 4 to cause diffraction to be fully observed.

Usually, the phase mismatch with respect to the direction of the angle for synchronizing with the angle when recording the angle of the incident reference beam has anisotropy. Because, as in the second diagram of FIG. 2, the wave vector of the reference beam can be rotated in a direction perpendicular to the plane defined by k _R and k _O that satisfy the Bragg matching condition with zero phase mismatch, and rotate in the plane. This is because the phase mismatch caused by this increase also increases. In this case, in contrast to the increase in the phase mismatch, the width of the angle satisfying the Bragg matching condition of zero phase mismatch can be found. That is, the angular selectivity in the plane is approximately given by the width of the angle between the points where zero is first generated in Equation (3).

Equation 5 is usually correct for small θ _O. Also, the angular selectivity is best when the angle θ _R + θ _O of the object beam and the reference beam is 90 _° , and the angular selectivity starts to fall symmetrically about this angle.

In order to store multiple holograms in the same volume, an image without cross talk may be obtained by multiplexing and restoring the same plane using reference beams spaced by an increment of an angle given by Equation 5.

The number of holograms that can be multiplexed within a given range from the angle θ ₁ to θ _m of the reference beam is approximately given by equation (6).

Therefore, by using angular multiplexing, M pieces of information can be stored as shown in Equation (6). At this time, it is obvious that each angle performs a 'address' function for accessing the recorded information.

Subsequently, the spatial multiplexing will be described. In general, the total number of holograms (M) and the hologram diffraction efficiency ( ) Is given by the equation (7).

In the common sense _max , τ _ω , τ _{ε correspond} to maximum efficiency, write and erase time constants. The result of equation (19) is given when all the recorded hologram data are designed to have the same diffraction efficiency. _{When max} = 1, τ _ω = τ _e and 10,000 holograms are stored, the resulting diffraction efficiency is about 10 ^-8, and when it is lowered below it, it is impossible to detect from the image sensor unit 70 due to noise or the like. . Therefore, it is possible to increase by spatially multiplexing such a number of volume holographic optics as a method for storing each hologram data. 3 shows a stacked form of such an array of volume holographic recording units. Here, the "coarse" address deflects the write and read beam to the appropriate layer (spatial multiplexing) and the "fine" address deflects to a specific hologram page within the volume holographic unit of the selected layer.

As described above, the present invention performs angular multiplexing by discretely rotating the optical refraction recording medium according to a predetermined fine angle in the spatial domain, and at the same time the spatial light modulator (SLM) of the object beam and the reference beam. By using the multiplexing method combined with the spatial multiplexing, ultra-high speed, high-resolution multiscopic stereoscopic images are stored in the optical refraction recording medium 50.

Hereinafter, a multi-eye image display for observing three-dimensional stereoscopic images with a stereoscopic image monitor such as a Ferrax barrier monitor without requiring special equipment such as a shutter glass or a head mount of FIG. It will be described in detail with reference to.

First, the recording and playback of a monocular stereoscopic pair, which is the basic method of multi-eyes, will be described in order to deepen the theoretical understanding.

According to the present invention, when the object wave and the reference wave passing through the spatial light modulator SLM on which two stereoscopic pair images are displayed satisfy the interference condition, three waves form a lattice pattern by interference.

The wave equations for the three waves as shown in FIG. 4 (a) can be expressed by Equation 8.

Where E ₁ and E ₃ are stereoscopic image pairs and E _R is the reference wave, A ₁ , A ₂ and A _R are the amplitudes, ω is the angular frequency, and k ₁ , k ₂ and k _R are the waves. It is a vector. Time-interfering E ₁ , E _R and E ₂ , E _R in 45 ° -cut photorefractive medium as shown in FIG. 4 (a), the intensity distribution in the medium is represented by Equation 9.

The change in intensity distribution due to the interference forms a lattice pattern caused by the change in the refractive index of the medium. As shown in FIG. 4, when the reference wave A _R = 1 that satisfies the Bragg matching condition is irradiated, the intensity distribution in the stereoscopic display plane is expressed by Equation 10.

In Equation 10, the second and third terms are diffracted in the direction in which the stereoscopic image pair is recorded, and are output to the display plane for 3D stereoscopic image observation.

The stereoscopic image pair reproduced above is incident on an image sensor unit such as a CCD to observe a stereoscopic image through a 3D display system, or may be directly observed by configuring a system such as a stereoscopic viewer.

Hereinafter, the present invention is deeply related to the recording and reproducing technology of a multi-eye stereoscopic pair, which will be described in detail in order to provide a depth of theoretical understanding thereof.

When n stereoscopic pair images and one reference wave satisfy an interference condition, wave equations for them may be expressed by Equation 11.

Here, E ₁ , E ₂ , ..., E _n are stereoscopic video pairs and E _R is a reference wave. A ₁ , A ₂ , ..., A _n , A _R are the amplitudes, ω is the angular frequency, and k ₁ , k ₂ , ..., k _n , k _R are wave vectors.

FIG. 5 is a recording and reproducing diagram of a four-eye stereo image. In FIG. 5 (a), intensity distribution in an optical refraction recording medium when E ₁ , E ₂ , E ₃ , E _4, and E _R are time-divisionally interfered. Is the same as (12).

As shown in FIG. 5B, when the reference wave A _R = 1 that satisfies the Bragg matching condition is irradiated, the intensity distribution in the stereoscopic display plane is expressed by Equation 13.

Only the second to fifth terms of Equation 13 are diffracted in the output plane. Considering the case where n object waves and one reference wave interfere in time division, the intensity distribution of the interference wave formed in the optical refraction medium is expressed by Equation 14 below.

When the reference wave A _R = 1 that satisfies the Bragg matching condition is irradiated, the intensity distribution in the stereoscopic display plane is expressed by Equation 15 below.

The term in the second line in Equation 15 represents the diffraction term of the recorded multiple stereo pairs.

Hereinafter, since the system is a multi-eye display method using the angular multiplexing / spatial multiplexing method, the following description will be given.

The multi-eye image is projected onto the display plane to record the three-dimensional image, and the lattice pattern is recorded on the volume hologram, and then the multi-eye image is updated to the spatial light modulator (SLM) in a time-division manner. Configure a system that can be displayed. One object wave image is composed of n strip patterns, and in the case of m rest system, the object wave is multiplexed m times and interferes with the reference wave. The entire window of the first spatial light modulator SLM1 24 through which the reference wave passes is composed of a strip window having a resolution of n × m. It interferes with the object wave number m in a spatial multiplexing scheme in which all window strips corresponding to m rest of each pitch are opened.

During reproduction, if a lattice pattern is formed in this manner and then an object wave composed of multi-view images satisfies Bragg conditions and is incident on the volume hologram time-divisionally, the incident image is scattered by the recorded diffraction grating to change the direction of the lattice. Is diffracted accordingly. At this time, since the multi-view images incident in time division are multiplexed with each other, they are diffracted in a predetermined direction of each pitch. Therefore, it is apparent that a multiview stereoscopic image can be observed from the projected polycular stereoscopic image which is diffracted to the display plane after one period in which the entire multiview image is updated.

The wave equation for the object wave and the reference wave consisting of the plane wave is shown in Equation 16 below.

Here, E _{O (pq)} and E _{R (pq)} are an object wave and a reference wave (| E _{O (pq)} | = | E _{R (pq)} | = 1) respectively configured in the form of a plane wave stripe. Ω is the angular frequency, and k _{O (pq)} , k _{R (pq)} is the _wavevector , n is the number of pitches of the lenticular screen, and m is the number of polyculars.

6 is a diagram illustrating a lattice configuration and a multiview stereoscopic image display for a multi-eye stereoscopic display. As shown in FIG. 4 (a), when all reference waves composed of plane waves in time division and the stripe image of the object wave are interfered, the intensity distribution in the optical refraction recording medium is expressed by Equation 17.

It can be seen that in Equation 17 is the same as in Equation 14 except that the point consisting of the interference pattern of the plane wave and the multiple object waves are each multiplexed.

As shown in FIG. 6 (b), when the polycular image wave satisfying the Bragg matching condition is irradiated, the intensity distribution in the stereoscopic display plane is expressed by Equation 18.

The multiview stereoscopic image of the object wave incident through the spatial light modulator SLM is properly diffracted onto the display plane as shown in the second line of Equation 18, so that the multiview stereoscopic image can be observed by the lenticular screen.

When multiplying an object wave composed of plane waves by the number of multiviews and angularly multiplying the reference wave by the number of strip patterns x the number of polynomials, the resolution of the spatial light modulator (SLM) on the reference wave is a problem. That is, if one object wave image is composed of m strips with n strip patterns, the SLM window bandwidth of the reference wave should be n X m. In addition, if the spatial wave modulator (SLM) strip window spacing between the object wave and the reference wave is equal to each other, the vertical resolution of the stereo image is reduced to 1/2.

7 is a block diagram of a grid configuration system for two-view stereoscopic image reproduction using spatial multiplexing. In the system, the number of stripe windows of each of the spatial light modulator groups SLM1, SLM2, and SLM3 is n, and then the second spatial light is sequentially opened while the windows of the first spatial light modulator SLM1 are sequentially opened on a stripe pattern strip. By alternately opening the windows of the modulator SLM2 and the third spatial light modulator SLM3, the reference wave window plane wave of the first spatial light modulator SLM1, the second spatial light modulator SLM2, and the third spatial light The plane wave of the object wave window of the modulator SLM3 is time-divisionally recorded. Alternatively, all odd windows of the first spatial light modulator SLM1 and the second spatial light modulator SLM2 are opened and a pattern is recorded, and then the first spatial light modulator SLM1 and the second spatial light modulator SLM2 are recorded. Open the even window of) to record the pattern. In this case, since the stripe images of the second spatial light modulator SLM2 and the third spatial light modulator SLM3 are each used 1/2, the resolution of the reproduced multi-eye image is reduced to 1/2. In the actual embodiment, as shown in FIG. 7, the spatial light modulator (not shown) in the first half of the mirror without using two spatial light modulators of the second spatial light modulator SLM2 and the third spatial light modulator SLM3 on the object wave side. One SLM) was placed and used. In this case, the same effect can be obtained by updating the spatial image modulator (SLM) stereo image in a time-division manner and angular multiplexing by adjusting the third reflector. In the case of polynomial expression, the same effect can be obtained by multiplying each multiple as much as the multiple eye.

Hereinafter, the operation of the preferred embodiment of the device of the present invention will be described in detail with reference to FIGS.

In describing the operation of another embodiment of the present invention, unnecessary overlap with the description of the preferred embodiment of the present invention will be omitted within the allowable range of those skilled in the art.

1 and 8, after recording the interference pattern of the reference wave and the object wave consisting of a vertical strip shape, it is a system diagram that can update the multiview image in time division and observe the multiview image. The system is designed to record and reproduce multi-view strip patterns using two spatial light modulators (SLMs 24 and 25). The system is largely composed of a reference wave passing unit, an object wave passing unit, and a stereoscopic display unit. In addition, by using a computer interface that is a video recording / playback control unit 100, all the processing is automated to form a single integrated system.

First, a process of storing a multiplexed strip pattern image in a photorefractive recording medium will be described in detail with reference to FIGS. 1 and 8 as follows.

As shown in FIG. 1, the beam emitted by the laser makes the beam a plane wave using a laser spatial filter. The laser beam is incident on the beam splitter after passing through a first reflector for condensing the light through the first reflector to the beam splitter by the first condenser and changing the path of the laser beam.

The laser beam is then made into a beam with two different characteristics, one being a reference beam for recording a strip pattern by spatial multiplexing on a photorefractive recording medium and the other forming a multiplexed strip pattern (MSI). An object beam that provides a polycular image to be recorded on the refractive recording medium.

First, the path through which the object beam passes will be described. The second spatial light outputs an object beam composed of plane waves having different angles according to each of the polycular images and stores the image in the optical refraction recording medium through the third condensing lens group. The second reflector and the second spatial light modulator digitally control the recording and reproduction of the image by covering or passing the multi-view multiplexed strip image (MSI) pattern through the modulator, and then beaming the object beam through the third reflector. The third reflector and the third reflector to change the path of propagation, but to give the rotational force to a rotating body such as a step motor so that the angle of incidence to the optical refraction recording medium can be stored in each multiplexing manner that can be stored for each angle. Through the whole, a third condensing lens group for condensing the beam by making a plane wave in accordance with the size of the optical refraction recording medium is collected. It is finally stored in a photorefractive recording medium.

Next, the path through the reference beam will be described. Like the reference beam, the first spatial light modulator (SLM1; 24) through the first aperture allows digital control from the computer interface card to obstruct or pass the reference beam. A multiplexed strip pattern image (MSI) is given to the multiplexer to be spatially multiplexed to be stored in the optical refraction recording medium.

Referring to FIG. 8, in the case of two-eyes, if the left and right eye images are stored in the same manner in the same way, the strip pattern is stored in the optical storage recording material. When the strip pattern and the strip pattern corresponding to the right eye are each multiplexed and stored, the third reflector rotating body can be rotated to reproduce the left and right in succession to form a complete 3D display device.

In the above, the procedure for storing the multiplexed strip image pattern (MSI) in the optical refraction recording medium using each multiplexing and spatial multiplexing and the description of each element have been described in detail.

Hereinafter, a method of storing the strip pattern formation process and the process of constructing a multi-eye stereoscopic image in the optical refraction recording medium through each multiplexing and spatial multiplexing, and how the stored images are displayed and the 3D stereoscopic image can be viewed. 1 and 8 will be described in more detail as follows.

For example, when one object wave image has n strips and is composed of m rests, a method of recording an image on a light refractive medium is as follows. At this time, both the object wave and the reference wave for recording the interference pattern are composed of plane waves. The third reflector rotating body 60 is rotated to a position where the plane wave corresponding to one of the polycular (m) images is to be recorded. The image of each viewpoint is composed of n strip patterns. The recording of the strip pattern for the first time point of the object wave starts with the first strip pattern, skips the polycular (m) field, and opens all strip patterns. The reference wave opens all the first windows of each pitch. The apertures IRIS1, 2; 21, 22 are opened to allow the pattern to be recorded on the photorefractive medium 50.

Next, the third reflector M3 33 is rotated to the position where the second image of m rest is to be recorded. The recording of the strip pattern of the second image is the same as the first image, starting with the second strip pattern of the object wave, skipping the polycular (m) field, and opening all strip patterns. The reference wave will record with all the second strip windows open at each pitch. In this manner, the third reflector (M3) 33 is multiplexed according to the multi-view m, and the interference pattern is recorded m times by opening the strip window of the reference wave.

In the embodiment of the present invention, an embodiment of two eyes was performed and one first spatial light modulator (SLM1) 24 was used on the reference wave side. Accordingly, the angle of the third reflector (M1) 33 is left while opening the strip window pattern of the object wave-side second spatial light modulator (SLM2) 25 in odd and even order for recording the left and right eye images and the reference wave. Odd window opening in the right direction and even window opening in the right direction were recorded.

When the interference pattern is recorded in the optical refraction medium 50 in this manner, the first aperture IRIS1 21 is blocked and the left eye image and the right eye image are time-divisionally updated in the second spatial light modulator SLM2. In addition, since the third reflector 33 is rotated, the multi-view image may be observed by an image sensor unit such as a CCD on the display plane.

By viewing such a multi-eye image on a stereoscopic monitor, it is possible to see a high-speed real-time three-dimensional stereoscopic image, and by solving the time problem, it is possible to construct a three-dimensional stereoscopic image communication system through the Internet.

Therefore, such a technique is considered to be cited in the technical spirit of the present invention, it is obvious that the claim belongs to the claims of the present invention.

Representative spatial light modulators (SLMs) used as spatial light modulators (SLMs) use liquid crystal-spatial light modulators (LC-SLMs). It is outputted in phase. In this example, the BE13X010 is used to convert a video signal, which is an analog signal output to a computer, into a digital signal. An example of the volume holographic optical device 50 is 45 ° cut LiNbO _{3 to} which iron is added. And two apertures (IRIS1 and IRIS2; 21 and 22), periscopic mirrors (Periscopes) for adjusting the beam height, and a driving motor such as a step motor for multiplexing and storing the optical refraction medium 50. A third reflector rotating body 60 and the like were used.

In order to control various devices with a computer, an interface card was attached to an expansion slot (ISA) of a PC to control an external device through a program. The external device can be classified into two types, as the third reflector rotating body 60 and the iris IRIS 21 and 22 control unit. The external device controls the reference beam incident on the optical refraction medium to implement angular multiplexing. As the reflector rotating body, a stepping motor having a step angle of 1.8 ° was used. A 1.8 ° stepping motor was mounted on the gear box of the third reflector rotor so that the mirror could be controlled to 0.01 °. The drive outputs data to the expansion slot in the program so that the signal is amplified by the power capable of driving the third reflector rotating body in the power amplifier through the interface IC and then input to the control terminal of the third reflecting body rotating body. The reflector rotating body was driven. In addition, the digital aperture system is implemented by using the apertures IRIS 21 and 22 to control the exposure time of the light. The control signal was converted into an input signal. The first aperture IRIS1 21 is used to control the beam of the laser output stage and the second aperture IRIS2 22 is used to control the object wave.

In the above-described preferred embodiment of the present invention and another embodiment of the present invention, in order to increase the recording density of the optical refraction recording medium 50, spatial multiplexing is performed to spatially separate an image, and the third reflector rotating body is finely adjusted. Although the multiplexing method combines two multiplexing methods by performing angular multiplexing by rotating at an angle, two spatial light modulators (SLM; 24, 25) complicates the configuration and control of the system in that it has the advantage of increasing the recording density of the optical refraction recording medium 50, and also increases the manufacturing cost of the system. According to the design policy, instead of using two spatial light modulators (SLM) 24,25, one spatial light modulator is used and only a third reflector is used. It is apparent that only the rotator 60 may be used to perform only each multiplexing. Therefore, such a technique is also considered to be cited in the technical spirit of the present invention, it is obvious that it belongs to the claims of the present invention.

On the other hand, in the present invention, by storing the image of the strip pattern form through the first spatial light modulator and the second spatial light modulator more quickly and efficiently to increase the recording density of the optical refraction recording medium, more multi-eye stereoscopic image is added It is a system that can record and play back at high speed. Therefore, a device for forming a multiplexed strip pattern image (MSI) and storing such an object wave and a reference wave in an optical refraction recording medium and then reproducing multi-eye images at high speed. Therefore, such a technique is also regarded as reciting the technical idea of the present invention, and it is obvious that it belongs to the claims of the present invention.

Terminologies used herein are terms defined in consideration of functions in the present invention, which may vary according to the intention or customs of those skilled in the art, and the definitions should be based on the contents throughout the present application. something to do.

In addition, since the present invention has been described through the preferred embodiment of the present invention, in view of the technical difficulty aspects of the present invention, a person having ordinary skill in the art can easily be different from another embodiment of the present invention. As modifications may be made, it is obvious that both the embodiments and modifications cited in the above description belong to the claims of the present invention.

The present invention is a multi-view stereoscopic display system in which an interference pattern of an object wave and a reference wave composed of a plane wave of a strip pattern is stored in a volume hologram, and time-divisionally updated a multiview stereo image to observe a diffraction pattern. Multi-volume and resolution can be obtained as much as the volume holographic optical device is allowed to be multiplexed, and since the optical refraction medium serves as a passive device after recording the diffraction pattern, it is possible to display a multi-eye image in real time. Therefore, it is possible to achieve high speed and real time, so that in the future, advances in wired and wireless communication networks such as local area network (LAN), wide area network (WAN), intranet, extranet, internet, etc. In addition, there is an advantage to configure a three-dimensional stereoscopic video communication system that supports MOD (Multimedia On Demand) on such a communication network

In addition, it is expected to be applied to a high-resolution autostereoscopic multi-view stereoscopic image display system that does not require equipment such as shutter glasses or a head mounted display (HMD).

Claims (10)

A laser for generating laser beams of vertical deflection waves that produce plane waves; A beam splitter which optically separates the laser beam as it is incident to produce a reference beam and an object beam having the same wavelength as each laser beam; The strip pattern light spatially multiplexed on the optical path through which the reference beam passes, and irradiated by the reference beam in the form of an input pattern having a light intensity modulation type corresponding to the multiplexed strip pattern image (MSI). A second spatial light modulator for generating a modulated image; The object beams are located on the optical path passing through them and are mixed with each other as they are irradiated by the beams in a state of forming a grid-shaped pattern corresponding to a polycular image for display in the form of a parallax barrier. A second spatial light modulator for spatial multiplexing by making a second shape; A grid pattern is provided between the second spatial light modulator and the third condensing lens group to be rotatable, and each of the multiplexing and second spatial light modulators in which an object beam is recorded according to an angle incident on the optical refraction recording medium is generated. A third reflector configured to be rotatable to store and reproduce the multi-view image by performing spatial multiplexing; A third reflector rotating body which provides a rotational force for rotating the third reflecting mirror to change the reflecting angle of the third reflecting mirror corresponding to the polycular image; Electro-optical storage of holographic data in the form of an interference grating pattern formed by the multi-eye light modulated images incident at different incidence angles interfering with the reference beam is electro-optically stored by a photorefractive effect, and a reference beam satisfying Bragg matching conditions is incident A volume holographic optical element that spatially separates and reproduces the polycular image from the holographic data; And By varying the rotation control signal for applying the multi-lens image spatially multiplexed by the second spatial light modulator to the third reflector rotating body in the lattice pattern method to have different rotation angles, By controlling the angle of rotation of the optical refraction recording medium by multiplexing and spatially multiplexing the optical refraction recording medium, the optical refraction recording medium is controlled so that the optical path is reproduced so that the multi-view image having the same multiplexing angle is reproduced. Ultra multi-eye stereoscopic three-dimensional image recording / reproducing apparatus using a volume holographic optical element, characterized in that further comprising an image recording / playback control unit. The method of claim 1, A first reflector positioned between the beam splitter and the first condenser lens to change a traveling direction so that the beam is directed toward the beam splitter; A second reflector positioned between the second condenser lens and the optical refraction recording medium to change a traveling direction so that the reference beam is directed toward the optical refraction recording medium (50); And And a fourth reflector positioned between the optical refraction recording medium and the fourth condenser lens to reflect the input image to the image sensor unit when the recorded image is reproduced. Stable stereoscopic video recording / playback device. The method of claim 2, A first condensing lens positioned between the laser and the first reflecting mirror and focusing the laser beam uniformly with a vertical plane wave; A second condensing lens positioned between the first aperture and the second reflecting mirror and condensing the reference beam incident from the first spatial light modulator to be incident on the optical refraction recording medium; A third condensing lens group positioned between the third reflecting mirror and the optical refraction recording medium to condense an object beam incident from the third reflecting mirror to be incident on the optical refraction recording medium; And And a fourth condenser lens positioned between the fourth reflectors to condense the multi-lens image to be input to the image sensor unit when the multi-eye image is stored and reproduced. Video recording / playback device. The method of claim 1 And a phase shifter for converting the vertical deflection wave from the beam splitter and the laser into a horizontal deflection wave so as to enable storage in the optical refraction recording medium. The method of claim 1, A first aperture positioned between the beam splitter and the second reflector to transmit or block the reference beam; And And a second aperture positioned between the phase shifter and the second spatial light modulator to transmit or block the object beam. The method of claim 1, By varying the rotation control signal for applying the multi-lens image spatially multiplexed by the second spatial light modulator to the third reflector rotating body in the lattice pattern method to have different rotation angles, By controlling the rotation angle of the optical refraction recording medium by multiplexing and spatially multiplexing the optical refraction recording medium, the optical refraction recording medium is controlled so that the optical path is reproduced so that the multiplexing image having the same multiplexing angle is reproduced. Multi-view stereoscopic video recording / playback apparatus using a volume holographic memory, characterized in that it further comprises a video recording / playback control unit. The method of claim 1, And further comprising an image sensor unit for performing photoelectric conversion to read the polycular image reproduced from the optical refraction recording medium in the form of an electrical signal under the control of the image recording / reproducing controller. Multi-eye Stereoscopic Video Record / Playback Device Using Memory The method of claim 1, The spatial light modulator uses a liquid crystal-spatial light modulator (LC-SLM), the multi-view stereoscopic image recording / playback apparatus using a volume holographic memory. The method of claim 1, The third reflector rotating body is a multi-eye stereoscopic image recording / reproducing apparatus using a volume holographic memory, characterized in that each step motor. The method of claim 1, The material of the volume holographic optical device is any one of LiNbO ₃ , BSO, BaTiO ₃ , Polymer, characterized in that the multi-eye stereoscopic image recording / playback apparatus using a volume holographic memory.