JP2010507826A - Holographic display device including magneto-optical spatial light modulator - Google Patents

Abstract

  The holographic display device comprises at least one magneto-optical spatial light modulator (MOSLM). The holographic display device may comprise a first MOSLM (53, 54) and a second MOSLM (56, 57), wherein the first and second MOSLM encode a hologram and A holographic reconstruction is generated. The advantage of the device is that it can encode the hologram at high speed.

Description

  The present invention relates to a holographic display device in which a computer video hologram (CGH) is encoded, the display comprising at least one magneto-optical SLM. The display generates a 3D holographic reconstruction.

  Computer video holograms (CGH) are encoded in one or more spatial light modulators (SLMs). The SLM includes controllable cells. The cell modulates the amplitude and / or phase of the light by encoding the hologram value corresponding to the video hologram. The CGH may be calculated, for example, by coherent ray tracing, may be calculated by simulating interference between the light reflected by the scene and the reference wave, or may be calculated by Fourier transform or Fresnel transform. Also good. An ideal SLM can represent any complex number. That is, the amplitude and phase of the incident light wave can be controlled separately. However, a typical SLM controls only one characteristic of amplitude or phase, but with the undesirable side effect of affecting the other characteristic. Various methods of modulating the amplitude or phase of light are well known, such as an electrical addressed liquid crystal SLM, an optical addressed liquid crystal SLM, a micromirror device, or an acousto-optic modulator. The modulation of light may be spatially continuous or may be composed of individually addressable cells. The cells are arranged in one or two dimensions and are binary, multi-valued or continuous. One type of known SLM is the magneto-optical SLM (MOSLM). In MOSLM, the current flows through the coil of the display to control the magnetic field, which affects the polarization state of the polarized light propagating through the display pixels. Therefore, MOSLM is a kind of electric address type SLM.

  In this document, the term “encoding” refers to a method of providing a region of a spatial light modulator with control values for encoding a hologram so that a 3D scene can be reconstructed from an SLM. Define. “SLM encoding a hologram” means that the hologram is encoded in the SLM.

  In contrast to pure autostereoscopic displays, video holograms allow the viewer to see an optical reconstruction of the light wavefront of a three-dimensional scene. The 3D scene is reconstructed in a space that extends between the viewer's eyes and the spatial light modulator (SLM), and possibly behind the SLM. The SLM can also be encoded with a video hologram so that the viewer can see the reconstructed 3D scene object in front of the SLM and other objects on or behind the SLM.

  The cell of the spatial light modulator is preferably a transmissive cell through which the light passes, and the ray can generate interference at least at a predetermined location and at a location that exceeds the spatial coherence length by several millimeters. . This allows holographic reconstruction with sufficient resolution in at least one dimension. This type of light is called "sufficiently coherent light".

  In order to ensure sufficient temporal coherence, the spectrum of light emitted by the light source should be limited to a sufficiently narrow wavelength band, i.e. almost monochromatic. The spectral bandwidth of high-brightness LEDs is sufficiently narrow to ensure temporal coherence of holographic reconstruction. The diffraction angle at the SLM is proportional to wavelength, meaning that only a monochromatic source will result in a clear reconstruction of the object points. Spectral expansion will disperse object points and smear in object reconstruction. The spectrum of the laser light source can be considered as a single color. The spectral line width of the LED is narrow enough to promote good reconstruction.

  Spatial coherence is related to the lateral extent of the light source. Conventional light sources such as LEDs and cold cathode fluorescent lamps (CCFLs) can meet these requirements if they emit light through a sufficiently narrow aperture. The light from the laser light source can be viewed as radiation from a point light source within the diffraction limit, resulting in a clear reconstruction of the object depending on the mode purity. That is, each object point is reconstructed as a point within the diffraction limit.

  Light from a spatially incoherent light source expands horizontally and causes smearing on the reconstructed object. The amount of smear is given by the expanded size of the reconstructed object point at a given position. In order to use a spatially incoherent light source for hologram reconstruction, a trade-off between brightness and the lateral spread limitation of the light source with the aperture should be found. The smaller the light source, the better the spatial coherence.

  A linear light source can be regarded as a point light source if viewed from a right angle with respect to the longitudinal extension. Thus, a light wave can propagate coherently in that direction, but propagates incoherently in all other directions.

  In general, a hologram reconstructs a scene holographically by coherent superposition of waves in the horizontal and vertical directions. Such video holograms are called full parallax holographs. The reconstructed object can be seen as a real object with motion parallax in the horizontal and vertical directions. However, a large viewing angle requires high resolution in both the horizontal and vertical directions of the SLM.

  Often, the demands on SLM are reduced by limitations on horizontal parallax only (HPO) holograms. Holographic reconstruction occurs only in the horizontal direction, while there is no holographic reconstruction in the vertical direction. This is due to the reconstructed object having horizontal motion parallax. The transmissive view does not change up in the vertical direction. The resolution of the SLM in the vertical direction required by the HPO hologram is less than that of the full parallax hologram. Holograms with only vertical parallax (VPO) are possible but rare. Holographic reconstruction occurs only in the vertical direction, resulting in a reconstructed object with vertical motion parallax. There is no motion parallax in the horizontal direction. Different transparent views for the right and left eyes should be generated separately.

  U.S. Pat. No. 6,057,056, filed by the applicant and incorporated herein by reference, describes an apparatus for reconstructing a three-dimensional scene by a method of sufficient coherent light diffraction. The apparatus includes a point light source or line light source, a lens for focusing the light, and a spatial light modulator. In contrast to conventional holographic displays, SLM in transmissive mode reconstructs a 3D scene in at least one “virtual observer window” (discussing this word and related techniques, See Appendix i and ii). A virtual observer window can be positioned at a single diffraction order, allowing the observer to fully reconstruct the 3D scene in a frustum-shaped reconstruction space that extends between the surface of the SLM and the virtual observer window. As each can be seen, each virtual observer window is positioned close to the observer's eye and its size is limited. In order to allow fault-free holographic reconstruction, the size of the virtual observer window should not exceed the period interval of one diffraction order of the reconstruction. However, it must be at least large enough for the viewer to see the entire reconstruction of the 3D scene through the window. Other eyes can be viewed through the same virtual observer window, or a second virtual observer window generated by the second light source may be assigned in the same manner. Here, the visible region, which is typically somewhat larger, is limited to the locally located virtual observer window. Known miniaturization solutions reconstruct large areas resulting from the high resolution of conventional SLM surfaces and reduce them to the size of the virtual observer window. This is because the reduced diffraction angle for geometric reasons and the resolution of current SLMs is sufficient to achieve high quality real-time holographic reconstruction using reasonable consumer-level computing devices. The effect is that the level is low.

  However, problems arise with the frame rate generated by the holographic display, especially when two or more viewers of the display are considered. In the hologram generation method described in Patent Document 1, a virtual observer window (VOW) is generated. When the VOW is positioned on the observer's eye, the reconstructed object can be observed. One VOW is required for each eye of each observer. When VOW, red (R), green (G), and blue (B) are generated in order, a high frame rate is required. “In order” means that the light for colors R, G, and B are turned on and off in sequence, and the same SLM cell is used in turn to encode the R, G, and B light for the pixels on the SLM. To do. A frame rate for each eye of at least 30 Hz is required to avoid flicker perception. As an example, for 3 observers, a frame rate of 30 Hz * 2 eyes * 3 observers * 3 colors = 540 Hz is required. This is much faster than the frame rate of liquid crystal (LC) SLMs. Even for a single observer, an implicit frame rate of 180 Hz is the limit achievable with existing liquid crystal SLM technology. Some display artifacts occur for rapidly changing images. Known high speed microelectromechanical system (MEMS) SLMs do not provide high resolution phase modulation. For these techniques, the characteristic switching time is about 10 ms for LC and about 10 μs for MEMS. Thus, known devices have significant problems in displaying holographic images to multiple viewers with full complex holographic encoding, especially when the images are color. For a single observer, a frame rate faster than that obtainable using LC technology is useful in applications involving fast motion such as video games, watching sports or watching action movies, or military software. It is.

  SLMs (including the case of a pair of consecutive SLMs) that allow independent amplitude and phase modulation are advantageous for applications in holographic displays. Complex value holograms have high reconstruction quality and high brightness compared to pure amplitude holograms or pure phase holograms. Conventional Faraday effect magneto-optical SLMs (MOSLMs) are well known, but they only modulate the amplitude of the transmitted light and are not used in generating holograms. Such SLMs are reported, for example, in US Pat. No. 6,028,028, incorporated by reference herein, by the Panorama Labs of Rockefeller Center, 1230 Avenue of the Americas, 7th Floor, New York, NY 10020 USA (www.panoramalabs.com). ing. However, other such MOSLMs are well known.

  Accordingly, there is a need for a holographic display device and an SLM for the holographic display device that can accommodate high frame rates and preferably can separately encode phase and amplitude information.

International Publication No. 2004/044659 (US Patent Application No. 2006/0055994) International Publication No. WO2005 / 076714A2

  In a first aspect, a holographic display device is provided that includes at least one magneto-optical SLM.

  The holographic display device may include a first MOSLM and a second MOSLM. The first MOSLM and the second MOSLM encode the hologram, and the holographic reconstruction is generated by the device. A holographic display device is a display device in which the first MOSLM and the second MOSLM modulate the amplitude and phase of an array of hologram pixels in an independently controlled manner. The holographic display device has a first MOSLM that is small and sequentially used to modulate the amplitude and phase of light so that a complex number composed of amplitude and phase is encoded per pixel in the transmitted light. A small combination of the second MOSLMs may be included.

  The holographic display device may include a small combination of a MOSLM and a small light source with sufficient coherence, which combination can generate a three-dimensional image under appropriate lighting conditions.

  The holographic display device may include a high magnification 3D image display device component that incorporates a small combination of one or two MOSLMs along with a holographic reconstruction of the object.

  The holographic display device may incorporate a small combination of one or two MOSLMs, which may be used as a projector.

  The holographic display device may have at least one SLM encoding a hologram, and the holographic reconstruction is generated by the device.

  The holographic display device may be a display device that modulates light using the Faraday effect. The holographic display device may be a display device in which the Faraday effect is realized using a magnetic photonic crystal. The holographic display device may be a display device in which the Faraday effect is realized using doped glass fibers. The holographic display device may be a display device in which the Faraday effect is realized using a magneto-optical film.

  The holographic display device may be a display device in which the holographic reconstruction is visible through a virtual observer window.

  The holographic display device may be a display device in which the virtual observer window is tiled using spatial multiplexing or time multiplexing.

  The holographic display device may be a display device that is operable to re-encode the holograms on the medium in time series, including holograms for the viewer's left and right eyes.

  A holographic display device is a display device in which the display is operable to re-encode holograms on a medium containing holograms in time series for the left and right eyes of each of two or more observers. May be.

  The holographic display device may be a display device in which the display has an element for beam steering or a beam splitter.

  The holographic display device may be a display device whose display has a CIAD layer.

  The holographic display device may be a display device whose display has eye tracking.

  The holographic display device may be a display device in which the display is illuminated by a backlight and a microlens array. The microlens array may provide local coherence over a small area of the display, which is the part of the display that encodes information used in reconstructing a given point of the reconstructed object. The display may include a reflective polarizer. The display may include a prismatic optical film.

  The holographic display device may have a light emitting diode as a light source.

  The holographic display device may be a television. The holographic display device may be a monitor. The holographic display device may be portable.

  In a further aspect, a method for manufacturing a holographic display device is provided. The method includes the steps of providing a glass substrate and successively printing or creating a layer for MOSLM on the substrate.

  In a further aspect, a method is provided for generating a holographic reconstruction that includes using a display device as described above.

  In a further aspect, a holographic display device including a magneto-optical SLM is provided. The SLM encodes the hologram and the holographic reconstruction is generated by the device. The holographic display device may be a television. The holographic display device may be a monitor. The holographic display device may be a laptop computer. The holographic display device may be a mobile phone. The holographic display device may be a PDA. The holographic display device may be a digital music player. The holographic display device may modulate light using the Faraday effect. The holographic display device may modulate light using the Faraday effect realized using a magnetic photonic crystal. The holographic display device may modulate light using the Faraday effect realized using doped glass fibers. The holographic display device may modulate light using the Faraday effect realized using a magneto-optical film. The holographic display device may be illuminated by a backlight and a microlens array. The backlight of the holographic display device may include at least one reflective polarizer for the linear polarization state of light. The backlight of the holographic display device may include at least one reflective polarizer for the circular polarization state of light. The microlens array of a holographic display device may provide local coherence over a small area of the display that encodes information used in reconstructing a given point of the reconstructed object Is part of. The SLM of the holographic display device may provide phase encoding. The holographic display device SLM may provide amplitude encoding. The holographic reconstruction of the holographic display device may be visible through a virtual observer window. The virtual observer window of the holographic display device may be tiled using spatial multiplexing or time multiplexing. The holographic display device may be operable so that the holographic reconstruction can be properly viewed only when the viewer's eyes are approximately in the image plane of the light source. In the holographic display device, the size of the reconstructed three-dimensional scene is a function of the size of the medium including the hologram, and the reconstructed three-dimensional scene is a virtual image through which the reconstructed three-dimensional scene is viewed. It may be a display device as it exists anywhere within the volume defined by the medium containing the observer window and hologram. The holographic display device may encode a hologram that includes an area having information needed to reconstruct a single point of a three-dimensional scene, which is visible from a defined viewing position. is there. A region is a) encoding information for a single point in the reconstructed scene, b) is the only region of the hologram encoded with information for that point, and c) is sized to form part of the entire hologram. The size is limited such that multiple reconstructions of the point due to higher order diffraction are not visible at the defined viewing position. The holographic display device may be operable to re-encode the holograms on the medium containing the holograms in time series for the left and right eyes of the viewer. The holographic display device may be operable to re-encode the holograms on the medium including the holograms in time series for the left and right eyes of each of two or more viewers. The holographic display device may be operable such that the holographic reconstruction is a hologram Fresnel transform rather than a hologram Fourier transform. The holographic display device may encode a hologram generated by determining a wavefront that is approximately at the position of the viewer's eye generated by the actual version of the reconstructed object. The holographic display device may have a prism element for beam steering. The holographic display device may have a CIAD layer. The holographic display device may have eye tracking.

  In a further aspect, a method is provided for generating a holographic reconstruction that includes using a display device as described above.

  In a further aspect, a holographic display device is provided that includes a first MOSLM and a second MOSLM. The first MOSLM and the second MOSLM encode the hologram, and the holographic reconstruction is generated by the device. The holographic display device may be a display device that modulates the amplitude and phase of the array of hologram pixels in a manner in which the first MOSLM and the second MOSLM are independently controlled. The holographic display device may be a display device in which one MOSLM modulates the amplitude of the array of hologram pixels and the other MOSLM modulates the phase of the array of hologram pixels. A holographic display device is a display in which one MOSLM modulates a first combination of amplitude and phase of an array of hologram pixels and the other MOSLM modulates a second different combination of amplitude and phase of an array of hologram pixels. It may be a device. A holographic display device may be a display device in which light propagating in the device is first encoded with respect to phase and then encoded with respect to amplitude. The holographic display device may be a television. The holographic display device may be a monitor. The holographic display device may be a laptop computer. The holographic display device may be a mobile phone. The holographic display device may be a PDA. The holographic display device may be a digital music player. The holographic display device may be a display device in which each MOSLM modulates light using the Faraday effect. The holographic display device may be a display device that modulates light using the Faraday effect realized using a magnetophotonic crystal in at least one MOSLM. The holographic display device may be a display device that modulates light using the Faraday effect realized using doped glass fibers in at least one MOSLM. The holographic display device may be a display device that modulates light using the Faraday effect realized using a magneto-optical film in at least one MOSLM. The holographic display device may be a display device in which a separation layer separates one MOSLM from the other MOSLM. The holographic display device may be a display device that includes an isolation layer that is thin enough to prevent the electromagnetic field of one MOSLM from adversely affecting the performance of the other MOSLM. The holographic display device may be a display device in which the separation layer further provides mechanical support for at least one MOSLM. The holographic display device may be a display device having a separation layer of about 10 microns to 100 microns or less. The holographic display device may be a display device that encodes a hologram and allows a holographic reconstruction to be generated. The holographic display device may be a display device in which the display is illuminated by a backlight and a microlens array. The holographic display device may be a display device in which the backlight includes at least one reflective polarizer for the linear polarization state of light. The holographic display device may be a display device in which the backlight includes at least one reflective polarizer for the circular polarization state of light. A holographic display device may be a display device in which a microlens array provides local coherence over a small area of the display, which area is information used in reconstructing a given point of the reconstructed object. Is part of a display that encodes The holographic display device may be a display device in which the holographic reconstruction is visible through a virtual observer window. The holographic display device may be a display device in which the virtual observer window is tiled using spatial multiplexing or time multiplexing. The holographic display device may be a display device that can properly view holographic reconstruction only when the viewer's eyes are positioned approximately in the image plane of the light source. In the holographic display device, the size of the reconstructed three-dimensional scene is a function of the size of the medium including the hologram, and the reconstructed three-dimensional scene is a virtual image through which the reconstructed three-dimensional scene is viewed. It may be a display device that can be located anywhere within the volume defined by the medium containing the observer window and the hologram. A holographic display device may be a display device that encodes a hologram that includes an area having information required for the display to reconstruct a single point of a three-dimensional scene, the point being defined. Visible from the viewing position. That region (a) encodes information for a single point in the reconstructed scene, (b) is the only region of the hologram encoded with information for that point, and (c) forms part of the entire hologram. So that the size is limited. The size is such that multiple reconstructions of points due to higher order diffraction are not visible at a defined viewing position. The holographic display device may be a display device that is operable to re-encode time-series holograms on a medium that contains holograms for the viewer's left and right eyes. A holographic display device is a display device in which the display is operable to re-encode holograms on a medium containing holograms in time series for the left and right eyes of each of two or more observers. May be. The holographic display device may be a display device in which the display is operable such that the holographic reconstruction is not a Fourier transform of the hologram but a Fresnel transform of the hologram. A holographic display device may be a display device that encodes a hologram generated by determining a wavefront that is approximately at the position of the viewer's eye generated by the actual version of the object from which the display is reconstructed. Good. The holographic display device may be a display device in which a prism element for beam steering is present. The holographic display device may be a display device having a CIAD layer. The holographic display device may be a display device with eye tracking.

  In a further aspect, a method for manufacturing a holographic display device is provided. The method includes providing a glass substrate and sequentially printing or creating a layer for the first MOSLM and a layer for the second MOSLM on the substrate.

  In a further aspect, a method is provided for generating a holographic reconstruction that includes using a display device as described above.

  In a further aspect, a compact combination of MOSLM and a small light source with sufficient coherence is provided. The combination can generate a three-dimensional image under appropriate lighting conditions. The small combination may be a combination that does not require the imaging optical device. A small combination may be a combination in which the total thickness of the elements of the device is less than 3 cm. The small combination may be a combination in which a soft aperture exists for the small combination of pixels.

  In a further aspect, a small combination of two MOSLMs used to modulate the amplitude and phase of light in a small and sequential manner so that a complex number composed of amplitude and phase is encoded per pixel in transmitted light. Is provided. The small combination may be a combination that does not require the imaging optical device. A small combination may be a combination in which the total thickness of the elements of the device is less than 3 cm. The small combination may be a combination in which there is a soft aperture for the pixel of the device. A small combination may be a combination in which two MOSLMs are directly coupled or glued by aligned pixels. A small combination may be a combination in which the separation of the two MOSLMs is about 10 microns to 100 microns or less. The small combination may be a combination in which diffraction of light passing from one MOSLM to the other MOSLM exists in the Fresnel diffraction phenomenon instead of the far-field diffraction phenomenon. The small combination may be a combination in which a lens array exists between two MOSLMs so that each lens forms an image of a first SLM pixel on each second SLM pixel. The small combination may be a combination in which the aperture width of the first MOSLM pixel is such that the pixel crosstalk is minimized. The small combination may be a combination in which the aperture width of the first MOSLM pixel is such that the pixel crosstalk in the Fraunhofer diffraction phenomenon with respect to the second MOSLM pixel is minimized. The small combination may be a combination in which a fiber optic faceplate is used to image a first MOSLM pixel onto a second MOSLM pixel.

  In a further aspect, a high magnification 3D image display device component is provided that incorporates a small combination of one or two MOSLMs along with holographic reconstruction of the object. The display device component may include a small combination of one or two MOSLMs and a small light source with sufficient coherence. The display device component may include a small combination of one or two MOSLMs and a small light source with sufficient coherence so that the small combination can generate a three-dimensional image. The display device component may include a small combination of one or two MOSLMs and a small light source of sufficient coherence, the light source being magnified 10-60 times by the lens array. The display device component may include a small combination of one or two MOSLMs and a small light source of sufficient coherence, with at least one MOSLM positioned within 30 mm from the light source. The display device component may include a small combination of one or two MOSLMs and a small light source with sufficient coherence so that the small combination can generate a three-dimensional image that can be viewed in the VOW. The display device component may be a component in which the VOW is limited to the first order diffraction of the Fourier spectrum of the information encoded in the SLM. The VOW of the display may be trackable or non-trackable. The VOW of the display may be expanded by tiling the VOW by spatial multiplexing or time multiplexing. The display device component may include a small combination of one or two MOSLMs and a small light source with sufficient coherence, and the light source of the light source array has only partial spatial coherence. There may be a PDA that includes the device component. There may be a mobile phone that includes the device component. Calculation of holograms encoded in the SLM performed in the external encoding unit may be performed, and display data is sent to the device component by the external encoding unit, allowing display of the holographically generated three-dimensional image. To do.

  In a further aspect, a method for manufacturing a holographic display device is provided. The method includes providing a glass substrate and sequentially printing or creating a layer for one or two MOSLMs on the substrate. The device includes a high magnification 3D image display device component that incorporates a small combination of one or two MOSLMs along with holographic reconstruction of the object.

  In a further aspect, a method is provided for generating a holographic reconstruction that includes using a display device component as described above.

  By “SLM encoding a hologram” is meant that the hologram is encoded in the SLM.

FIG. 1 shows a holographic display device including a single MOSLM. FIG. 2 illustrates a holographic display device that includes a pair of components, each including a single MOSLM. It is a figure which shows a part of MOSLM pixel element which concerns on a prior art. It is a figure which shows the holographic display which concerns on a prior art. FIG. 3 is a cross-sectional view illustrating three pixels of a specific example of a holographic display device that includes a pair of components, each including a single MOSLM. FIG. 2 shows a holographic display. It is a figure which shows the holographic display suitable for size reduction. FIG. 6 shows a manufacturing process used in manufacturing a microcoil array according to the prior art. FIG. 6 shows a manufacturing process used in manufacturing a microcoil array according to the prior art. It is a figure which shows a holographic display apparatus. FIG. 2 shows a holographic display device incorporating two MOSLMs for sequentially encoding amplitude and phase. FIG. 1 shows a holographic display device including a single MOSLM. It is a figure which shows a specific example of the holographic display which concerns on one implementation. FIG. 2 shows a holographic display device incorporating two MOSLMs for sequentially encoding amplitude and phase. It is a graph which shows the diffraction simulation result acquired using MathCad (trademark). It is a graph which shows the diffraction simulation result acquired using MathCad (trademark). It is a graph which shows the diffraction simulation result acquired using MathCad (trademark). It is a figure which shows the structure of two MOSLM which includes the lens array layer which concerns on one implementation example in between. It is a figure which shows the diffraction process which may be performed when light propagates from one MOSLM to the second MOSLM. FIG. 6 illustrates an example of a holographic display component according to an implementation. It is a figure which shows a beam steering element. It is a figure which shows a beam steering element. 2 is a schematic diagram illustrating a holographic display including a light source of a 2D light source array, a lens of a 2D lens array, an SLM, and a beam splitter. The beam splitter splits the light emitted from the SLM into two light beams, which illuminate the left-eye virtual observer window (VOWL) and the right-eye virtual observer window (VOWR), respectively. FIG. 2 is a schematic diagram illustrating a holographic display including two light sources of a light source array and two lenses of a lens array, an SLM and a beam splitter. The beam splitter splits the light emitted from the SLM into two light beams, which illuminate the left-eye virtual observer window (VOWL) and the right-eye virtual observer window (VOWR), respectively. It is a cross-sectional view showing a prism beam steering element.

Next, various implementation examples will be described.
A. Holographic display device with magneto-optical SLM The present implementation provides a holographic display device with magneto-optical SLM, the combination of which can generate a three-dimensional image under appropriate illumination conditions. The display may be illuminated by multiple light sources or a single light source. The holographic display may be used in a television, monitor, laptop computer, mobile phone, PDA, digital music player or any other device where a display is commonly used.

  The implementation relates to an SLM for modulation of light, ie amplitude or phase, or a combination of amplitude and phase. In particular, this implementation relates to an SLM based on the modulation of light by the Faraday effect. The SLM may be used in a holographic display.

The Faraday effect appears as rotation of linearly polarized light in the medium when a magnetic field is applied in the direction of light propagation. This is described quantitatively by the following formula:
α = VLH (1)
Where α is the polarization rotation angle, V is the Verde constant, L is the length of the medium, and H is the magnetic field strength. The Faraday effect occurs when anisotropy is given by a magnetic field. The magnetic field is an axial vector indicating sensitivity in the rotation direction. Accordingly, the left and right circularly polarized states are no longer in a degenerate state, and thus are affected by different refractive indexes and different phase shifts in the medium. Since linearly polarized light consists of left circularly polarized light and right circularly polarized light, when the circular components are combined again to form linearly polarized light, rotation of the linearly polarized light angle occurs due to different phase shifts of these components.

  In general, the Verde constant V is small and an effective rotation angle α requires a long length L or a large magnetic field H. The Faraday effect is greatly increased in magneto-photonic liquid crystals that include a stack of magneto-optical layers. This facilitates using the Faraday effect in a thin structure with a small magnetic field for the SLM. This is explained in “A Presentation for Investors” by Panorama Labs of Rockefeller Center, 1230 Avenue of the Americas, 7th Floor, New York, NY 10020 USA (www.panoramalabs.com), for example, obtained from the Internet (this The literature is incorporated herein by reference). This document will be available from the site web.archive.org.

  Panorama Labs reports an SLM that uses the Faraday effect as shown in FIG. This includes an array of magnetic photonic crystals, input / output polarizers and coils. One coil exists for each pixel of the SLM having a pixel pitch of 16 μm. Magnetophotonic crystals are composed of a stack of magneto-optical layers that improve the Faraday effect compared to a single layer. When a current is applied, the coil generates a local magnetic field in each pixel, which causes a rotation of the linear polarization of light passing through that pixel. The output polarizer transmits only a specific polarization angle. Therefore, the transmittance of each pixel is modulated by the current in the coil. FIG. 3 shows one pixel of the SLM that includes a polarizer, a magnetic photonic liquid crystal (MPC), a coil, and an analyzer. The constant input intensity p0 is modulated to give an output intensity function P (t) that depends on time (t).

  The advantage of Faraday effect SLM compared to LC-SLM or MEMS-SLM is fast response time. Panorama Labs reported a response time of 20 ns in a Faraday effect SLM. It is much faster than LC-SLM (about 10 ms) or MEMS-SLM (about 10 μs). MOSLM is used for electronic holographic displays. In one method for a holographic display, a virtual observer window (VOW) is generated. When the VOW is positioned on one eye of the observer, the reconstructed object is visible. One VOW is required for each eye of each observer. When VOW and colors R, G, and B are generated in order, a high frame rate is required. To avoid flickering, a frame rate for each eye of at least 30 Hz is required. As an example, for 3 observers, a frame rate of 30 Hz * 2 eyes * 3 observers * 3 colors = 540 Hz is required. This is much faster than the LC-SLM frame rate. Known high speed MEMS-SLMs do not provide high resolution phase modulation. SLMs that modulate amplitude and phase are advantageous for applications in electronic holographic displays. Complex value holograms have higher reconstruction quality and higher brightness than pure amplitude holograms or pure phase holograms. The only observable effect of the conventional Faraday effect SLM disclosed by Panorama Labs in FIG. 3 is the modulation of the amplitude of the transmitted light. Furthermore, the conventional Faraday effect SLM disclosed by Panorama Labs in FIG. 3 is not illuminated with sufficient coherence light to generate a three-dimensional image.

  In FIG. 1, an example of an implementation will be described. Reference numeral 10 denotes an illumination device for providing illumination in a planar area. Here, the illumination has sufficient coherence so that a three-dimensional image can be generated. An example is disclosed in U.S. Patent Application Publication No. 2006/250671 to the example of a large area video hologram that is incorporated herein by reference. An example of a large area video hologram is reproduced in FIG. An apparatus such as 10 may take the form of an array of white light sources such as white light emitting diodes or cold cathode fluorescent lamps that emit light incident on a focusing system that may be small, such as a lenticular array or a microlens array. Good. Alternatively, the light source for 10 may consist of red, green and blue lasers or red, green and blue light emitting diodes that emit sufficiently coherent light. However, non-laser light sources (eg, light emitting diodes, OLEDs, cold cathode fluorescent lamps) with sufficient spatial coherence are preferred over laser light sources. Laser light sources can cause laser speckle in holographic reconstruction, are relatively expensive, and can be viewed by holographic display viewers or those who are engaged in the assembly of holographic display devices. Disadvantages such as having an expected safety problem with respect to the possibility of damage.

  Element 10 may include one or two prismatic optical films to increase the brightness of the display. Such films are disclosed, for example, in US Pat. No. 5,056,892 and US Pat. No. 5,919,551, although other films are well known.

  The hologram generator 15 has a size range from a screen size of 1 cm diagonal (or smaller) such as a sub-display of a mobile phone to a screen of 1 m diagonal (or larger) of a large indoor display. Also good. Therefore, the elements 10 to 14 may have a total thickness from 1 mm or less to several tens of cm or more in the case of a large indoor display. The element 11 is a polarizing optical element or a set of polarizing optical elements. An example is a linear polarizer sheet. A further example is a reflective polarizer that transmits one linear polarization state and reflects an orthogonal linear polarization state. Such sheets are described, for example, in US Pat. No. 5,828,488, but other sheets are well known. A further example is a reflective polarizer that transmits one circular polarization state and reflects an orthogonal circular polarization state. Such sheets are described, for example, in US Pat. No. 6,181,395, but other sheets are well known. The color filter may not be required when a color light source is used, but the element 12 is a color filter so that colored light pixels such as red light, green light and blue light are emitted to the element 13. It may be composed of an array. The element 13 is a magneto-optical SLM. In its simplest form, element 13 is an array of coils of conductive material, each coil being used to individually control the magnetic field experienced by light through the corresponding pixel of the display. As described by equation (1), such light can pass through a medium having an effective Verde constant V such that linearly polarized light may experience an effective rotation α as it passes through the medium. Control becomes easy. The medium may be in the form of a doped glass fiber cylinder or similar shape, as described in US Patent Application Publication No. 2005/0201705. Alternatively, the medium may be in the form of a magneto-optical film or a magneto-photonic crystal layer as described in International Publication No. WO 2005/122479 A2. Light emitted from the medium passes through a polarizing layer 14 such as a linear polarizer sheet.

  When element 11 is a reflective polarizer sheet for the circular polarization state of light, circularly polarized light is transmitted from element 11 to element 12, while orthogonally polarized light is reflected because it may be reused. Returning to element 10, during that time, the polarization may change to a state that is transmitted by element 11. In this example, the polarizer sheet 14 after the element 13 consists of a quarter wave plate that converts circularly polarized light into linearly polarized light, followed by a linearly polarizing sheet. The quarter wave plate may function over the visible spectrum as described, for example, in US Pat. No. 7,054,049. Other quarter wave plates that function over the visible spectrum are well known. The linear polarizing sheet 14 rotates azimuth so that the polarization state of all pixels in the array remains unchanged and the display is dark because H is zero across the array of pixels when no current flows through the coil of the array. It may be arranged at an angle. Other configurations will be apparent to those skilled in the art. When a current flows through the coils of the array, the polarization state may change for each pixel, and thus an image such as a color image can be displayed. As described elsewhere in this specification, when the input polarization state of light to the magneto-optical SLM (MOSLM) is a pure circular polarization state, the current flows through the coil, so that the phase is in the circular polarization state. Encoding is possible. Such phase encoding enables a hologram with encoded phase information.

  When element 11 is a reflective polarizer sheet for the linear polarization state of light, linearly polarized light is transmitted from element 11 to element 12, while orthogonally polarized light is reflected because it may be reused. In the meantime, the polarized light may change to a state transmitted by the element 11. In this example, the polarizer sheet 14 after the element 13 is a linear polarizing sheet. The linear polarizing sheet 14 is azimuthally rotated so that the polarization state of all pixels in the array remains unchanged and the display is dark because H is zero across the array of pixels when no current flows through the coil of the array. It may be arranged at an angle. Other configurations will be apparent to those skilled in the art. When a current flows through the coils of the array, the polarization state may change for each pixel, and thus an image such as a color image can be displayed. As described elsewhere in this specification, when the input polarization state of light to a magneto-optical SLM (MOSLM) is a pure linear polarization state, the current is passed through the coil so that the amplitude is encoded in the polarization state. Is possible. Such amplitude encoding enables a hologram with encoded amplitude information.

  In FIG. 1, a viewer located at a point 16 at a certain distance from a device including the hologram generator 15 may browse a three-dimensional image when viewing 15 directions. The elements 10, 11, 12, 13 and 14 may be arranged in physical contact, for example, in fact mechanical contact, each element being a single integral object in its entirety. One layer of the structure is formed to be The physical contact may be direct. Alternatively, physical contact may be indirect if there is a thin intermediate layer that is a film coating between adjacent layers. Physical contact may be limited to a small area that ensures proper mutual alignment or positioning, or may extend over a larger area, i.e., the entire surface of the layer. The physical contact can be done by bonding the layers together, such as by using a light transmissive adhesive to form the hologram generator 15, or any other suitable process (titled manufacturing process overview). (See further section below). However, if miniaturization is not particularly required for the device 15, some or all of the elements 10, 11, 12, 13, and 14 may be separated.

FIG. 4 is a prior art side view showing the three focusing elements 1101, 1102, 1103 of the vertical focusing system 1104 in the form of horizontally aligned cylindrical lenses in an array. Illustrated is a beam substantially parallel to a horizontal linear light source LS2 that passes through the focusing element 1102 of the illumination unit and reaches the observer plane OP. According to FIG. 4, many line light sources LS ₁ , LS ₂ , LS ₃ are arranged one above the other. Each light source emits light that is sufficiently coherent in the vertical direction and incoherent in the horizontal direction. The light passes through the transmission cell of the light modulator SLM. The light is diffracted only in the vertical direction by the cell of the light modulator SLM encoded with the hologram. The focusing element 1102 images the light source LS ₂ at some diffraction order (only 1 is practical) in the observer plane OP. Illustrated is that the beam emitted by the light source LS ₂ passes only through the focusing element 1102 of the focusing system 1104. In FIG. 4, the three beams indicate a first diffraction order 1105, a zeroth order 1106, and a minus first order 1107. In contrast to a single point light source, a linear light source can generate higher light intensity. Using several holographic regions that already have increased efficiency and / or line source assignments for each part of the 3D scene to be reconstructed improves the effective luminous intensity. Another advantage is that instead of a laser, many standard light sources positioned behind a slot bulkhead, which may be part of a shutter, for example, generate sufficiently coherent light.

  Applicant's preferred method for holographic encoding using a virtual observer window is, for example, US Pat. No. 6,057,054 filed by the applicant describing a device that reconstructs a three-dimensional scene by diffraction of sufficiently coherent light. Described in. However, as will be apparent to those skilled in the art, the holographic display of this implementation is not limited to such a method and includes all known holographic display types that may be used with MOSLM. Should be understood.

B. Holographic display device comprising two magneto-optical SLMs in series This implementation relates to a spatial light modulator (SLM) for complex modulation of light, ie independent amplitude and phase modulation. In particular, this implementation relates to an SLM based on the modulation of light by the Faraday effect. The SLM may be used in a holographic display. The holographic display may be used in a television, monitor, laptop computer, mobile phone, PDA, digital music player or any other device where a display is commonly used.

  This implementation provides a holographic display device that includes two magneto-optical SLMs in series. The combination can generate a three-dimensional image under appropriate lighting conditions. The display may be illuminated by multiple light sources or a single light source.

  This implementation relates to two MOSLMs for light modulation. Each MOSLM modulates amplitude, phase, or a combination of amplitude and phase. In particular, each MOSLM modulates light using the Faraday effect. The combined two MOSLMs may be used in a holographic display. A complex number composed of amplitude and phase is encoded for each pixel in transmitted light.

  A holographic display device composed of one or more light sources and two MOSLMs in series is used to modulate the amplitude and phase of light in a small and sequential manner as needed. This example of this implementation includes a first MOSLM and a second MOSLM. The first MOSLM modulates the amplitude of the transmitted light, and the second MOSLM modulates the phase of the transmitted light. Alternatively, the first MOSLM modulates the phase of the transmitted light, and the second MOSLM modulates the amplitude of the transmitted light. Alternatively, each MOSLM modulates the combination of amplitude and phase so that the two combined MOSLMs facilitate full complex modulation. Each MOSLM may be as described in Section A above. The entire assembly may be as described in section A, except that two MOSLMs are used.

  In the first step, a phase modulation pattern is written in the first MOSLM. In the second step, an amplitude modulation pattern is written in the second MOSLM. The light transmitted by the second MOSLM is modulated with respect to amplitude and phase so that the observer may observe a three-dimensional image when viewing the light emitted by the device in which the two MOSLMs are stored.

  Those skilled in the art will appreciate that phase and amplitude modulation facilitates the representation of complex numbers. Thus, this implementation may be used to generate a hologram so that a 3D image may be viewed by a viewer.

  An example implementation is described in FIG. 20 is an illuminating device for providing illumination of a planar area, and the illumination has sufficient coherence so that it can result in the generation of a 3D image. An example is described in US 2006/250671 for the case of wide area video holograms. An apparatus such as 20 is a cold cathode fluorescent lamp or white light emitting device that emits light in a focusing system that can be miniaturized, such as a lenticular array or a microlens array such as a cold cathode fluorescent lamp or a white light emitting diode. It may take the form of an array of white light sources such as diodes. Alternatively, the light source for 20 may include a red-green-blue laser or a red-green-blue light emitting diode that emits sufficiently coherent light. However, non-laser light sources (eg, light emitting diodes, OLEDs, cold cathode fluorescent lamps) with sufficient spatial coherence are more desirable than laser light sources. Laser light sources cause laser speckle in holographic light sources, are relatively expensive, and may damage the eyes of holographic display observers and the people who install holographic display devices. There is a disadvantage that there may be a safety problem.

  Element 20 may include one or two prismatic optical films to increase the brightness of the display. Such films are disclosed, for example, in US Pat. No. 5,056,892 and US Pat. No. 5,919,551, although other films are well known.

  The hologram generator 25 has a size range from a 1 cm diagonal screen size (or smaller) such as a mobile phone sub-display to a 1 m diagonal screen (or larger) large indoor display. Also good. Accordingly, the elements 20 to 23 and 26 to 28 may have a total thickness from 1 mm or less to several tens of cm or more in the case of a large indoor display. The element 21 is a polarizing optical element or a set of polarizing optical elements. An example is a linear polarizer sheet. A further example is a reflective polarizer that transmits one linear polarization state and reflects an orthogonal linear polarization state. Such sheets are described, for example, in US Pat. No. 5,828,488, but other sheets are well known. A further example is a reflective polarizer that transmits one circular polarization state and reflects an orthogonal circular polarization state. Such sheets are described, for example, in US Pat. No. 6,181,395, but other sheets are well known. The color filter may not be required when a color light source is used, but the element 22 is a color filter so that colored light pixels such as red light, green light, and blue light are emitted toward the element 23. It may be composed of an array. Element 23 is a MOSLM. In its simplest form, element 23 is an array of coils of conductive material, each coil being used to individually control the magnetic field due to the action of light through the corresponding pixel of the display. As described by equation (1), such that light passes through a medium having an effective Verde constant V so that linearly polarized light may be subjected to an effective rotation α as it passes through the medium. Control becomes easy. The medium may be in the form of a doped glass fiber cylinder or similar shape, as described in US Patent Application Publication No. 2005/0201705, which is incorporated herein by reference. Alternatively, the medium may be in the form of a magneto-optical film or magneto-photonic crystal as described in WO 2005/122479 A2, which is incorporated herein by reference.

  The element 26 is a polarizing optical element or a set of polarizing optical elements. Element 27 is a MOSLM as described above for element 23. The light emitted from the MOSLM passes through a polarization layer 28 such as a linear polarizer sheet. For transmitted light, element 23 modulates amplitude and element 27 modulates phase. Alternatively, element 27 modulates amplitude and element 23 modulates phase. This is considered preferable because the phase is expected to be more accurately modulated (i.e., noise is reduced proportionally) and the amplitude is at a maximum. The proximity of the MOSLMs 23 and 27 alleviates the problem of pixel crosstalk and optical loss caused by the divergence of the light beam. The closer the MOSLMs 23 and 27 are, the better approximation is achieved for non-overlapping propagation of the beam of colored light passing through the MOSLM.

  A viewer located at a point 24 at a certain distance from the device including the small hologram generator 25 may view a three-dimensional image when viewing the 25 directions. The elements 20, 21, 22, 23, 26, 27 and 28 may be arranged so that adjacent elements are in physical contact, eg, mechanically fixed and in contact with each other. Form one layer of the structure such that is a single monolithic object. The physical contact may be direct. Alternatively, physical contact may be indirect if there is a thin intermediate layer that is a film coating between adjacent layers. Physical contact may be limited to a small area that ensures proper mutual alignment or positioning, or may extend over a larger area, i.e., the entire surface of the layer. The physical contact can be done by bonding the layers together, such as using a light transmissive adhesive to form a small hologram generator 25, or any other suitable process (referred to as an overview of the manufacturing process). (See further section below). However, if miniaturization is not particularly required, some or all of the elements 20, 21, 22, 23, 26, 27, and 28 may be separated.

  Here we give a simple mathematical treatment of two MOSLMs in series that encode the SLM as a function of the current of the two coils per pixel. Further strict processing may be possible. The first Faraday rotator that modulates the phase, the first linear polarizer, the second Faraday rotator that modulates the amplitude, and the second linear polarizer are considered for their calculation in this order.

The first coil has a length L ₁ , a current I ₁ and a number of turns N ₁ . Therefore, the magnetic field generated by this coil along the axis is H1 = N ₁ I ₁ / L ₁ . The second coil has a length L ₂ , a current I ₂ and a number of turns N ₂ . Therefore, the magnetic field generated by this coil along the axis is H ₂ = N ₂ I ₂ / L ₂ . These equations are taken from P. Lorrain and D. Corson (WH Freeman and Co, San Francisco, USA, 1970) "Electromagnetic Fields and Waves", 2nd edition, pages 315-318.

The input light has circular polarization whose complex amplitude is expressed in Jones calculus as follows:
Due to the Faraday effect in the first rotator, the phase of this circularly polarized component is shifted by the amount represented by the following equation as described by equation (1):
α ₁ = V ₁ L ₁ H ₁ = V ₁ N ₁ I ₁
The amplitude after the Faraday rotator is:
The amplitude after the first linear polarizer is as follows:
To calculate the polarization rotation by the second Faraday rotator, the linearly polarized light is decomposed into a left circular polarization state and a right circular polarization state, which are phases shifted by α ₂ and −α ₂ respectively:
α ₂ = V ₂ L ₂ H ₂ = V ₂ N ₂ I ₂
The amplitude after the second Faraday rotator is:
Finally, the amplitude after the second linear polarizer is as follows:
The two MOSLMs modulate the amplitude by | cos (α ₂ ) | and modulate the phase by α ₁ .

Therefore, since the amount of phase α ₁ and amplitude factor | cos (α ₂ ) | of each pixel is equal to V ₁ B ₁ I ₁ and | cos (V ₂ N ₂ I ₂ ) |, respectively, the coil current I ₁ and I ₂ is used to control them.

  Here, a specific example of an implementation is given. Two MOSLMs are combined in series. Each layer includes modulated pixels that are controlled by a coil and are individually addressed. The layers are aligned so that the light modulated at the pixels of the first layer is then modulated by the corresponding pixels of the second layer. The modulation characteristics of each layer are such that two layers operating in series facilitate complex modulation of light, ie amplitude and phase. Optionally, the SLM may include an array of controllable prism elements that facilitate beam steering. Optionally, the SLM may include an embedded computer.

  FIG. 5 is a cross-sectional view of such an SLM including:

The two layers 53, 54, 56, 57 of the magneto-optical modulator
・ Prism element 59 for beam steering
A computer built into the SLM for the calculation of holograms and the control of modulators and prism elements. This may be referred to as a display (CIAD) 52 computer. Circuitry for such a computer may be grown on a glass substrate, as described in the applicant's UK Patent Application Publication No. 07093766.8 and UK Patent Application Publication No. 07099379.2. The actual device has more pixels than the three pixels shown in FIG. For example, an actual device may have an array of 1,000 × 1,000 pixels that gives 1 million pixels.

  The device shown in FIG. 5 includes three pixels 511, 512 and 513 and one prism element 59. It is understood that the implementations are not limited to their number and their ratio 3: 1.

  The SLM shown in FIG. 5 includes several layers having:

-Bottom glass substrate 51
・ Computer CIAD52
A first layer having a coil 53 in which a cross-sectional view of three coils is shown a first magnetic photonic crystal layer 54
First polarizer 55
Second magnetic photonic crystal layer 56
A second layer having a coil 57 in which a cross-sectional view of three coils is shown a second polarizer 58
・ Prism element 59 for beam steering
-Upper glass substrate 510
Three pixels 511, 512, and 513 are shown in FIG. As indicated by broken lines, each pixel stack extends from the first layer of coil 53 to the second polarizer 58. The SLM will be described with respect to the pixel 511. The direction of light propagation is from the bottom glass substrate 51 to the top glass substrate 510.

  The coil 514 generates a magnetic field and controls the modulation of light in the first magnetic photonic crystal layer (MPC) 54. The light passes through the first polarizer 55 and is then modulated by the second MPC 56 controlled by the second coil 516. The second polarizer 58 is at the output of the pixel 511. Each MPC consists of a multilayer structure of magneto-optical layers that greatly increases the Verde constant. The MPC multi-layer structure will be described in “A Presentation for Investors” by Panorama Labs of Rockefeller Center, 1230 Avenue of the Americas, 7th Floor, New York, NY 10020 USA (www.panoramalabs.com) obtained from the Internet. .

  Two MPCs 54, 56 are used to modulate the phase and amplitude of the light passing through each pixel. As an example, the light entering the pixel 511 is in a left circularly polarized state. After passing through MPC 54, the light is still left circularly polarized and has a phase shift j1 that depends on the magnetic field generated by coil 514. The polarizer 55 transmits left circularly polarized light to linearly polarized light having a constant amplitude and a phase shift j1. This light is modulated in the MPC 56. Thereafter, the polarization is still linear, but the direction of polarization is rotated by an angle α that depends on the magnetic field generated by the coil 516. After the second linear polarizer 58, the light has a constant polarization direction and an amplitude that depends on the rotation angle α.

  The above is an example of a method for modulating the phase and amplitude of light in a pixel by two MPCs. It will be appreciated that other combinations of modulation characteristics, input / output polarization and polarizer orientation are possible, as will be apparent to those skilled in the art. There may be mixed amplitude and phase modulation at each MPC. In the case of full complex modulation, the combined modulation in MPC 54 and MPC 56 facilitates controllable complex modulation of amplitudes from zero to maximum amplitude values and phases from 0 to 2π radians.

  An optional layer that includes prism element 59 includes electrodes 517, 518 and a cavity filled with two separate liquids 519, 520. Each liquid fills the prismatic portion of the cavity. As an example, the liquid may be oil and water. The inclination of the interface between the liquids 519 and 520 depends on the voltage applied to the electrodes 517 and 518. If the liquid has a different refractive index, the light beam experiences a deviation that depends on the voltage applied to the electrodes 517,518. Accordingly, the prism element 59 operates as a controllable beam steering element. This is an important feature of Applicant's preferred method for electronic holography requiring VOW tracking to the observer's eye. In German Patent Application Publication No. 102007024237.0 and German Patent Application Publication No. 102007024236.2 filed by the present applicant, the tracking of VOW for the observer's eye by a prism element is described.

  The optional CIAD 52 is used to calculate holograms, control pixel coil currents, and control prism elements. Examples of CIAD implementations for holographic displays are described in British Patent Application Publication No. 0709376.8 and British Patent Application Publication No. 07099372 filed by the present applicant.

  The CIAD 52 of FIG. 5 is attached directly to the bottom glass substrate and is made using thin film transistor (TFT) technology. Control signals to the coil and prism elements are transmitted via feedthroughs or conductive contacts as indicated by label 515 in FIG. This is just an example. Other locations of CIAD are possible, for example:

• Two CIADs, one on the bottom substrate and the other on the top substrate. Synchronization is externally provided through the through connection or by the synchronization operation of the two CIADs.
-Two CIADs, one on each side of the polarizer 55. This ensures that the distance to the coil is short.
One or two CIADs on one or both sides of a flexible sheet that is attached to a glass substrate, MPC, coil or polarizer.

It is understood that the implementation is not limited to this list of CIAD locations.
There are several possibilities for through connections or contacts between the CIAD, the coil and the electrodes of the prism element or between multiple CIADs. For example, it is as follows.
Etching or drilling of holes, or manufacturing of holes by photolithography and filling with conductive material.
Adhesion of the connection area of one layer to the connection area of the other layer with a conductive adhesive.
-Manufacture of composite multilayer sheets that may include one or more CIADs, polarizers or coils.

It will be appreciated that implementations are not limited to this list of possibilities.
Care must be taken to avoid or compensate for crosstalk between magnetic fields.
Crosstalk between the magnetic fields (stray magnetic fields) of the first coil 514 and the second coil 516 that cause errors in light modulation is calculated and compensated. Calculations and compensation can be done in real time or using a look-up table (LUT).
• Since the stray field away from the axis of the coil is small, usually crosstalk between adjacent pixels may be ignored. If not ignored, crosstalk may be calculated or compensated online or using an LUT.
• Crosstalk of the stray field of CIAD to MPC (and MPC to CIAD) is minimized by careful layout design. As an example, circuit paths containing equal currents in opposite directions are positioned close together so that the far-field magnetic field cancels and is a good approximation.

  Light crosstalk from one pixel to an adjacent pixel is avoided by a short optical path from 53 to 58 in the pixel (ie, in a direction perpendicular to 51 toward 510 in FIG. 5). This reduces the amount of diffracted light to adjacent pixels to a value that can be ignored.

The polarizers 55 and 58 should also be thin layers. Examples include:
・ Polymer sheet polarizer.
A layer containing small embedded metal particles that absorb one polarization direction.
A wire grid polarizer composed of an array of parallel nanostructured wires that transmit light in one polarization direction and reflect the other (eg, Moxtek Inc. of 452 West 1260 North, Orem, UT 84057, USA Manufactured by).

  The entire SLM may be a small SLM with a diagonal of about a few centimeters, such as an SLM that may be used as a sub-display for a mobile phone, or an SLM for use in a projection display where the SLM is optically expanded. A small SLM with a diagonal of 1 cm or less may be used. Alternatively, the SLM may be a large SLM having a diagonal of up to about 1 meter or more for use in a direct view display that is viewed in full size by several observers. SLM diagonal sizes between small and large sizes are feasible for various applications.

The SLM described in the above example has the following characteristics.
Two MPCs for independent amplitude and phase modulation
・ Prism element for beam steering ・ Hilogram calculation and CIAD for coil and prism element control
Less complex SLMs can also be produced.
SLMs without prism elements can be used in combination with external beam steering elements such as light source tracking, scanning mirrors or external prism elements.
An SLM without a CIAD can be used with an external computer for hologram calculation and coil and prism element control.
• If the user manually points the device to place the VOW at the eye position, an SLM without eye tracking can be used in a handheld device.

  The disclosed SLM is preferably used for holographic displays that are projection holographic displays or direct view holographic displays. SLMs that include built-in prism elements for beam steering are suitable for holographic displays based on Applicants' preferred method for holographic displays using tracked VOWs.

  Applicant's preferred method for holographic encoding using a virtual observer window is, for example, a patent document filed by the applicant describing a device that reconstructs a three-dimensional scene by diffraction of sufficiently coherent light. 1. However, as will be apparent to those skilled in the art, the holographic display of this implementation is not limited to such a method, and all well known that may be used with a pair of MOSLMs to perform complex holographic encoding. It should be understood that this includes the types of holographic displays.

C. A small combination of MOSLM and small light source This implementation provides a small combination of MOSLM and small light source with sufficient coherence. The combination can generate a three-dimensional image under appropriate lighting conditions.

  In this example, a small combination of MOSLM and a small light source that does not require an imaging optical device will be described. This implementation provides a small combination of one or more light sources, focusing means, MOSLM and light beam splitter elements, which combination can generate a three-dimensional image under suitable illumination conditions. “No need for an imaging optical device” means that there is no focusing means, unlike means for focusing one or more light sources, for example, typically a microlens array.

  In FIG. 11, an implementation example is described. 110 is an illuminating device for providing illumination of a planar area, the illumination having sufficient coherence to result in the generation of a three-dimensional image. As an example of the illumination device, US Pat. No. 5,153,670 discloses an example reproduced in FIG. 4 in the case of a wide-area video hologram. A device such as 110 takes the form of an array of white light sources such as cold cathode fluorescent lamps or white light emitting diodes that emit incident light in a compact focusing system, such as a lenticular array or a microlens array. Good. Alternatively, the light source for 110 may include a red-green-blue laser or a red-green-blue light emitting diode that emits sufficiently coherent light. The red, green and blue light emitting diode may be an organic light emitting diode (OLED). However, non-laser light sources (eg, light emitting diodes, OLEDs, cold cathode fluorescent lamps) with sufficient spatial coherence are more desirable than laser light sources. Laser light sources cause laser speckle in holographic light sources, are relatively expensive, and may damage the eyes of holographic display observers and the people who install holographic display devices. There is a disadvantage that there may be a safety problem.

  Element 110 may include one or two prismatic optical films to increase the brightness of the display. Such films are disclosed, for example, in US Pat. No. 5,056,892 and US Pat. No. 5,919,551, although other films are well known.

  The thickness of element 110 may be about a few centimeters or less. In a preferred implementation, the elements 110-113, 116 have a total thickness of less than 3 cm to provide a compact light source with sufficient coherence. The color filter may not be required when a color light source is used, but the element 111 is a color filter so that colored light pixels such as red light, green light, and blue light are emitted toward the element 112. It may be composed of an array. The element 112 is a polarizing element or a collection of polarizing elements. Element 113 is a MOSLM. The element 116 is a polarizing element or a collection of polarizing elements. An optical beam splitter element may follow element 116. A viewer located at a point 114 at a distance from a device that includes a small hologram generator 115 may view a three-dimensional image when viewing the direction of 115.

  As will be apparent to those skilled in the art, the optical components described in Section A may be included in the miniature hologram generator 115.

  A MOSLM is an SLM in which each cell of an array of cells may be electrically addressed to modulate the polarization state of polarized light by the Faraday effect. Each cell has some effect on incident light, for example, to modulate the amplitude of transmitted light, to modulate the phase of transmitted light, or to modulate the combination of transmitted light amplitude and phase. An example of a MOSLM is given in US Pat.

  Elements 110, 111, 112, 113, and 116 each have a layer of structure that allows adjacent elements to be physically (eg, actually mechanical, touching, and all in one, single object). To be formed). The physical contact may be direct. Alternatively, it may be indirect as long as there is a thin intermediate layer covered with a film between adjacent layers. The physical contact may be limited to a small area to ensure mutual coordination and registration, or may be spread over a wide area or the entire surface of the layer. The physical contact is affixed together by the use of an optically conductive adhesive to form the miniature hologram generator 115 or by other suitable processing (see the section titled “Manufacturing Process Overview” below). It may be made by a layer formed.

FIG. 4 is a prior art side view showing the three aggregation elements 1101, 1102, 1103 of the vertical focusing system 1104 in the form of horizontally aligned cylindrical lenses in an array. Illustrated is a beam substantially parallel to a horizontal linear light source LS2 that passes through the focusing element 1102 of the illumination unit and reaches the observer plane OP. According to FIG. 4, many line light sources LS ₁ , LS ₂ , LS ₃ are arranged one above the other. Each light source emits light that is sufficiently coherent in the vertical direction and incoherent in the horizontal direction. The light passes through the transmission cell of the light modulator SLM. The light is diffracted only in the vertical direction by the cell of the light modulator SLM encoded with the hologram. The focusing element 1102 images the light source LS ₂ at some diffraction order (only 1 is practical) in the observer plane OP. Illustrated is that the beam emitted by the light source LS ₂ passes only through the focusing element 1102 of the focusing system 1104. In FIG. 4, the three beams indicate a first diffraction order 1105, a zeroth order 1106, and a minus first order 1107. In contrast to a single point light source, a linear light source easily allows for a product with a higher intensity. Using several holographic regions that already have increased efficiency and / or line source assignments for each part of the 3D scene to be reconstructed improves the effective luminous intensity. Another advantage is that instead of a laser, many standard light sources positioned behind a slot bulkhead, which can be part of a shutter, for example, generate sufficiently coherent light.

  In general, holographic displays reconstruct the wavefront in a virtual observer window. The wavefront, if present, is what the real object would have created. The observer sees the reconstructed object when his eye is located in one of the several valid virtual observer windows (VOWs). As shown in FIG. 6A, the holographic display includes components such as a light source, a lens, an SLM, and an optical beam splitter.

  To facilitate the creation of a small combination of an SLM displaying a holographic image and a small light source, the single light source and single lens of FIG. 6A, as shown in FIG. A light source array and a single lens array or a lenticular array may be respectively replaced. In FIG. 6B, the light source illuminates the SLM and the lens projects the light source onto the viewer plane. The SLM encodes the hologram and modulates the incident wavefront so that the desired wavefront can be reconstructed in the VOW. The optical beam splitter element may be used to generate several VOWs, for example, a VOW for one left eye and a VOW for one right eye.

  If a light source array, lens array, or lenticular array is used, the light source from the array is placed so that the light beam passes through all of the lens array or lenticular array with the matching VOW. Should.

  The device of FIG. 6B is useful for small designs that can be used in small holographic displays. The holographic display described above may be used in a mobile device such as a mobile phone or a PDA. In general, the holographic display has a screen diagonal on the order of one inch or several inches. Suitable components are described in detail below.

1) Light source / light source array In a simple case, a fixed single light source can be used. If the viewer moves, the viewer will be tracked and the display will be adjusted to produce an observable image at the viewer's new location. Here, there is no VOW tracking, or tracking will be performed using the beam steering element behind the SLM.

  A configurable light source array may be achieved by a MOSLM illuminated by a backlight. Only the appropriate pixels are switched to the transmissive state to produce an array of points or line sources. The maximum switching speed of such an array would be much faster than in other SLMs that utilize LC or MEMS technology. These light source apertures must be small enough to ensure sufficient spatial coherence for holographic reconstruction of the object. An array of point light sources may be used in combination with a lens array including a 2D array of lenses. The array of line light sources may be used in combination with a lenticular array that includes a parallel array of cylindrical lenses.

  Preferably, the OLED display is used as a light source array. When an OLED display is used as a light source array, only those pixels are switched so that they are needed to generate a VOW at the eye position. The OLED display may have a 2D array of pixels or a 1D array of line light sources. The illumination area of each point source or the width of each line source should be small enough to ensure sufficient spatial coherence for holographic reconstruction of the object. Furthermore, the array of point light sources is preferably used in combination with a lens array having a 2D array of lenses. The array of line light sources is preferably used in combination with a lenticular array having a parallel array of cylindrical lenses.

2) Focusing means: single lens, lens array, or lenticular array The focusing means images a single or a plurality of light sources on the observer plane. Since the SLM is close to the focusing means, the Fourier transform of the information encoded in the SLM exists in the observer plane. The focusing means has one or a plurality of focusing elements. The positions of the SLM and the focusing means may be interchanged.

  For a small combination of a MOSLM and a small light source with sufficient coherence, it is essential to have a thin focusing means. Standard reflective lenses with convex surfaces are very thick. Instead, a diffractive lens or a holographic lens may be used. This diffractive lens or holographic lens may have the function of a single lens, a lens array, or a lenticular array. The above components may utilize surface relief holographic products provided by Physical Optics Corporation, Torrance, CA, USA. Alternatively, a lens array may be used. The lens array includes a 2D array of lenses, each lens being assigned to one light source of the light source array. Another alternative may be to use a lenticular array. The lenticular array has a 1D array of cylindrical lenses, each lens having a corresponding light source in the light source array. As described above, if a light source array, lens array, or lenticular array is used, the light source in the array will have a luminous flux that matches all the lenses in the lens array or the matching lenticular array in the VOW. Should be positioned through the array.

  Light that passes through a lens array, or a lens of a lenticular array, is incoherent to one lens associated with a plurality of other lenses. Therefore, the hologram encoded by the SLM is composed of sub-holograms, and each sub-hologram corresponds to one lens. The aperture of each lens should be large enough to ensure sufficient resolution of the reconstructed object. For example, as described in U.S. Patent Application Publication No. 2006/0055994, a lens having an aperture that is approximately the same size as the typical size of the encoded region of the hologram may be used. This means that each lens should have an aperture on the order of one or several millimeters.

3) SLM
The hologram is encoded with SLM. Usually, the encoding for a hologram consists of a complex 2D array. Thus, ideally, the SLM could modulate the amplitude and phase of the local light beam that passes through each pixel of the SLM. However, a typical SLM can modulate either amplitude or phase, but cannot modulate amplitude and phase independently.

  Amplitude modulation SLM may be used in combination with detour phase encoding, eg, Burckhardt encoding. The difficulty is that 3 pixels are required to encode one complex number and the reconstructed object has low brightness.

  The reconstruction result of the phase modulation SLM is high brightness. For example, so-called two-phase encoding may be used that requires two pixels to encode one complex number.

  MOSLM has well-defined edge characteristics, which can lead to unwanted higher-order diffraction orders in the diffraction pattern, but this problem can be reduced or eliminated by using a soft aperture. can do. A soft aperture is an aperture without a sharp transmission cut-off. An example of a soft aperture transmission function has a Gaussian profile. Gaussian profiles are known to be advantageous in diffractive systems. This is because there exists a mathematical result that the Fourier transform of the Gaussian function is itself a Gaussian function. Therefore, the beam intensity profile function is not changed by diffraction except for the lateral scaling parameter, as compared with the case of transmitting through an aperture having a sharp cutoff in the transmission profile. A sheet array of Gaussian transmission profiles may be provided. When provided in line with the MOSLM aperture, a system is provided that lacks or is significantly reduced in higher diffraction orders compared to a system with a sharp cutoff in the beam transmission profile. The

4) Beam splitter element VOW is limited to one periodic interval of the Fourier transform of the information encoded in the SLM. According to the SLM with the highest resolution currently available, the VOW size is on the order of 10 mm. In some situations, this may be too small for holographic display applications without tracking. One solution to this problem is to spatially multiplex VOWs, generating more than one VOW. When performing spatial multiplexing, VOWs are generated simultaneously from different locations on the SLM. This may be realized by a beam splitter. For example, a pixel group with an SLM is encoded with VOW1 information, and other groups are encoded with VOW2 information. The beam splitter separates light from these two groups so that VOW1 and VOW2 are parallel in the viewing plane. A larger VOW may be generated by seamlessly tiling VOW1 and VOW2. Multiplexing may also be used to generate left eye and right eye VOWs. In that case, seamless parallelization is not required and a gap may occur between one or several VOWs for the left eye and one or several VOWs for the right eye. Here, care must be taken so that the higher order diffraction orders of one VOW do not overlap with the higher order diffraction orders of other VOWs.

  A simple example of a beam splitter element is a black with transparent areas between the stripes, as described in U.S. Patent Application Publication No. 2004/223049, which is incorporated herein by reference. It is a parallax barrier made of a striped pattern. A further example is a lenticular sheet, as described in U.S. Patent Application Publication No. 2004/223049. Further examples of beam splitter elements are lens arrays and prism masks. Small holographic displays are not satisfactory for a typical observer with two eyes about 10 cm apart, but the typical virtual observer window size of 10 mm is large enough with only one eye Thus, typically the presence of a beam splitter element would be expected. However, time multiplexing may be used instead of spatial multiplexing. Time multiplexing can be realized by using MOSLM. This is because MOSLM has a very high speed switching function as described above. If no spatial multiplexing is performed, it is not necessary to use a beam splitter element.

  Spatial multiplexing may be utilized for color holographic reconstruction. For spatial color multiplexing, there are independent pixel groups for red, green and blue color components. These groups are spatially separated on the SLM and are illuminated simultaneously with red light, green light and blue light. Each group is encoded with a hologram calculated for each color component of the object. Each group reconstructs the color components of the holographic object reconstruction.

5) Time multiplexing When time multiplexing is performed, VOWs are continuously generated from the same position of the SLM. This may be achieved by changing the position of the light source and re-encoding in sync with it. The light source position must be changed so that the VOWs are seamlessly parallelized on the observation surface. If time multiplexing is fast enough, i.e. greater than 25 Hz for the entire cycle, the human eye will see a continuous extended VOW.

  Multiplexing may be utilized for the generation of left eye and right eye VOWs. In that case, seamless parallelization is not necessary, and there may be a gap between one or several VOWs for the left eye and one or several VOWs for the right eye. This multiplexing may be spatial or temporal.

  Spatial multiplexing and time multiplexing may be combined. For example, in order to generate an extended VOW for one eye, three VOWs are spatially multiplexed. This extended VOW is time-multiplexed to generate an extended VOW for the left eye and an extended VOW for the right eye.

  Care must be taken so that the higher diffraction orders of one VOW and the other VOW do not overlap.

  Multiplexing for VOW extension is preferably used in conjunction with SLM re-encoding, as it provides an extended VOW whose parallax changes continuously in response to observer behavior. For simplicity, multiplexing without re-encoding will provide repetitive content in different parts of the extended VOW.

  Time multiplexing may also be utilized for the generation of color holographic reconstructions. Due to time multiplexing, the three color component holograms are sequentially encoded on the SLM. The three light sources are switched in synchronism with re-encoding on the SLM. If the entire cycle is repeated fast enough, ie greater than 25 Hz, it will appear to the human eye as a continuous color reconstruction.

  Time multiplexing can be realized by using MOSLM. This is because MOSLM has a very high speed switching function as described above.

6) Eye Tracking
In a small combination of MOSLM and a small light source that is sufficiently aligned with eye tracking, the eye position of the observer may be detected by an eye position detector. One or more VOWs are automatically placed at the eye position to allow the observer to see the reconstructed object through the VOW.

  However, tracking is not always practical, especially in the case of portable devices. This is because there are constraints based on the requirements of additional devices and power requirements for execution. Without tracking, the observer must manually adjust the position of the display. In a preferred implementation, this is done immediately because the small display is a handheld display such as that incorporated in a PDA or mobile phone. PDA and mobile phone users tend to see the display from a direction orthogonal to the display, so that little additional effort is needed to adjust the VOW to the eye. For example, as described in WO 01/96941, which is incorporated herein by reference, a user of a handheld device can manually position the device in the right direction to achieve optimal viewing conditions. It is known that there is a tendency to turn automatically. Therefore, such a device does not require tracking of the user's line of sight, and does not require a complicated and small tracking optical element such as a scanning mirror. However, line of sight tracking may be implemented in such a device if the additional requirements and power on the device do not place an excessive burden on the device.

  Without tracking, the small combination of MOSLM and a small enough light source that is sufficiently coherent requires the VOW to be large enough to simplify the adjustment of the display. Desirably, the VOW size should be several times the size of the human eye. This can be realized either by a single large VOW using an SLM with a small pitch or by arranging several small VOWs using a SLM with a large pitch in a tile shape.

  The position of the VOW is determined by the position of the light source in the light source array. The eye position detector detects the position of the eye and sets the position of the light source in order to adjust the VOW to the position of the eye. This type of tracking is described in US 2006/055944 and US 2006/250671.

  When the light source is at a fixed position, the VOW may be moved. Light source tracking requires an SLM that is relatively insensitive to fluctuations in the incident angle of light from the light source. If the VOW position is moved by moving the light source, the small light source and the SLM have a small combination because the deviation from the light propagation conditions in the small combination suggested by such a configuration is It becomes difficult to achieve. In such a case, it is advantageous to have a constant optical path in the display.

7) Example An example will be described for a small combination of a MOSLM and a sufficiently coherent small light source. This combination makes it possible to generate a three-dimensional image under appropriate exposure conditions and may be mounted on a PDA or a mobile phone. A small combination of MOSLMs and a sufficiently coherent small light source has an OLED display as the light source array, MOSLM and lens array as shown in FIG.

  Depending on the required position of the VOW, a specific pixel of the OLED display is driven. These pixels irradiate MOSLM and form an image on the observation surface by the lens array. In the OLED display, at least one pixel is driven for each lens of the lens array. For the dimensions given in the drawing, for a pixel pitch of 20 μm, the VOW can be tracked with a horizontal increment of 400 μm. This tracking is quasi-continuous.

  OLED pixels are only partially spatially coherent light sources. Because it is partially coherent, there will be smear in the reconstruction of object points. For the dimensions given in the drawing, an object point having a distance of 100 mm from the display is reconstructed with a horizontal smear of 100 μm if the pixel width is 20 μm. This is sufficient as the resolution of the human vision system.

There is not enough mutual coherence between the light passing through different lenses of the lens array. The coherence requirement is limited to each single lens of the lens array. Therefore, the resolution of the reconstructed object point is determined by the pitch of the lens array. A typical lens pitch will be on the order of 1 mm to ensure sufficient resolution for a human vision system. If the OLED pitch is 20 μm, this means that the ratio of lens pitch to OLED pitch is 50: 1. If only a single OLED emits light per lens, this means that only one OLED emits every 50 ² = 2500 OLEDs. Thus, the display will be a low power display. The difference between the holographic display of the implementation and the conventional OLED is that the former concentrates the light in the viewer's eyes while the latter emits the light to 2π steradians. While conventional OLED displays have achieved 1000 cd / m ² , the inventors should in this embodiment the illuminated OLED should achieve a brightness several times 1000 cd / m ² for realistic applications And calculated.

  VOW is limited to one diffraction order of the Fourier spectrum of the information encoded in the SLM. If the pixel pitch of the MOSLM is 20 μm, the VOW has a width of 10 mm at a wavelength of 500 nm. The VOW may be expanded by arranging the VOW in a tile shape by spatial multiplexing or time multiplexing. In the case of spatial multiplexing, additional optical elements such as beam splitters are required.

  Color holographic reconstruction can be realized by time multiplexing. The red, green and blue pixels of a color OLED display are driven continuously with SLM synchronous re-encoding with holograms calculated for red, green and blue light wavelengths.

  The display may include an eye position detector that detects the position of the observer's eyes. The eye position detector is connected to a control unit that controls driving of the pixels of the OLED display.

  The calculation of SLM-encoded holograms is preferably performed in an external encoding unit since it requires high computational power. Display data is transmitted to a PDA or mobile phone in order to enable display of a holographically generated three-dimensional image.

D. Small combination of MOSLM sets In yet another embodiment, a combination of two MOSLMs can be used to modulate the amplitude and phase of light in sequence and in a small manner. As described above, the complex number composed of the amplitude and the phase can be encoded into the transmitted light for each pixel unit.

  This embodiment includes a small combination of two MOSLMs. The first MOSLM modulates the amplitude of the transmitted light, and the second MOSLM modulates the phase of the transmitted light. Alternatively, the first MOSLM modulates the phase of the transmitted light, and the second MOSLM modulates the amplitude of the transmitted light. This is considered desirable if the phase is expected to be more accurately modulated (i.e., relatively less noisy) when the amplitude is at its maximum value. Each MOSLM may be similar to that described in Section C above. The overall assembly may be similar to that described in Section C except for the two MOSLMs used here. Other combinations in the modulation characteristics of the two MOSLMs are possible, equivalents that facilitate independent amplitude and phase modulation.

  In the first step, the first MOSLM is encoded with a pattern for amplitude modulation. In the second step, the second MOSLM is encoded with a phase modulation pattern. The transmitted light is modulated with the amplitude and the phase by the second MOSLM, and as a result, the observer observes the three-dimensional image when viewing the light emitted by the device incorporating the two MOSLMs. be able to.

  It will be appreciated by those skilled in the art that phase and amplitude modulation facilitates the representation of complex numbers. Furthermore, the MOSLM can also have a high resolution. Therefore, this embodiment is used to generate a hologram such as a three-dimensional image observed by an observer.

  FIG. 13 shows an example of the embodiment. Reference numeral 130 denotes an illuminating device for providing illumination in a planar area. The illumination has sufficient coherence to lead to the generation of a 3D image. An example of a lighting device is disclosed in US patent application 2006/250671 for a wide-area video hologram case. An example of this is shown in FIG. A device such as 130 is a structure of an array of white light sources, such as cold cathode fluorescent lamps or white light emitting diodes that illuminate light that is incident on a small focusing system such as a lenticular array or microlens array. Can be taken. Alternatively, the light source at 130 may comprise a red, green, blue laser or a red, green, blue light emitting diode that emits light of sufficient coherence. The red, green and blue light emitting diodes may be organic light emitting diodes. However, non-laser light sources (eg, light emitting diodes, OLEDs, cold cathode fluorescent lamps) with sufficient spatial coherence are more desirable than laser light sources. Laser light sources cause laser speckle in holographic reconstruction, are relatively expensive, or damage the eyes of observers of holographic displays and those engaged in the assembly of holographic display devices There are disadvantages such as safety issues related to the possibility of giving

  Element 130 may be about a few centimeters or less in thickness. In a preferred embodiment, the elements 130-135 have a total thickness of less than 3 cm so as to provide a compact light source with sufficient coherence light. The element 131 may include an array of color filters such as pixels of colored light such as red, green, and blue light. However, if a colored light source of light is used, a color filter is not required. The element 132 is a polarizing element or a set of polarizing elements. The element 133 is a MOSLM. Element 134 is a MOSLM. Elements 133 and 134 each include a polarizing element or a set of polarizing elements. Element 135 is any optical beam splitter element. For transmitted light, element 133 modulates amplitude and element 134 modulates phase. Alternatively, element 134 modulates amplitude and element 133 modulates phase. The proximity of the MOSLMs 134, 133 allows for the reduction of pixel crosstalk problems resulting from optical loss and light beam divergence. When the MOSLMs 134, 133 are in close proximity, a better approximation of non-overlapping propagation of colored light beams through the MOSLM can be realized. An observer located at a point 135 at some distance from the device including the small hologram generator 136 can see a three-dimensional image when viewed in the 136 direction.

  The elements 130, 131, 132, 133, 134, and 135 are configured such that, for example, adjacent elements such as a fixing mechanism and a contact that form a structural layer such that the whole is a single unitary object are physically configured. Be placed. The physical contact may be direct. Alternatively, it may be indirect if there is a thin film, an intermediate layer, or a film coating between adjacent layers. The physical contact can be limited to a small area that guarantees mutual alignment or correction of registration, or can be extended to a large area or the entire surface of the layer. The physical contact can be by layers adhered to each other, such as through the use of luminescent adhesives to form a small hologram generator 136, or any other suitable process (in the outline of the manufacturing process below). (See also section).

  If the MOSLM performs amplitude modulation, in a normal configuration, the incident light beam will be linearly polarized as the beam passes through the linear polarizing sheet. Amplitude modulation is controlled by rotation of the linear polarization state in a magnetic field applied along the light propagation direction that affects the polarization state of the light through the Faraday effect. In such a device, when light from MOSLM passes through another linear polarizing sheet, it allows intensity reduction, resulting in some rotation in the polarization state of the light to pass through MOSLM.

  When the MOSLM performs phase modulation, in a normal configuration, the incident lead light beam will be circularly polarized by passing the beam through a linear polarizing sheet and a quarter wave plate. Phase modulation is controlled by the Faraday effect by applying a magnetic field that affects the polarization state of light along the direction of light propagation. A directional magnetic field is generated by the current flowing through the coil. In phase modulation, each pixel of the output beam has a phase difference with respect to the input beam that is a function of the current flowing in the coil corresponding to each pixel.

  A small assembly used in a small holographic display comprises two MOSLMs that are connected with a small or minimal separation. In the preferred embodiment, both SLMs have the same number of pixels. Since the two MOSLMs are not equidistant from the observer, the pixel pitch of the two MOSLMs has a slight difference (but the current situation is almost the same) to offset the effect of being at different distances to the observer. Necessary. The light that has passed through the pixels of the first SLM passes through the corresponding pixels of the second SLM. Thus, light is modulated by both SLMs, and complex amplitude and phase modulation is achieved independently. As an example, the first SLM is amplitude modulation and the second SLM is phase modulation. Also, any other combination of modulation characteristics in the two SLMs may facilitate independent modulation of amplitude and phase with each other.

  Care must be taken that light passing through the pixels of the first SLM passes only through the corresponding pixels of the second SLM. Crosstalk will occur if light from the first SLM pixel passes through non-corresponding pixels and neighboring pixels of the second SLM. The crosstalk may cause a reduction in image quality. Here are described four possible approaches to the problem of minimizing crosstalk between pixels. It will be apparent to those skilled in the art that these approaches may be applied to the embodiments in Section B.

  (1) The first and simplest approach is to directly connect or glue two SLMs with aligned pixels to each other. There will be diffraction at the pixels of the first SLM that causes a branch of light propagation. The separation between the SLMs must be thin enough to maintain crosstalk between adjacent pixels of the second SLM at an acceptable level. As an example, for a pixel pitch of 10 μm, the separation part of the two MOSLMs needs to be on the order of 10 to 100 μm or less. This is almost impossible to achieve with conventional manufactured SLMs, where the cover glass thickness is of the order of 1 mm. On the contrary, it is more desirable that the sandwich structure be manufactured in one process with only a thin separation layer between the SLMs. The manufacturing approach outlined in the manufacturing process overview section can be applied to manufacture devices that include two MOSLMs separated by a short or minimal distance.

  FIG. 14 is a two-dimensional model showing diffraction from a 10 μm wide slit and calculated Fresnel diffraction profiles at various distances from the slit. Here, the vertical axis indicates the slit (z), and the horizontal axis indicates the slit (x). A similar illumination slit is located between −5 μm and +5 μm on the x-axis with z equal to 0 microns. The transmission medium has a refractive index of 1.5. This can be representative of media that would be used in a small device. The light is taken as red light at a vacuum wavelength of 633 nm. The wavelengths of green light and blue light have shorter wavelengths than red light, so that calculations on red light exhibiting the shortest diffraction will affect the three colors, red, green and blue. The calculations are performed using Mathcard® software sold by Parametric Technology® Corp. of Needham, Massachusetts, USA. FIG. 15 shows a part of the intensity within a width of 10 μm with the center of the slit as the center, like a distance function from the slit. At a distance of 20 μm from the slit, as shown in FIG. 15, there is still an intensity of over 90% within the 10 μm width of the slit. Thus, less than about 5% of the pixel intensity will be incident on each adjacent pixel in this two-dimensional model. This calculation limits the space between pixels as a zero boundary width. The actual boundary width between pixels is greater than zero. Thus, in a real system, the crosstalk problem will be smaller than the value calculated here. In FIG. 14, a Fresnel diffraction profile close to a slit such as 50 μm from the slit is somewhat approximated to the highest intensity function at the slit. Therefore, there is no wide-range diffraction characteristic close to the slit. A wide range of diffraction properties is characteristic of the topmost far-field diffraction function. This is a sinc square function known to those skilled in the art. A wide range of diffraction characteristics can be seen in the case of a distance of 300 μm from the slit of FIG. This indicates that the diffraction effect is controlled by placing two MOSLMs close enough. The benefit of placing two MOSLMs in close proximity is that the functional form of the diffraction profile is changed from a far-field feature to a more effective functional form that includes light close to the axis perpendicular to the slit. This benefit counters those skilled in the art of holography so that those skilled in the art tend to expect powerful, effective, and unavoidable diffraction effects as light passes through the small aperture of the SLM. One. Therefore, those skilled in the art are not willing to place two SLMs in close proximity to each other, as one skilled in the art expects that due to diffraction effects will result in an inevitable and serious problem with pixel crosstalk. Will.

  FIG. 16 shows a contour plot of the intensity distribution as a function of distance from the slit. Contour lines are plotted on a logarithmic scale and not a uniform scale. Ten contour lines are used, covering a total of 100 intensity factor ranges. The large limiting width of the intensity distribution to the 10 μm slit width at a distance within about 50 μm from the slit is apparent.

  In yet another implementation, the aperture area of the pixel in the first MOSLM can be reduced to reduce the crosstalk problem in the second MOSLM.

  (2) The second approach uses a lens array between two SLMs as shown in FIG. More preferably, the number of lenses is similar to the number of pixels in each SLM. The distance between the two SLMs and the distance between the lens arrays may be slightly different to offset the difference in distance from the viewer. As shown by the light beam 171 in FIG. 17, each lens images the first SLM pixel with the second SLM pixel. Also, there will be light passing through adjacent lenses that can cause crosstalk, as indicated by the luminous flux 172. This can be ignored if its strength is such that it does not reach the VOW, or if its directionality is sufficiently different.

  The aperture number (NA: numerical aperture) of each lens must be large enough to image the pixels with sufficient resolution. As an example, at a resolution of 5 μm, NA≈0.2 is required. This means a case where some optics are assumed. If the distance between the SLM and the lens array is 10 μm, the maximum distance between the lens arrays and each SLM is about 25 μm.

  It is also possible to have one lens in the lens array for several pixels in each SLM. As an example, a group of four pixels in a first SLM may be imaged by a lens in a lens array into a group of four pixels in a second SLM. The number of lenses in such a lens array will be a quarter of the number of pixels in each SLM. This allows a higher resolution of the imaging pixel, as it allows a higher NA of the lens.

  (3) The third approach is to reduce the aperture of as many first MOSLM pixels as possible. The region of the second SLM illuminated by the first SLM pixel from the view diffraction point is determined by the aperture width D and the diffraction angle of the first MOSLM pixel, as shown in FIG. In FIG. 18, d is the distance between the two MOSLMs, and w is the distance between the two first-order diffraction minimum values that occupy either side of the zero-order maximum value. This assumes Fraunhofer diffraction or an ideal approximation to Fraunhofer diffraction.

  On the other hand, the decrease in the aperture width D decreases the direct projection area at the center of the illumination area, as shown by the broken line in FIG. On the other hand, the diffraction angle increases to be proportional to 1 / D Fraunhofer diffraction. This indicates that the width w of the illumination area on the second MOSLM increases. The illumination area has a total width w. In the Fraunhofer diffraction regime, D is determined to minimize w in a given interval d using the equation w = D + 2dλ / D obtained from the distance between two first order minimums in Fraunhofer diffraction. Also good.

  For example, if λ is 0.5 μm, d is 100 μm, and w is 20 μm, the minimum value of D in D of 10 μm is obtained. This example describes the principle of using the distance between MOSLMs to control the diffraction process in the Fraunhofer diffraction rame when the Fraunhofer ray is not a valid approximation in this example.

  (4) The fourth approach uses a fiber optic faceplate to image the first SLM pixel to the second SLM pixel. The fiber optic faceplate consists of 2D arrays of parallel optical fibers. The length of the fiber, ie the thickness of the faceplate, is usually a few millimeters, and the maximum dialog length across the plate surface is a few inches. As an example, the distance between the fibers may be 6 μm. Fiber optic faceplates with such fiber spacing are sold by Edmund Optic Inc, Burlington, New Jersey. Each fiber guides light from one end to the other end. Thus, the image on one side of the faceplate is transferred to the other side with high resolution and no focusing element. Such a faceplate can be used as a separation layer between two SLMs. Multimode fiber is preferred over single mode fiber. When the refractive index of the fiber core matches the refractive index of the liquid crystal, the coupling efficiency is optimized to minimize the Fresnel back reflection loss.

No additional cover glass is required between the two SLMs. The light that has passed through the pixels of the first MOSLM is guided to the respective pixels of the second MOSLM. This minimizes crosstalk for neighboring pixels. The face plate distributes the output of the first SLM to the input of the second SLM. On average, there should be at least one fiber per pixel. On average, if there are fewer than one fiber per pixel, the resolution of the SLM will be lost and the quality of the image shown in holographic display applications will be reduced.
An example of a small array for encoding amplitude and phase information in a hologram is shown in FIG. Reference numeral 104 denotes an illuminating device for providing illumination to a planar area. The illumination has sufficient coherence so that it can guide the generation of a three-dimensional image. US patent application 2006/250671 discloses an example of an illumination device in the case of a wide area video hologram. A device such as 104 may take the form of a cold cathode fluorescent lamp that emits light or an array of white light sources such as white light emitting diodes. These illuminations are incident on a compact focusing system such as a lenticular array or a microlens array. Alternatively, the light source at 104 may include red, green and blue lasers or red, green and blue light emitting diodes that emit sufficient coherence light. However, non-laser light sources (eg, OLEDs, cold cathode fluorescent lamps) with sufficient spatial coherence are more desirable than laser light sources. Laser light sources cause laser speckle in holographic reconstruction, are relatively expensive, and can damage the eyes of observers of holographic displays and those engaged in the assembly of holographic display devices. There are disadvantages such as safety issues regarding the possibility of giving.

  Elements 104, 100-103, 109 may have a total thickness of about a few centimeters or less. The element 101 may include an array of color filters such as pixels of colored light such as red, green, and blue light emitted toward the element 102. However, if a colored light source of light is used, a color filter is not required. The element 102 is a light polarizing element or a set of light polarizing elements. The element 103 is a MOSLM that encodes phase information. The element 109 is a MOSLM that encodes sub amplitude information. Elements 103 and 109 each include a polarizing element or a set of polarizing elements. Here, each cell of element 103 indicated by 107 corresponds to a corresponding cell of element 109 indicated here by 108. However, the cells in elements 103, 109 have similar side spaces or spacings, but the cells in element 103 are smaller than or similar in size to the cells in element 109. This is because the light emitting cell 107 typically undergoes some diffraction before entering the cell 108 of the element 109. The order in which the amplitude and phase are encoded may be reversed from that shown in FIG.

  An observer located at a point 106 at some distance from the device containing the small hologram generator 105 can see a three-dimensional image when viewing the direction of 105. Elements 104, 100, 101, 102, 103, 109 may be configured in physical contact as described above to produce a small hologram generator 105. The optical components described in Section B may be included in a small hologram generator 105 as will be apparent to those skilled in the art.

E. High-magnification 3D image display device component incorporating a small combination of one or two MOSLMs with object holographic reconstruction function Figure 19 shows one or two MOSLMs with object holographic reconstruction function 3 shows a high magnification 3D image display device component incorporating a small combination of The device components include a small combination of MOSLM and a small coherence light source. This small combination can produce a three-dimensional image that can be viewed in VOW (shown as OW in FIG. 19) under appropriate lighting conditions. The device component can be built into a PDA or mobile phone, for example. A compact combination of an SLM and a coherence compact light source comprises an array of light sources, an SLM, and a lens array, as shown in FIG. In FIG. 19, the SLM incorporates a small combination of one or two MOSLMs.

  According to a simple example, the light source array can be formed as follows. A single light source, such as a monochromatic LED, is placed adjacent to the aperture array so that the aperture is illuminated. If the aperture is a one-dimensional array of slits, the light transmitted by the slit forms a one-dimensional array of light sources. If the aperture is a two-dimensional array of circles, the illumination set of circles forms a two-dimensional array of light sources. A normal aperture width is about 20 μm. Such a light source array is suitable for generating VW for one eye.

  In FIG. 19, the light source array is located at a distance u from the lens array. The light source array may be the light source array of the element 10 of FIG. 1 or may optionally include the element 12 of FIG. Precisely, each light source of the light source array is located at a distance u from the corresponding lens of the lens array. The plane of the light source array and the plane of the lens array are parallel in the preferred implementation. The SLM may be located on either side of the lens array. VOW is located at a distance v from the lens array. The lens of the lens array is a coated lens with a focal length f given by 1 / [1 / u + 1 / v]. In a preferred implementation, v is in the range of 300 mm to 600 mm. In a particularly preferred implementation, v is about 400 mm. In a preferred implementation, u is in the range of 10 mm to 30 mm. In a particular preferred implementation, u will be about 20 mm. The magnification factor M is given by v / u. M is a coefficient when the light source modulated by the SLM is expanded in the VOW. In a preferred embodiment, M will range from 10 to 60. In certain preferred embodiments, M will be about 20. Realizing such a magnification factor with good holographic image quality requires an accurate alignment of the light source array and the lens array. Significant mechanical stability of the device components is required to maintain the exact alignment during the operational life of the component and to maintain the same distance between the light source array and the lens array.

  The VOW may be trackable or non-trackable. If the VOW is trackable and depends on the required position of the VOW, a particular light source in the light source array is activated. The actuated light source illuminates the SLM and is imaged in the observer plane by the lens array. At least one light source per lens of the lens array is activated in the light source array. Tracking is quasi-continuous. If u is 20 mm and v is 400 mm, VOW can be tracked with a lateral increase of 400 μm when the pixel pitch is 20 μm. This tracking is quasi-continuous. If u is 20 mm and v is 400 mm, f is about 19 mm.

  The light source of the light source array may have only a portion of spatial coherence. Some coherence leads to a contaminated reconstruction of object points. If u is 20 mm and v is 400 mm, the object point at a distance of 100 mm from the display is reconstructed with 100 μm lateral contamination when the light source width is 20 μm. This is fully satisfactory in the resolution of the human visual system.

  There is no need for significant coherence between the light passing through different lenses of the lens array. Coherence requirements are limited to each single lens of the lens array. Thus, the resolution of the reconstructed object points is determined by the lens array spacing. A typical lens spacing will be on the order of 1 mm to ensure sufficient resolution for the human visual system.

  VOW is limited to one diffraction order of the Fourier spectrum of the information encoded in the SLM. For a wavelength of 500 nm and an SLM pixel pitch of 20 μm, the VOW has a width of 10 mm. The VOW may be expanded by tiling the VOW by spatial multiplexing or time multiplexing. In the case of spatial multiplexing, additional optical elements such as beam splitters are required.

  Color holographic reconstruction can be realized by time multiplexing. The red, green and blue pixels of a color OLED display are operated continuously with SLM synchronous re-encoding with holograms calculated for red, green and blue light wavelengths.

  The display of which the device component forms part may comprise an eye position detector that detects the position of the observer's eyes. The eye position detector is connected to a controller that controls the operation of the light source within the light source array.

  The calculation of the hologram encoded by the SLM is preferably performed by an external encoding unit if high calculation capability is required. The display data is then sent to a PDA or mobile phone to enable display of the holographically generated 3D image.

F. 2D-projector with a small combination of one or two sets of MOSLMs. Instead of projecting light onto multiple VOWs, light from the device is projected onto a screen, wall, or some other surface May be. In this way, the three-dimensional display device can be used as a pocket projector in a mobile phone or PDA. Any other three-dimensional display device including a small combination of one or two sets of MOSLMs can be used as a projector.

  Improved quality of holographic projection may be obtained by using an SLM that modulates the amplitude and phase of incident light. In this way, complex value holograms are encoded in the SLM, resulting in better quality of the image reconstructed on the screen or wall.

  A small combination of one or two sets of MOSLMs can be used as an SLM in a projector. Due to the small size of the combination, the projector will also be small. The projector is a device similar to a mobile phone or PDA. Therefore, the mode may be switched between the “three-dimensional display” mode and the “projector” mode.

  Compared to conventional 2D projectors, holographic 2D projectors do not require a projection lens and have the advantage that the projected image is focused at all distances in the optical far field. As disclosed in WO 2005/059881, prior art holographic 2D projectors use a single SLM and thus do not have the capability of complex modulation. On the other hand, the holographic 2D projector described here has the capability of complex modulation, and can thereby obtain excellent image quality.

G. This embodiment relates to the spatial multiplexing of a virtual observer window (VOW) of a holographic display combined using 2D encoding. Alternatively, the holographic display may be as described in sections A, B, C, D, or any known holographic display.

  It is known that several VOWs, such as one for the left eye and one for the right eye, are generated by spatial or temporal multiplexing. In spatial multiplexing, both VOWs are generated simultaneously and split by a beam splitter as described in WO 2006/027228. In time multiplexing, a plurality of VOWs are generated in time series.

  However, known holographic display systems have several disadvantages. In spatial multiplexing, the lighting system used is spatially incoherent in the horizontal direction, as shown, for example, in prior art FIG. 4 taken from WO 2006/027228, Based on lenticular array. This has the advantage that known techniques can be used from autostereoscopic displays. However, there is the disadvantage that horizontal holographic reconstruction is not possible. Instead, the so-called 1D encoding used results in holographic reconstruction and motion parallax only in the vertical direction. Thus, the vertical focus is in the plane of the reconstructed object, while the horizontal focus is in the plane of the SLM. This astigmatism reduces the quality of spatial vision. That is, it reduces the quality of the holographic reconstruction that is perceived by the viewer. Similarly, time multiplexing systems have the disadvantage of requiring a high-speed SLM that is not currently available for all display sizes, and the disadvantage of being very expensive even if available. is there.

  On the other hand, 2D encoding provides holographic reconstruction that takes place simultaneously in the horizontal and vertical directions. Therefore, 2D encoding forms without astigmatism. Astigmatism results in a reduction in the quality of spatial vision. That is, it reduces the quality of the holographic reconstruction that is perceived by the viewer. Therefore, an object of the present embodiment is to realize VOW spatial multiplexing in combination with 2D encoding.

  In this implementation, the illumination system with horizontal and vertical local spatial coherence is combined with a beam splitter that splits the light into left-eye VOW and right-eye VOW beam bundles. This takes into account diffraction at the beam splitter. The beam splitter may be a prism array, a second lens array (eg, a static or variable array as shown in FIG. 20) or a barrier mask.

  FIG. 22 shows an example of implementation. FIG. 22 is a schematic diagram of a holographic display comprising a light source from a 2D light source array, a lens from a 2D lens array, an SLM and a beam splitter. The beam splitter splits the light emitted from the SLM into two light bundles that respectively illuminate the left-eye virtual observer window (VOWL) and the right-eye virtual observer window (VOWR). In this embodiment, the number of light sources is one or more, and the number of lenses is the same as the number of light sources.

  In this embodiment, the beam splitter is the latter stage of the SLM. However, the position of the beam splitter and SLM may be interchanged.

FIG. 23 is a plan view showing an embodiment in which a prism array is used as a beam splitter. The illumination system comprises an n-element 2D light source array (LS ₁ , LS ₂ ,..., LS _n ) and an n-element 2D lens array (L 1, L 2,..., Ln). Of these, two light sources and two lenses are shown in FIG. Each light source is imaged to the viewer plane by their associated lens. The distance between the light source arrays and the distance between the lens arrays are set so that all the light source images coincide with each other on an observer plane, that is, a plane including two VOWs. In FIG. 23, the left eye VOW (VOWL) and the right eye VOW (VOWR) are not shown because they are located outside the right side of the figure. Additional field lenses may be added. The spacing of this lens array is similar to the typical size of the sub-hologram in order to provide sufficient spatial coherence. That is, the calculation is from 1 to several millimeters. Illumination is horizontal and vertical spatially coherent within each lens, such that the light source is small or a point light source, or a 2D lens array is used. The lens array may be refractive, diffractive, or holographic.

  In this embodiment, the beam splitter is a 1D array of vertical prisms. Incident light at a certain tilt of the prism is refracted to the left eye VOW (VOWL), and incident light at the other tilt of the prism is refracted to the right eye VOW (VOWR). Also, the light rays emitted from the same LS and the same lens are mutually coherent after passing through the beam splitter. Thus, 2D encoding with vertical and horizontal focus and vertical and horizontal motion parallax is possible.

  The hologram is encoded with an SLM having 2D encoding. The left eye and right eye holograms are combined row by column. That is, the columns encoded with left eye and right eye hologram information are alternated. More preferably, under each prism, there are a column having information on the left-eye hologram and a column having information on the right-eye hologram. As an alternative, there may be more than one hologram row under each prism tilt. For example, there are three columns of VOWR followed by three columns of VOWL. The beam splitter spacing may be similar to multiples of SLM spacing integers (such as 2, 3) to accommodate perspective shortening, and SLM spacing integers (2, 3). Etc.) may be slightly smaller than a multiple of.

  The light from the column with the left eye hologram reconstructs the object for the left eye and illuminates the left eye VOW (VOWL). The light from the column with the right eye hologram reconstructs the object for the right eye and illuminates the right eye VOW (VOWR). In this way, each eye senses proper reconstruction. If the spacing of the prism arrays is sufficiently small, the eye cannot resolve the prism structure, which will obstruct the reconstructed image. Each eye sees reconstruction with full focus and full motion parallax, and there is no astigmatism.

  If the beam splitter is illuminated with coherent light, there will be diffraction at the beam splitter. A beam splitter is considered as a diffraction grating that produces multiple diffraction orders. The tilted prism tilt is affected by the blazed diffraction grating. In a blazed grating, the maximum intensity is directed to a specific diffraction order. In a prism array, one maximum intensity is directed from one prism slope to the diffraction order at the VOWL position, and another maximum intensity is directed from the other slope of the prism to another diffraction order at the VOWR position. Specifically, the maximum in the intensity of the envelope sinc square function is shifted to those positions, so that the diffraction order becomes a fixed position. The prism array generates a certain maximum intensity of the envelope sinc square function at the VOWL position and another maximum intensity of the envelope sinc square function at the VOWR position. The intensity of other diffraction orders is small (ie, the maximum of the sinc square intensity function is narrow), and the prism array fill ratio is large, eg, close to 100%, which does not result in inhibition crosstalk. .

  As will be apparent to those skilled in the art, in order to provide VOW to two or more observers, a more complex array of prisms (eg, arranged sequentially next to each other and at the same apex angle). More VOWs can be generated by using two types of prisms that have an asymmetric angle. However, the viewer is not individually tracked with a static array of prisms.

  In other embodiments, more than one light source per lens may be used. Additional light sources per lens can be used to generate additional VOWs for additional viewers. This is described in Patent Document 1 and describes a case having one lens and m light sources for m observers. In the above other embodiments, m light sources per lens and double spatial multiplexing are used to generate m left VOWs and m right VOWs for m observers. Yes. The m light sources per lens are m to 1 for each lens, where m is a natural number.

  An embodiment will now be described. As parameters, observer distance: 2 m, pixel pitch: 69 μm in the vertical direction and 207 μm in the horizontal direction, using Burckhardt encoding, and visible light: 633 nm and a screen diagonal of 20 inches are used. Burckhardt encoding is a vertical direction with a sub-pixel of 69 μm and a VOW height of 6 mm (vertical interval). Neglecting perspective shortening, the vertical prism array spacing is 414 μm. That is, there are two rows of SLMs under each full prism. Therefore, the horizontal interval on the observer plane is 3 mm. The same applies to the width of the VOW. This width is smaller than the optimal pupil of the eye with a diameter of about 4 mm. In yet another similar embodiment, the VOW has a width of 25 mm if the SLM is smaller than the 50 μm spacing.

  If an adult human has an eye spacing of 65 mm (as usual), the prism must refract the light by ± 32.5 mm. Thereby, the light intersects the plane including VOW. Specifically, the maximum value of a plurality of intensity envelope sinc square functions must be refracted at ± 32.5 mm. This corresponds to an angle of ± 0.93 degrees with an observer distance of 2 m. For a prism refractive index n = 1.5, a suitable prism angle is ± 1.86 degrees. The prism angle is defined as the angle between the substrate side and the tilt side of the prism.

  With respect to the horizontal spacing in the 3 mm observer plane, the other eye has a distance of about 21 diffraction orders (ie, 3 mm divided by 65 mm). The crosstalk between VOWL and VOWR can be ignored because it is caused by higher diffraction orders relative to other VOWs.

  In order to implement tracking, a simple method of tracking is light source tracking, ie the ability to adapt the light source position. If the SLM and prism array are not in the same plane, it will inhibit the associated horizontal offset between the SLM pixel and the prism caused by parallax. This results in inhibition crosstalk. The 20-inch diagonal pixel of the above example screen has a 70% fill ratio in the vertical direction relative to the axis represented by the respective prism peak. That is, the pixel size is an active area of 145 μm and an inactive margin of 31 μm on each side. If the configured area of the prism array is directed to the SLM, the distance spacing between the prism array and the SLM is about 1 mm. The horizontal tracking range without crosstalk is ± 31 μm / 1 mm * 2 m = ± 62 mm. The tracking range becomes larger if small crosstalk is acceptable. The tracking range is not large, but if it is sufficient to allow some tracking to take place, the observer will not feel much unnaturalness with respect to his eye position.

  The parallax between the SLM and the prism array can be avoided if possible by integration into the prism array or direct integration into the SLM (such as refraction, diffraction, or holographic prism array). This is a dedicated part in the product. Although the moving mechanism complicates the device, an alternative is the lateral mechanical operation of the prism array.

  Another important issue is the fixed VOW spacing given by the prism angle. This presents a troublesome problem for observers with non-standard eye spacing or for z tracking. As a solution, an assembly with an encapsulated liquid crystal region as shown in FIG. 21 can be used. This solution is used with a prism array to provide continuously variable and fixed polarization, respectively. In an alternative solution, the structured side of the prism array may be covered with a liquid crystal layer. Thus, the electric field can control the refractive index and thereby the declination. If the VOW has a large width, variable polarization assemblies are not required if sufficient tolerance exists for observers with different eye spacing or z-tracking.

  More complex solutions use a controllable prism array, such as an electro-wetting prism array (shown in FIG. 24) or a prism filled with liquid crystal (shown in FIG. 21). That would be true. In FIG. 24, the layer with prism element 159 includes electrodes 1517, 1518 and two separate liquid filled cavities 1519, 1520. Each liquid fills a cavity in the shape of a prism. As an example, the liquid may be oil or water. The inclination of the contact surface between the liquids 1519 and 1520 is determined by the voltage applied to the electrodes 1517 and 1518. If the liquid has a different refractive index, the light beam is polarized by the voltage applied to the electrodes 1517, 1518. Thus, the prism element 159 functions as a controllable beam steering element. This is an important feature in Applicants' approach to electro-holography for implementations that require tracking of VOWs to the observer's eyes. In German patent application publication 102007024237.0 and German patent application publication 102007024236.2 filed by the present applicant, which are incorporated herein by reference, the eyes of the observer using prism elements. VOW tracking is described.

  The following is an example of an implementation for a small handheld display. Seiko (registered trademark) Epson (registered trademark) in Japan has released black and white EASLM such as D4: L3D13U 1.3 inch screen diagonal panel. The use of a D4: L3D13U LCD panel as an SLM will be described as an example. The panel has an HDTV resolution (1920 × 1080 pixels), a 15 μm pixel pitch, and a panel area of 28.8 mm × 16.2 mm. Such panels are typically used in 2D (two-dimensional) image projection displays.

  In this example, the calculation is performed with a wavelength of 633 nm and an observer distance of 50 cm. Detour phase encoding (Burckhardt encoding) is used for this amplitude modulation SLM, and 3 pixels are required to encode one complex number. These three related pixels are arranged vertically. When a prism array beam splitter is incorporated into the SLM, the prism array pitch is 30 μm. If there is a distance between the SLM and the prism array, the pitch of the prism array is slightly different to reduce perspective.

  The height of the VOW is specified with a pitch of 3 * 15 μm = 45 μm to encode one complex number, and is 7.0 mm. The width of the VOW is defined by a 30 μm pitch of the prism array and is 10.6 mm. Both values are larger than the pupil of the eye. Thus, each eye can observe a holographic reconstruction when the VOW is at the eye location. The holographic reconstruction results from a 2D encoded hologram, as described above, so that the astigmatism inherent in 1D (one-dimensional) encoding does not occur. This guarantees a high quality of spatial vision and a high quality of depth.

  Since the eye spacing is 65 mm, the prism must refract light by ± 32.5 mm. Specifically, the maximum value of the strength of the envelope sinc square strength function must be refracted by ± 32.5 mm. This corresponds to an angle of ± 3.72 ° for an observer distance of 0.5 m. A suitable prism angle is ± 7.44 ° for a refractive index n = 1.5. The prism angle is defined as the angle between the substrate side and the inclined side of the prism.

  For a horizontal period in the 10.6 mm observer plane, the other eye is at a distance of approximately 6 diffraction orders (ie 65 mm / 10.6 mm). Thus, the crosstalk caused by higher diffraction orders is negligible because the prism array has a high, i.e., a fill factor close to 100%.

  An example of implementation for a large display is shown below. The holographic display can be designed to use an SLM with phase modulation having a pixel pitch of 50 μm and a screen diagonal of 20 inches. For television applications, the diagonal may rather be about 40 inches. The observer distance in the design is 2 m and the wavelength is 633 nm.

  Two phase modulation pixels of the SLM are used to encode one complex number. These two related pixels are arranged vertically and the corresponding vertical pitch is 2 * 50 μm = 100 μm. By incorporating the prism array into the SLM, each prism includes two tilts, and each tilt is used for one row of the SLM, so the horizontal pitch of the prism array is also 2 * 50 μm = 100 μm. Consequently, the 12.7 mm width and height of the VOW is larger than the pupil of the eye. Thus, if a VOW is present at the eye location, each eye can observe a holographic reconstruction. Holographic reconstruction results from 2D encoded holograms, thereby avoiding the astigmatism inherent in 1D encoding. This guarantees a high quality of spatial vision and a high quality of depth.

  Since the eye spacing is 65 mm, the prism must refract light by ± 32.5 mm. Specifically, the maximum value of the strength of the envelope sinc square strength function must be refracted by ± 32.5 mm. This corresponds to an angle of ± 0.93 ° for an observer distance of 2 m. A suitable prism angle is ± 1.86 ° for a refractive index n = 1.5. The prism angle is defined as the angle between the substrate side and the inclined side of the prism.

  The above examples relate to 50 cm and 2 m as observer distance from the SLM. More generally, the implementation can be applied for observer distances from the SLM between 20 cm and 4 m. The screen diagonal may be 1 cm (such as a mobile phone sub-display) and 50 inches (such as a large TV).

<Laser light source>
For example, RGB solid-state laser light sources based on GaInAs or GaInAsN materials are suitable as light sources for small holographic displays because of their small size and high light directivity. Such light sources include RGB vertical cavity surface emitting lasers (VCSEL) from Novalux® Inc., California, USA. Each light source can be used to generate multiple beams through the use of diffractive optical elements, but such light sources can be provided as a single laser or as an array of lasers. If the coherence is too high to use a small holographic display without causing undesirable results such as a laser speckle pattern, the beam travels through the multimode optical fiber while reducing the coherence level.

<Outline of manufacturing process>
In the following, an overview of the process for manufacturing the device of FIG. 2 is described, but many variations of the process will be apparent to those skilled in the art.

In the process of manufacturing the device of FIG. 2, a transparent substrate is selected. Such a substrate may be a rigid packaging substrate, such as a single borosilicate glass of about 200 μm thickness, or a polymeric substrate such as polycarbonate, acrylic, polypropylene, polystyrene, polyvinyl chloride or similar substrate, etc. A flexible substrate may be used. The CIAD layer is provided on the glass as described in British Patent Application Publication No. 07093766.8 and British Patent Application Publication No. 0709979.2, which are incorporated herein by reference. Such a calculation circuit is arranged between the pixels of the display. The circuit is covered with a transparent insulating film such as SiO ₂ . A magneto-optical film is provided on the transparent insulating film. A micro coil array is arranged according to the pixels of the display. A similar process is described in International Publication No. WO 2005/122479 A2. The coil material may be any conductive material such as copper or aluminum. The coil array can be manufactured with a low resistance and a large number of windings. The cylindrical groove 71 is equivalent to the depth of the magneto-optical film 72, but is etched into the magneto-optical film as shown in FIG. A conductive material is disposed in the cylindrical groove to form the microcoil 81 as shown in FIG. Here, it should be noted that the groove can be realized by laser etching. Ultrashort pulse lasers can generate picosecond or femtosecond pulses, limit the heat affected zone by high peak power, and ensure that the material removal process is performed exclusively by ablation. The magneto-optical film is realized. Then, as described above, an intermediate polarization layer and a set of the layers are generated. Additional polarization layers and sets thereof are then generated. This realizes two adjacent MOSLM device structures. Thereafter, an optical beam steering element and a glass cover layer are generated.

  The layer between two MOSLM devices may need to be thick enough so that the magnetic field present in one MOSLM does not affect the performance of the other MOSLM. The intermediate polarization layer, or set of layers, may be thick enough to achieve this goal. However, if the thickness of the intermediate polarization layer or set of layers is not sufficient, the MOSLM device can be bonded to a single glass of sufficient thickness using optical adhesion. By doing so, or by depositing a more optically transparent layer, such as the inorganic layer or polymer layer described above, the thickness of the layer can be increased. Such further optically transmissive layer may be an inorganic insulator such as silicon dioxide, silicon nitride, or silicon carbide, or may be a polymerized layer such as an epoxy. The vapor deposition treatment can be performed by sputtering or chemical vapor deposition in the case of an inorganic insulating layer, and can be performed by printing or coating in the case of a polymerized layer. However, MOSLM devices must not be too far away because the light diffraction effect causes severe crosstalk of the pixels. For example, when the pixel width is 10 μm, the distance of the MOSLM layer is preferably less than 100 μm. The LC layer of one MOSLM performs amplitude modulation, and the LC layer of the other MOSLM performs phase modulation.

  For example, using a glass layer to sufficiently separate the MOSLM layers in order to ensure that the magnetic field in each MOSLM does not affect the operation of the other MOSLMs, the first MOSLM part of the device The second MOSLM part of the device to be combined may be provided as a single unit. The second MOSLM portion of the device may be provided by depositing additional material on the first MOSLM portion of the device. In this case, there is an advantage that the alignment between the pixel of the first MOSLM and the pixel of the second MOSLM can be made accurate.

    An example of a device structure that can be fabricated using the procedure described above or a similar procedure is given in FIG. The device structure 910 of FIG. 9 is illuminated from the surface 909 by sufficiently coherent visible light radiation so that, in use, an observer at point 911 can observe a three-dimensional image. Note that the point 911 is not shown separated from the device by a distance proportional to the original size. The layers 90 to 901 in the device are not necessarily proportional to each other. The layer 90 is a substrate layer such as a glass layer. The layer 91 is a CIAD layer and may be omitted depending on an implementation example. The layer 92 is an insulating layer. The layer 93 is a magneto-optical film layer. Layer 94 is a microcoil array layer. The layer 95 is a polarization layer or a set of the layers. Layer 96 is an optional layer for providing the desired separation between the two microcoil arrays. Layer 97 is a further magneto-optical film layer. Layer 98 is a further microcoil array layer. Layer 99 is a further polarization layer or a set of such layers. Layer 900 is a beam steering element array layer. The layer 901 is a plane that covers a material such as glass. In manufacturing, the device 910 can be fabricated by starting with the substrate layer 90 and depositing each layer in turn until the last layer 901 is added. Such a procedure has the effect of facilitating that the layer of the structure can be aligned with high accuracy in the processing. Instead, the layers can be processed in two or more portions and bonded together with a sufficient degree of alignment.

  According to the implementation, it is very important for device processing to keep minimizing undesirable birefringence, such as birefringence caused by undesirable pressure. The birefringence induced by pressure gives rise to a linear or circular polarization state of the light that changes to the elliptical polarization state of the light. The presence of an elliptical light polarization state in a device where ideally a linear or circular polarization state of light would exist would reduce contrast and color fidelity and thus degrade device performance. Let's go.

  The implementations disclosed herein have emphasized successive amplitude and phase encodings in MOSLM, but any non-ideal combination of amplitude and phase, ie any complex number rather than any real multiplication. If not (except real numbers), any successive weighted encoding of the two combinations that are not correlated by being equal through multiplication can in principle be used to encode the hologram pixel. Will be understood by those skilled in the art. The reason is that the vector space of the holographic encoding of pixels that can be performed is arbitrary in the direction of the vector space, rather than any two non-ideal combinations of amplitude and phase, ie any real multiplication If it is not a complex number (except for a real number), it is stretched by any two combinations that do not have a correlation by becoming equal through multiplication.

  In the drawings herein, the relative sizes shown are not necessarily proportional to the actual size.

  Various modifications and alternatives of the present invention will become apparent to those skilled in the art without departing from the scope of the present invention, and the present invention is not unduly limited to the embodiments and implementations described herein. Should be understood.

<Appendix I: Technical Guide>
The following sections are intended as guidance for some important techniques used in some systems implementing the present invention.

  In conventional holography, an observer can observe a holographic reconstruction of an object (which may be a changing scene). However, the distance from the hologram does not matter. In one typical optical arrangement, the reconstruction is at or near the image plane of the light source that illuminates the hologram, so it is the Fourier plane of the hologram. Thus, the reconstruction has the same far-field light distribution of the real-world object to be reconstructed.

  One of the earliest systems (described in US Pat. No. 6,057,836) defines a very different arrangement in which no reconstructed object exists at or near the Fourier plane of the hologram. Instead, a region of the virtual observer window is present in the Fourier plane of the hologram, and the observer can position his eye at that position so that only the correct reconstruction can be observed. The hologram is encoded to the LCD (or other type of spatial light modulator) and the virtual observer window is the Fourier transform (and thus it is the Fourier transform that is imaged directly to the eye). Illuminated to be a Fourier transform. Therefore, since the reconstructed object does not exist in the focal plane of the lens, it is a Fresnel transformation of the hologram. It is instead defined by a near-field light distribution (modeled with a spherical wavefront as opposed to a planar wavefront with a far-field distribution). This reconstruction can appear anywhere between the virtual observer window and the LCD, or even behind the LCD as a virtual object.

  There are several consequences to this approach. First, the fundamental limitation faced by holographic video system designers is the pixel pitch of the LCD (or other type of light modulator). The goal is to allow large holographic reconstructions using LCDs with pixel pitches that are commercially available at a reasonable cost. However, this has not been realized so far for the following reasons. Where λ is the wavelength of the illumination light, D is the distance from the hologram to the Fourier plane, and p is the pixel pitch of the LCD, the periodic spacing between adjacent diffraction orders in the Fourier plane is given by λD / p. However, in a conventional holographic display, the reconstructed object is in the Fourier plane. Therefore, the reconstructed object must be smaller than the periodicity interval, otherwise its edge will bleed into the reconstruction from the adjacent diffraction orders. right. For this reason, the reconstructed objects are very small, even an expensive dedicated small pitch display, typically only a few centimeters in diameter. However, using the technique of the present invention, a virtual observer window (located in the Fourier plane of the hologram, as described above) is required only for the size of the pupil of the eye. As a result, even LCDs with reasonable pixel sizes can be used. Also, the reconstructed object can actually be very large, i.e. much larger than the periodic interval, since it can completely fill the frustum between the virtual observer window and the hologram.

  Another effect exists as well and is implemented in one variant. When calculating a hologram, for example, if a 3D (three-dimensional) image file of a racing car is created, it starts by using knowledge of the reconstructed object. The file describes how the object is viewed from a number of different viewing positions. In conventional holography, the holograms that need to generate a racing car reconstruction are derived directly from the 3D image file in a computer-intensive process. However, the virtual observer window approach allows another, more efficient technology on the computer. Starting from one plane of the reconstructed object, the virtual observer window can be calculated as the Fresnel transformation of the object. This is then achieved for all object planes by summing the results that produce the cumulative Fresnel transform. This defines a wave field that intersects the virtual observer window. Next, a hologram is calculated as the Fourier transform of the virtual observer window. Since the virtual observer window contains all the information of the object, only a single planar virtual observer window must be converted to a hologram, not a multi-plane object. This is particularly beneficial when there is no single transformation step from the virtual observer window to the hologram and there is an iterative transformation similar to the iterative Fourier transform algorithm. Each iteration step includes only a single Fourier transform of the virtual observer window instead of a transform for each object plane, resulting in a significant reduction in computer processing.

  Another interesting result of the virtual observer window is that all the information needed to reconstruct a given object point is contained in a relatively small portion of the hologram. This is in contrast to conventional holograms where information for reconstructing a given object point is distributed throughout. That means that the amount of information that needs to be processed and encoded is significantly less than conventional holograms because the information needs to be encoded in a much smaller portion of the hologram. In other words, it means that conventional computer-based devices (eg, conventional DSPs with cost and performance suitable for a large number of devices on the market) can be used even for real-time video holography. .

  However, there are parts that are less than desirable. First, in a normal hologram, the observation distance is not important, but the observation distance from the hologram is important. The hologram is encoded and illuminated in such a way that an accurate reconstruction is observed only when the eye is located in the Fourier plane of the hologram. However, there are various techniques for relaxing this Z sensitivity or its surrounding design.

  The hologram is also in such a way that the optimal holographic reconstruction can only be observed from an accurate and small viewing position (ie not only the precisely defined Z as described above, but also the X and Y coordinates). Gaze tracking may be required because it is encoded and illuminated. Along with Z sensitivity, there are various techniques for mitigating X, Y sensitivity or surrounding design. For example, as the pixel pitch decreases (as LCD manufacturing progresses), the size of the virtual observer window increases. In addition, more efficient encoding techniques (such as Kinoform encoding) facilitate the use of a greater portion of the periodic interval as a virtual observer window, thereby facilitating an increase in the virtual observer window.

  In the above description, it is assumed that a Fourier hologram is handled. The virtual observer window exists in the Fourier plane of the hologram, ie the image plane of the light source. One effect is that undiffracted light is focused on a so-called DC spot. The technique can also be used for Fresnel holograms where a virtual observer window is not present in the image plane of the light source. However, it should be noted that undiffracted light is not visible as disturbing noise. Another caveat is that the term transformation should be interpreted to include any mathematical or computational technique that is equivalent to or close to the transformation describing the propagation of light. The transformation simply approximates the physical process that is more accurately defined by Maxwell's wave equation. The Fresnel and Fourier transforms are second-order approximations, but they are algebraic as opposed to differentiation, so they can be handled in an efficient computerized manner and can be accurately implemented in an optical system. Has an effect.

  Further details are available in U.S. Patent Application Publication No. 2006/0138711, U.S. Patent Application Publication No. 2006/0139710, and U.S. Patent Application Publication No. 2006/0250671, the contents of which are shown for reference. Has been.

<Appendix II: Glossary of terms used in this specification>
(Computer generated hologram)
The computer generated video hologram (CGH) corresponding to the implementation example is a hologram calculated from a scene. The CGH can include complex values that represent the amplitude and phase of the light wave required for scene reconstruction. The CGH can be calculated, for example, by coherent ray tracing, by interference between the scene and the reference wave, or by Fourier transform or Fresnel transform.

(encoding)
This is a procedure for supplying video hologram control values to a spatial light modulator (for example, a constituent cell). In general, a hologram includes complex values that represent amplitude and phase.

(Encoded area)
The encoded region is typically a spatially limited region of the video hologram where the hologram information for a single scene point is encoded. Spatial restrictions are realized by sharp truncation or by smooth transitions realized by the Fourier transform of the virtual observer window relative to the video hologram.

(Fourier transform)
The Fourier transform is used to calculate the propagation of light in the far field of the spatial light modulator. The wavefront is represented by a plane wave.

(Fourier plane)
The Fourier plane includes a Fourier transform of the light distribution in the spatial light modulator. In the absence of a focusing lens, the Fourier plane is at infinity. When the focusing lens is in the optical path close to the spatial light modulator, the Fourier plane is equal to the plane containing the image of the light source.

(Fresnel conversion)
The Fresnel transform is used to calculate the propagation of light in the near field of the spatial light modulator. The wavefront is represented by a spherical wave. The phase element of the light wave includes a term that depends quadratically on the abscissa.

(Frustum)
A virtual frustum is formed between the observer window and the SLM and extends to the rear stage of the SLM. The scene is reconstructed in this frustum. The size of the reconstructed scene is limited by this frustum and not by the SLM periodicity interval.

(Imaging optics)
The imaging optical system is one or more optical components, for example, a lens, a lenticular array, or a microlens array that is used to form an image of one light source (or a plurality of light sources). Here, the lack of imaging optics has been described herein in the plane located between the Fourier plane and one or two SLMs when constructing a holographic reconstruction. This means that no imaging optics is used to form one or two SLM images.

(Optical system)
The light system includes a coherent light source such as a laser or a partially coherent light source such as an LED. The temporal and spatial coherence of partially coherent light must be sufficient to facilitate good reconstruction of the scene. That is, the width of the spectral line and the lateral extension of the emission surface must be sufficiently small.

(Microlens array)
Microlens arrays provide localized coherence in a small area of the display. This area is a small part of the display that encodes the information used to reconstruct a given point of the reconstructed object. Localized coherence is typically present in one microlens of the array. The sub-hologram, ie the encoded area, may be larger than a single microlens. The reconstruction point will be an incoherent superposition of several reconstructed images from different microlenses. Typically, the sub-hologram, i.e. the encoded area, extends over one or two microlenses.

(Virtual observer window (VOW))
The virtual observer window is a virtual window in the observer plane where the reconstructed 3D object is observed. VOW is the Fourier transform of a hologram and is positioned within one periodic interval to avoid multiple reconstructions of objects that are visible. The size of the VOW must be at least the size of the pupil of the eye. If at least one VOW is positioned in the observer's eye using the observer tracking system, the VOW can be much smaller than the lateral movement range of the observer. This facilitates the use of SLMs with reasonable resolution and thereby a small periodic spacing. A VOW can be imagined as a keyhole where a reconstructed 3D object can be observed, one VOW for each eye or one VOW for both eyes.

(Periodic interval)
When displayed on an SLM consisting of individually addressable cells, the CGH is sampled. This sampling causes a periodic repetition of the diffraction pattern. The periodicity interval is λD / p, where λ is the wavelength, D is the distance from the hologram to the Fourier plane, and p is the pitch of the SLM cell.

(Reconstruction)
An illuminated spatial light modulator, encoded using a hologram, reconstructs the original light distribution. This light distribution was used to calculate the hologram. Ideally, the observer would be unable to distinguish between the reconstructed light distribution and the original light distribution. In most holographic displays, the light distribution of the scene is reconstructed. In the display of the present invention, the light distribution in the virtual observer window is reconstructed.

(scene)
The scene to be reconstructed is a real or computer generated three-dimensional light distribution. As a special case, there may be a two-dimensional light distribution. A scene may constitute different objects that are fixed or moving in space.

(Spatial light modulator (SLM))
The SLM is used to modulate the wavefront of incident light. An ideal SLM could represent any complex value, i.e., the amplitude and phase of the light wave could be controlled independently. However, conventional typical SLMs control only one of the amplitude and phase characteristics with undesirable side effects that also affect other characteristics.

Claims (25)

  Holographic display device comprising at least one magneto-optical SLM.   The holographic structure of claim 1, comprising a first MOSLM and a second MOSLM, wherein the first MOSLM and the second MOSLM encode a hologram to produce a holographic reconstruction. Display device.   The holographic display device according to claim 2, wherein the first MOSLM and the second MOSLM modulate the amplitude and phase of the array of hologram pixels in an independently controlled manner.   The first MOSLM and the second MOSLM are small and in turn used to modulate the amplitude and phase of the light so that a complex number composed of amplitude and phase is encoded per pixel in the transmitted light. The holographic display device according to claim 2, comprising a small combination of   The holographic display according to claim 1, comprising a small combination of a MOSLM and a small light source of sufficient coherence, the combination being capable of generating a three-dimensional image under suitable illumination conditions. apparatus.   The holographic display device according to claim 1, comprising a high-magnification three-dimensional image display device component incorporating a small combination of one or two MOSLMs with holographic reconstruction of the object.   The holographic display device according to claim 1, wherein a small combination of one or two MOSLMs is built in and can be used as a projector. 8. A holographic display device according to any one of the preceding claims, wherein at least one SLM encodes a hologram to produce a holographic reconstruction.   9. The holographic display device according to claim 1, wherein light is modulated using a Faraday effect.   The holographic display device according to claim 9, wherein the Faraday effect is realized using a magnetic photonic crystal. The holographic display device according to claim 9, wherein the Faraday effect is realized using a doped glass fiber. The holographic display device according to claim 9, wherein the Faraday effect is realized by using a magneto-optical film.   The holographic display device according to claim 1, wherein the holographic reconstruction is visible through a plurality of virtual observer windows.   14. The holographic display device according to claim 13, wherein the plurality of virtual observer windows are arranged in a tile shape using spatial multiplexing or time multiplexing.   15. The display of any one of claims 1 to 14, wherein the display is operable to re-encode holograms on a medium including holograms for the left and right eyes of an observer in time series. Holographic display device.   16. The display is operable to re-encode time-series holograms on a medium containing holograms for the left and right eyes of each of two or more viewers. The holographic display device according to any one of the above.   The holographic display device according to claim 1, wherein the display includes an element for beam steering or a beam splitter.   The holographic display device according to claim 1, wherein the display has a CIAD layer.   The holographic display device according to claim 1, wherein the display has a line-of-sight tracking.   20. The holographic display device according to any one of claims 1 to 19, wherein the display is illuminated by a backlight and a microlens array.   The holographic display device according to claim 1, wherein the holographic display device is a television device.   The holographic display device according to claim 1, wherein the holographic display device is a monitor device.   The holographic display device according to claim 1, wherein the holographic display device is portable.   A method for manufacturing a holographic display device, comprising the steps of providing a glass substrate and successively printing or generating a layer for MOSLM on the substrate.   24. A method for generating a holographic reconstruction comprising the step of using the holographic display device according to any one of claims 1 to 23.