Patent Application
20120019883
The present invention disclosed herein relates to a holographic display, and more particularly, to a spatial light modulation panel system which enables the formation of high-density pixels and has a fast response time, and to a holographic display which integrates and displays an image by sequentially moving a spatial light modulator or displays a high-resolution three-dimensional (3D) image in a scheme of overlapping a hologram fringe pattern.
A 3D holographic technology fundamentally prevents eye fatigue that is caused by a 3D scheme of allowing a 3D image to be viewed with binocular disparity, and is drawing much attention as a next generation 3D image technology that is ultimately required. In a holographic image, a user directly views the forming of an actual image with eyes unlike in the existing scheme that allows a user to feel dimensionality through an optical illusion, and thus, the user feels dimensionality as in the viewing of a real object. Therefore, even when a user views a holographic image for a long time, the user does not feel fatigue.
Dr. Gabor discovered the holography technology while researching a method that records the wave front of an electron beam and enhances a resolving power of an electron microscope, in 1949. Afterward, technology has been advanced highly, and thus, a photograph technology that records a hologram in a film and reproduces the recorded hologram by using a light has been advanced by the degree where a natural color image may be realized in high resolution. In technology that electronically displays a moving image, however, in order to obtain and process massive hologram data, high-density electronic devices are required to be developed, and a data processing speed and a data transmission speed are required to be advanced far higher than the current technology. That is, the technology that electronically displays a moving image is in an initial stage.
The Two-Dimensional (2D) photograph technology records only the intensity of a light and reproduces an image, but the holography is technology that records the intensity and phase of a light together and reproduces a Three-Dimensional (3D) image. The holography records an interference fringe between a reference wave and an object wave, reflected by an object, in a photosensitive film in a hologram type by using a coherent light source. That is, the existing 2D photograph technology directly records an image in a film, but the holography does not record an image but records an interference fringe in a photosensitive film. Herein, when irradiating a reference wave on a hologram photosensitive film, the phase of an object is reproduced in the original location as-is according to the light diffraction principle. Above all, a photosensitive film is required to have a high resolving power so as to see a high-resolution image within broad view. To date, many hologram photosensitive films for realizing high resolution have been developed.
However, technology of manufacturing an electronic device that electronically acquires and displays a hologram is largely insufficient to obtain a high-resolution image. That is, a capture device or a display having several to tens of billions (G) or more of pixels is required for displaying all the amount of hologram information. The amount of information included in a hologram is simply calculated by computing the number of interference fringes with the Bragg diffraction equation “2d·sinθ/λ”. Herein, d indicates a hologram size, λ indicates a wavelength of a light, and θ indicates an angle between a reference wave and an object wave when recording a hologram. For example, even when it is assumed that a 10 cm×10 cm hologram is recorded at an angle of 30 degrees by using the He—Ne laser (λ=0.6328 μm), the total amount of information is about 25 gigabyte (GB). Therefore, when a high-density hologram display device having a pixel size of 0.6 μm or less has been developed, a high-resolution 3D image can be displayed.
Recently, the digital holography technology has been advanced highly, and thus, technology of acquiring an image to generate a hologram is approaching a realizable level. Technology, which uses a camera for obtaining depth information or captures an image in an integral imaging method to generate a hologram, is being developed, and particularly, an operational algorithm that considerably reduces the amount of hologram information by decreasing vertical parallax has been developed. Therefore, there is very high possibility that the technology of acquiring an image to generate a hologram will be realized due to the current advance of a data processing speed and data transmission speed.
A method of displaying a hologram uses an Acousto-Optic Modulator (AOM) or a Spatial Light Modulator (SLM) such as a Liquid Crystal Display (LCD). The Massachusetts Institute of Technology (MIT) space imaging group and Korea Institute of Science and Technology (KIST) have manufactured the multi-channel AOM to display a 3D image. However, since AOMs fundamentally display a linear hologram, the AOMs have a limitation in that the AOMs show only horizontal parallax. Also, since AOMs have a mechanical scheme that uses a vertical mirror, a polygon mirror, etc., the AOMs have a relatively complicated structure. Chiba University in Japan, etc., is making an effort to realize a moving image of a natural color with an SLM such as an LCD. However, since LCD devices have limitations in that it is difficult to realize a fast response time and a high density, current technology cannot fundamentally realize a high-resolution 3D image.
The present invention provides a holographic display, which realizes a high-resolution three-dimensional (3D) image by using a spatial light modulator, manufactured with a dielectric thin film or a polymer thin film having a fast response time, in order to solve difficulties (which occur in the existing acousto-optic modulator or spatial light modulator such as an LCD) in realizing high-density pixels.
The present invention also provides a spatial light modulation panel system which displays a hologram while sequentially moving a spatial light modulator having a fast response time, thereby displaying a high-resolution 3D image.
In embodiments of the present invention, a holographic display includes; a spatial light modulator using a polymer thin film or a dielectric thin film that enable the formation of high-density pixels and has a fast response time; a fine displacement panel system sequentially moving the spatial light modulator in synchronization with a hologram fringe signal; and an optical system including a coherent light source, a spatial light modulation panel system, and an optical element.
The polymer thin film and the dielectric thin film have a very large electro-optic coefficient and have a fast response time when an electric field is applied, and thus have features suitable for being applied to the spatial light modulator.
The spatial light modulator having a fast response time is formed by stacking a vertical polarizer and a horizontal polarizer at respective both surfaces of a panel that is formed with the polymer thin film or the dielectric thin film.
The spatial light modulator controls the polarization of an incident light to modulate a light by using the electro-optic effect of the polymer thin film or dielectric thin film.
A method of forming the spatial light modulation layer includes: a process that deposits the polymer thin film or the dielectric thin film on a transparent substrate or a lower transparent electrode/the transparent substrate; a process that performs patterning for each pixel; an operation that forms a metal electrode; and an operation that forms a thin film transistor in each pixel.
The spatial light modulator having a fast response time changes a phase of a light to control the modulation of a light without using a polarizer.
The fine displacement panel system provides a device that displays a hologram fringe pattern while sequentially moving the spatial light modulator in synchronization with a hologram fringe signal.
In such scheme, when it is assumed that a 3D image before division is one frame 3D image, a sequentially-reproduced 3D image is integrated in one frame before division, thereby realizing a high-resolution 3D image.
In the above-described scheme, another scheme duplicates and records a hologram, which is displayed on an Electrically Addressed Spatial Light Modulator (EASLM) that sequentially moves and records a hologram as an electric field, in an Optically Addressed Spatial Light Modulator (OASLM) that records a hologram as a light to generate a high-density hologram, thereby realizing a 3D image.
The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings:
Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.
The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that those skilled in the art thoroughly understand this present invention. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Also, in the figures, the dimensions of layers and regions are exaggerated for clarity of illustration.
In the following description, the technical terms are used only for explaining a specific exemplary embodiment while not limiting the present invention. The terms of a singular form may include plural forms unless referred to the contrary. The meaning of ‘comprises’ and/or ‘comprising’ specifies a property, a region, a fixed number, a step, a process, an element and/or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and/or components.
Additionally, the embodiment in the detailed description will be described with sectional views as ideal exemplary views of the present invention. Accordingly, shapes of the exemplary views may be modified according to manufacturing techniques and/or allowable errors. Therefore, the embodiments of the present invention are not limited to the specific shape illustrated in the exemplary views, but may include other shapes that may be created according to manufacturing processes.
Referring to
The lighting part includes a laser or Light Emitting Diode (LED) light source 101 emitting a coherent light, an object lens 102 changing a light to a flat light, a spatial filter using a pin hole 103, and a collimating lens 104. Such elements may be appropriately disposed to be separated from each other according to the diameter of a desired flat beam.
The spatial light modulation panel system displaying the hologram fringe pattern is designed and manufactured to display the hologram fringe pattern while sequentially moving a spatial light modulator 105. A computer 108 such as a Personal Computer (PC) may control the spatial light modulator 105 that displays a hologram fringe pattern while sequentially moving.
By optimizing an optical system, the optical part 106 reproducing a 3D image is designed to a reproduced image 109 with high efficiency.
Referring to
The beam splitter 107 transfers an incident beam to the spatial light modulator 105, and transfers a beam, reflected by the spatial light modulator 105, to the optical part 106.
Referring to
As illustrated in
Δφ=CγlV (1)
where C indicates a specific constant, l indicates a light traveling distance, and V indicates an external voltage.
Particularly, when an electro-optic coefficient (γ) is large, a phase may be easily shifted, and all incident light is transmitted by changing linear polarization by 90 degrees in half-wavelength phase shift. Such a light passes through a linear polarizer 207, and thus, a light modulation is completed.
In order to efficiently perform oval polarization by using anisotropy of a light modulation thin film, the polarization direction of a linear polarizer in a light incident part may be disposed to be inclined by 45 degrees with respect to a light axis.
The spatial light modulator controls a light transmittance by applying an electric signal to each pixel. However, when there is no electric signal, namely, when in an off state, since a polymer thin film or a dielectric thin film has optical isotropy, a light that has been linearly polarized through one linear polarizer cannot pass through another vertically-polarized polarizer, and thus, a light is not transmitted. In this case, when an electric signal is applied, namely, when in an on state, a refractive index is changed by the electro-optic effect, and thus, a linearly-polarized light is ovally polarized while passing through a thin film to pass through another linear polarizer.
As described above, the spatial light modulator effectively controls an on/off state on the transmission of a light by applying an electric signal to each pixel, and moreover, controls a light transmittance intensity by dividing electric signal intensity. Accordingly, the system becomes a spatial light modulator that modulates an intensity and a phase of a light.
The spatial light modulator efficiently controls each pixel by using a multi-cell signal processing technology.
Referring to
Referring to
A unit pixel in the spatial light modulation panel layer includes a light modulation layer 401 formed with a polymer thin film or a dielectric thin film, metal lines 402 for addressing each pixel, and a thin film transistor 403.
As illustrated in
In
A method of forming the light modulation layer includes: a process that deposits a lower transparent electrode 405 on a transparent substrate 404; a process that deposits a polymer thin film 406 or a dielectric thin film 406 on the lower transparent electrode 405; an operation that forms an upper transparent electrode 407 on the polymer thin film 406 or dielectric thin film 406; and a process that performs patterning for each unit pixel.
The transparent electrode 405 may include an oxide electrode such as ITO, SnO2, and ZnO2. The transparent electrode 405 may be formed on the amorphous or isotropic crystal transparent substrate 404 in a thin film deposition process such as an electron beam deposition process or a sputter process.
The polymer thin film 406 or the dielectric thin film 406 has a very large electro-optic coefficient of about tens pm/V and a high switching speed of nanosecond or less, and thus can efficiently modulate a light with an electric field.
The polymer thin film 306 includes at least one of polymer materials, which show very large optical anisotropy when an electric field is applied, such as PMMA, P2ANS, DANS/MMA, NPT/epoxy, and PUR/AZO.
The dielectric thin film 306 includes dielectric such as LiNbO3, LiTaO3, NH4H2PO4, KH2PO4, perobarskite-based material such as BaTiO3, and PLZT-based material with very large electro-optic effect.
In the embodiment of the present invention, a material used in the spatial light modulator is not limited to polymer or dielectric, and may include various materials with large electro-optic coefficient. Herein, the material may include semiconductor materials such as GaAs, InP, and CdS.
The polymer thin film 406 and the dielectric thin film 406 may be formed by a chemical deposition process such as a sol-gel process or a Chemical Vapor Deposition (CVD) process, or a physical deposition process such as a sputter process.
The spatial light modulator with the polymer thin film 406 or dielectric thin film 406 enables high-speed switching and the integrating of pixels at a high density compared to the existing LCD devices, in characteristic.
A unit pixel in the spatial light modulation panel layer includes a polymer thin film 501 or dielectric thin film 501, metal lines 502 and a metal electrode 503 for addressing each pixel, and a thin film transistor 403.
As illustrated in
In the spatial light modulator, on/off on the transmission of a light is determined by a voltage that is applied between two electrodes, and it can be seen that an on state of the transmission of a light indicates a case where only one voltage is applied.
That is, when a voltage difference occurs between two electrodes and thus an electric field is applied, as illustrated in
A method of forming the light modulation layer includes: a process that deposits a polymer thin film 506 or a dielectric thin film 506 on a transparent electrode 505; an operation that forms a plurality of upper transparent electrodes 507 on the polymer thin film 506 or dielectric thin film 506; and a process that performs patterning for each unit pixel.
Each of the upper transparent electrodes 507 may include an oxide electrode such as ITO, SnO2, and ZnO2. The transparent substrate 505 includes an amorphous or isotropic crystal transparent substrate.
The upper transparent electrodes 507 may be formed by a thin film deposition process such as an electron beam deposition process or a sputter process. The polymer thin film 506 and the dielectric thin film 506 may be formed by a chemical deposition process such as a sol-gel process or a CVD process, or a physical deposition process such as a sputter process.
The spatial light modulator is formed with no vertical and horizontal polarizers. A method of manufacturing the spatial light modulator includes: a process that deposits a polymer thin film 603 or a dielectric thin film 603 on a transparent substrate 601 or a lower transparent electrode 602/the transparent substrate 601; a process that performs patterning for each pixel; an operation that forms an upper transparent electrode 604; and an operation that forms a thin film transistor in each pixel. The lower transparent electrode 602, polymer thin film/dielectric thin film 603 and upper transparent electrode 604 form a region having the electro-optic effect. The lower transparent electrode 602, polymer thin film/dielectric thin film 603, upper transparent electrode 604, and a polymer thin film/dielectric thin film 603 isolated by a light blocking layer 606 form a region having no electro-optic effect. Also, a light reflective layer 605 is used for efficiently combining lights that have passed through two layers.
It is apparent to those skilled in the art that the spatial light modulator with no polarization principle is not limited to the Mach-Zehnder interference principle. That is, various schemes for controlling the phase and intensity of a light may be used in forming the spatial light modulator.
As shown in
As shown in
A principle of realizing the high-resolution 3D image will be described below.
In realizing the high-resolution 3D image, a first operation and a second operation are sequentially repeated in a divided region. Herein, the first operation displays a hologram interference pattern on a spatial light modulator and simultaneously irradiates a reproduced light on the spatial light modulator to reproduce a 3D image. The second operation moves the spatial light modulator by one stage and then displays a hologram fringe pattern, generated suitably for the moved spatial light modulator, to reproduce a 3D image. In this case, when it is assumed that a 3D image before division is one frame 3D image, a sequentially-reproduced 3D image is integrated in one frame before division, thereby realizing a high-resolution 3D image.
A principle of realizing the high-resolution 3D image will be described below.
As illustrated in
As described above, the holographic display device according to the embodiments of the present invention, which integrates an image with the spatial light modulator having a fast response time and provides a high-resolution 3D image, solves difficulties in realizing the high-resolution 3D image and reproduces a vivid 3D image.
In the high-resolution holographic display according to the embodiments of the present invention, moreover, as the spatial light modulator using the polymer thin film or the dielectric thin film is developed, the high-density spatial light modulator having a fast response time can be realized.
The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-0072066 | Jul 2010 | KR | national |
| 10-2010-0125081 | Dec 2010 | KR | national |
This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application Nos. 10-2010-0072066, filed on Jul. 26, 2010, and 10-2010-0125081, filed on Dec. 8, 2010, the entire contents of which are hereby incorporated by reference.
