Abstract: A process for recording information on and reproducing information from a reflection-type holographic information recording medium, having a reflecting layer. Recording includes (i) branching a light beam from a light source into a first branched light beam and a second branched light beam, (ii) forming an information light beam from the first branched light beam by modulation with a spatial light modulation element, and (iii) recording the information by forming an interference fringe by projecting the second branched light beam as a recording reference light beam together with the information light beam onto the recording medium. Reproducing includes projecting a light beam from the light source as a reproducing reference light beam onto the interference fringe. An angle of incidence of the recording reference light beam and an angle of incidence of the reproducing reference light beam into the interference fringe are one hundred eighty degrees from one another.

Abstract: A reproducing device including a light source that emits light for reproducing recorded information to a hologram recording medium subjected to recording of information by interference fringes of signal light and reference light, a light irradiating unit that generates the reference light for obtaining a reproduced image according to the recorded information and DC light having uniform intensity and phase, and irradiates the hologram recording medium with both the reference light and the DC light and with only the DC light, a light receiving unit that performs light-reception for the DC light and the reproduced image, and performs light-reception for the DC light, and a difference calculating unit that calculates a difference between an image signal obtained based on a light-reception result of the reproduced image and the DC light, and an image signal obtained based on a light-reception result of the DC light.

Abstract: A holographic reconstruction system is disclosed with spatial light modulation means, modulating interferable light waves from light sources with at least one video hologram, comprising optical focusing means, focusing the modulated light waves with the reconstructed object light points for at least one eye position for the eyes of observers and controllable electro-optical deflector means, which direct the focused modulated light waves with the reconstructed light points to at least one eye position in order to reduce the aberrations. The reconstruction system has the optical focusing means in a field of focusing elements, wherein each focusing element is provided with at least one interferable light source. The electro-optical deflector means lie in the light path of the interferable light waves after the optical focusing mean and have at least one field of deflector elements, which has at least one separately controllable electro-optical deflector element for each focusing element.

Abstract: A method is disclosed to determine an optimal optical detector orientation to decode information encoded holographically. The method supplies a matched filter, an orientation image, a holographic data storage medium encoded with the orientation image, and an optical detector comprising a moveable input screen comprising a plurality of detector elements. The method positions the input screen in a plurality of input screen orientations and calculates a correlation factor for each of the input screen orientations. The method determines an optimal optical detector orientation using the plurality of correlation factors.

Abstract: Methods and systems for calculating a wavelength to use for a reference beam in recovering data from a holographic storage medium along with calculating a rotation and a tilt for the storage medium in data recovery. These systems and method include determining intensity levels for a plurality of windows (or subsets of pixels) for a data page as the angle of the reference beam is adjusted. The angles corresponding to the angles where the maximum intensity of light is detected for each window is then used in determining the wavelength, tilt, and rotation in recovering subsequent data pages from the holographic storage medium.

Abstract: A holographic reconstruction system is disclosed for the three-dimensional reconstruction of object light spots of a scene, comprising spatial light modulation means which modulate interference-capable light waves of illumination means with at least one video hologram, and optical focussing means which focus the modulated light waves with the reconstructed object light spots for at least one eye position of the observer's eyes. An electro-optical deflection means controlled by a system controller focuses the modulated light wave with the reconstructed object light spots on at least one eye position and tracks them when the eye position changes. The electro-optical deflection means is a controllable optical diffraction grating with a variable surface relief structure consisting of separately controllable microcells.

Abstract: In known light modulation means, complex phase and amplitude values for modulating light waves are implemented and modulated either separately by two different light modulation means or a light modulation means having two layers of double-refracting materials, leading to increased expenses for material and adjustment. A new device is disclosed that simplifies the modulation of light waves in phase and amplitude in a single light modulation means made of double-refracting material. In a device having regularly disposed, controllable light-modulated elements having a double-refracting material for complex modulation of coherent light waves, and a modulation controller controlling the force-induced alignment of the optical axes of the molecules of the double-refracting material, means are provided for independently aligning the optical axes of the molecules in the light-modulating elements in two dimensions. The alignment can take place by electrical, magnetic, or optical acting means.

Abstract: A multilayer holographic recording medium that improves recording density and data transfer rates. The multilayer holographic recording medium, from which information is reproduced by a multilayer holographic memory reproducing apparatus, includes a plurality of deposited holographic recording layers. During recording, a reference beam is common to those holographic recording layers and an incident angle of an object beam is modulated for each holographic recording layer. During reproduction, a laser beam for reproduction having the same condition as that of the reference beam used for recording is projected thereonto, so that diffraction beams are simultaneously generated in the respective holographic recording layers to directions that are the same as incident directions of the object beam used for recording.

Abstract: An apparatus includes: a light source; a splitting unit that splits a light beam into an information beam and a reference beam; a spatial light modulator that modulates the information beam into a grating binary pattern having bright points and dark points; an irradiation unit that irradiates the reference beam and the information beam onto a hologram recording medium to record information corresponding to each of the regions of the spatial light modulator; a photodetector that detects a signal beam that is diffracted from the hologram recording medium by irradiating the hologram recording medium with a reproduction beam emitted by the light source; and a power detector that detects a difference of powers of signal beams detected by the photodetector at portions in the hologram recording medium corresponding to two of the regions of the spatial light modulator.

Abstract: A holographic reconstruction system and a corresponding holographic reconstruction method are disclosed. The holographic reconstruction system comprises light source means for providing substantially coherent light, reconstruction means for holographically reconstructing a scene and for producing a visibility region from where the viewer can view the holographically reconstructed scene, and deflection means for positioning the visibility region. The aim of the invention is to improve the visibility region of a holographic reconstruction system. To achieve this aim, the holographic reconstruction system comprises deflection drive means for continuously rotating or pivoting the deflection means about a rotational axis at a rotary frequency, thereby displacing the visibility region.

Abstract: Various embodiments of the present invention relate to dynamically reconfigurable hologram comprising a phase-modulation layer and an intensity-control layer. The phase modulation layer comprises an electronically programmable erasable negative index material crossbar. The crossbar includes a first layer of approximately parallel nanowires (502) and a second layer of approximately parallel nanowires (504) that overlay the nanowires in the first layer. The nanowires in the first and second layers have substantially regularly spaced fingers. The crossbar also includes resonant elements (812) comprising two fingers of a nanowire in the first layer, two fingers of a nanowire in the second layer, and an intermediate layer (1006,1302) sandwiched between the nanowire in the first layer and the nanowire in the second layer. The refractive index of each resonant element is controlled by changing the charge density within the intermediate layer.

Abstract: Disclosed is a holographic display including a spatial light modulator, and including a position detection and tracking system, such that a viewer's eye positions are tracked, with variable beam deflection to the viewer's eye positions being performed using a microprism array which enables controllable deflection of optical beams.

Abstract: A holographic memory system is disclosed. The holographic memory system comprises: a light source configured to generate a light beam; a photosensitive holographic storage medium configured to at least partially reflect the light beam; and an alignment module configured to determine an angular orientation of the storage medium based on the reflected light beam.

Abstract: A method is disclosed for reconstructing a three-dimensional scene in a holographic display. A 3D scene that is to be reconstructed is decomposed into object points, and one respective object point is encoded as a sub-hologram in the light modulator. Processor means and reconstruction means are provided for calculating and encoding as well as for reconstructing the 3D scene in order to overcome known drawbacks encountered when encoding a hologram and holographically reconstructing the 3D scene in holographic display devices. Processor elements are provided for generating a movable two-dimensional grid in the light modulating means, forming groups of object points from grid-related object points, and sequentially encoding the holograms of said groups of object points, by means of which intrinsically coherent partial constructions of the groups of object points are generated in a rapid sequence, said partial constructions being incoherent relative to one another.

Abstract: The invention relates to a method for generating video holograms for a holographic reproduction device with at least one light modulation means, wherein a scene split into object points is encoded as a whole hologram and can be seen as a reconstruction from a visibility region, which is located within a periodicity interval of the reconstruction of the video hologram. The visibility region, together with each object point of the scene to be reconstructed, defines a subhologram and the whole hologram is generated from a superposition of subholograms, wherein in a sequence of image contents the difference subholograms of object points are preferably generated for each picture, differing in regards to the visibility according to the viewer position in sequential images of the sequence. The display device comprises means that provide high-quality video holograms in spite of the data amount being significantly reduced.

Abstract: A projection device having a coherent light beam-generator that generates a light beam and a beam expander disposed to receive the light beam and to emit an expanded light beam. The projection device also includes a digital micro-mirror device disposed to receive a holographic transform of an original image and to display the holographic transform for illumination by the expanded light beam into a holographic light beam with a convergent or focusing lens disposed to receive and modulate the holographic light beam and a liquid crystal plate volumetric image reconstructor that receives the focused holographic light beam and emits a 3-dimensional holographic image of the original image.

Abstract: A method for holographic storage data recovery in a holographic storage system is presented. One exemplary method includes detecting a stored image at a detector such that the image is oversampled. A relationship is determined between a location of the detected image and a location of the source image. Pixel information associated with the source image may be obtained from the detected image based on a fractional delay filter. In one example, the image may be oversampled by magnifying the detected image at the detector and/or having a detector with pixel sizes and spacing less than the image pixel size. Further, coefficients of the fractional delay filter may be determined, at least in part, on magnification and shift information of the image based on known registration marks.

Abstract: An apparatus for recording or reading high areal density holographically stored information with high signal-to-noise ratio. The apparatus comprises a holographic imaging system for recording or reconstructing a holographic image, having a first numerical aperture and a first focal length and an additional optical system for filtering the signal beam, having a second numerical aperture and a second focal length, wherein the numerical aperture of the additional optical system is less than the numerical aperture of the holographic imaging system and/or the focal length of the additional optical system is greater than the optical length of the holographic imaging system.

Abstract: A holographic recording and reproduction apparatus (100) includes a spatial light modulator (112) for spatially modulating a luminous flux for holographic recording of information and an objective lens (106) for focusing object light and reference light for recording on a recording medium. The spatial light modulator (112) is controlled by a control device for generating a two-dimensional digital pattern corresponding to the information, that includes n first sub sets each including sixteen elements. The first sub set includes four second sub sets, and each second sub set has four elements. The control device sets one element among the elements included in each of three second sub sets among the four second sub sets to a first state and sets three elements to a second state, and sets four elements included in one remaining second sub set among the four second sub sets to the second state.

Abstract: A system and method for recording and reproducing holographic interferogram with servos. A servo process is provided by the system and method to continuously record a holographic interferogram in a holographic recording medium with servo trace layers. Also, by the servo process, the intensity distribution of a reference beam is monitored, which is reflected by a reflecting mirror disposed on the other side of the holographic recording medium. By analyzing the distribution, one can adjust the distance and the incidence angle between the reflection mirror and the reference beam. Moreover, a plurality of servo tracks on different layers are provided for recording the holographic interferogram on different layers of holographic recording medium.

Abstract: The invention relates to a security system especially for security documents, wherein a security element is provided in a carrier plane, that under incident light holographically reconstructs a pattern outside the carrier plane, in which concealed information is stored and having a flat transparent verification element which on flat contact with the security element makes the information stored therein visible. The invention further relates to a security element and a verification element for use in the security system and a security document fitted with the security system. The invention additionally relates to an apparatus and a method for reading out the concealed information which is stored holographically in the pattern reconstructed on the security element under incident light.

Abstract: A hologram reproduced image position detecting method used in a hologram apparatus which perfoming an image formation with light reproduced from a recording medium where a data page including a marker and a data area that have been displayed on a spatial light modulator is recorded, on an image sensor having a larger number of pixels than the spatial light modulator, thereby obtaining a reproduced image of the data page to reproduce the data page. The detecting method comprises the steps of storing a template image into which the marker has been interpolation-expanded, beforehand; oversampling the reproduced image of the data page in the image sensor to obtain a detected image; and performing a template matching process on the detected image using the template image, thereby detecting the position of the marker when recorded.

Abstract: A recording medium records therein image data for distributing contents as element holograms with interference fringes generated by interference between an object beam representing the image data and a reference beam. The image data to be distributed which are recorded as the element holograms in the recording medium are reproduced by applying reference beams to the recording medium.

Abstract: A holographic projection system has an optical wave tracking system which adjusts the propagation direction of a modulated wavefront. It provides an adjustable wave tracking system which aligns the modulated wave with a desired eye position of one or more observers and follows the movements of the observer. The system comprises spatial light modulation means which modulate a wave with holographic information for the purpose of holographic reconstruction. The optical wave tracking provides the light path of the modulated wave with a desired propagation direction which guides the modulated wave out of the reconstruction system via a light exit position of a display screen. Position control means set adjustable tracking mirror means in terms of their inclination to a reflection direction for reflecting the modulated wave and deflection means, which are located in the set reflection direction, reflect the wave via the display screen into the desired propagation direction.

Abstract: A reproduction device includes a light-emitting unit that emits reference light and coherent light, which is generated so as to have uniform light intensity and uniform phase, onto a hologram recording medium on which data is recorded by an interference pattern of signal light and the reference light, and a light-attenuating unit that attenuates the light intensity of the coherent light.

Abstract: A three-dimensional (3D) color display apparatus may include: light sources emitting different color beams; a volume diffractive element, in which a hologram is recorded using one of the color beams that is emitted from one of the light sources as a reference beam and a signal beam, displaying color images by diffracting the color beams emitted from the light sources; and a scanning unit scanning the color beams diffracted by the volume diffractive element. A 3D color image display method may include: recording holograms in a volume diffractive element using a first color beam as a reference and signal beam; irradiating the first color beam and another color beam onto the volume diffractive element as a reproducing reference beam; forming beam spots by diffracting the first color beam and the another color beam using the volume diffractive element; and scanning the color beams diffracted by the volume diffractive element.

Abstract: A recording medium records therein image data for distributing contents as element holograms with interference fringes generated by interference between an object beam representing the image data and a reference beam. The image data to be distributed which are recorded as the element holograms in the recording medium are reproduced by applying reference beams to the recording medium.

Abstract: The invention relates to a holographic reconstruction system for the reconstruction of scenes having at least one video hologram modulated wave front, and an enlarged visibility region. The system utilizes two-dimensional coded light modulator cells of spatial light modulation means and optical focusing means, which realize a Fourier transformation of the modulated wave front in their focal plane. First optical deflection means deflect the parallel disposed partial light waves such that their Fourier transformations appear as cascading in the focal plane. A spatial frequency filter located on the focal plane, lets each of the same diffraction orders of all modulated partial light waves pass, and second optical deflection means arrange the wave front strips next to each other at the modulated wave front, which reconstructs the scene.

Abstract: A holographic projection device comprises for the reconstruction of scenes at least one light source which emits sufficiently coherent light for the generation of a wave front. Further, the projection device comprises at least one light modulator device containing modulation elements, said projection device being of a two-dimensional design. The light modulator device and a scanning element are combined such that the light emitted by the scanning element only scans one one-dimensional arrangement of modulation elements of the two-dimensional light modulator device at a time.

Abstract: An apparatus for recording or reading high areal density holographically stored information with high signal-to-noise ratio. The apparatus comprises a holographic imaging system for recording or reconstructing a holographic image, having a first numerical aperture and a first focal length and an additional optical system for filtering the signal beam, having a second numerical aperture and a second focal length, wherein the numerical aperture of the additional optical system is less than the numerical aperture of the holographic imaging system and/or the focal length of the additional optical system is greater than the optical length of the holographic imaging system.

Abstract: A method is provided for manufacturing a holographic medium by recording holograms in transmission geometry, and applying a reflective layer to one side of the holographic recording material after recording is completed (alternatively, for example, the playback system may contain a reflective surface or mirror). For readout, the reference beam is incident to the media from a side opposite the reflective layer. This beam propagates through the media to the reflective layer on the opposite side, and is reflected back through the media for readout of the transmission hologram. The diffracted hologram signal also exits the media on the side without the reflective layer, where it can be recovered by a detector on the same side as the laser source. Alternatively, the readout reference beam is positioned so that the incident beam reads out the hologram, and both the reference beam and diffracted hologram are reflected back through the media.

Abstract: A method and a device for encoding and reconstructing computer-generated video holograms using a conventional LC display: it provides holographic reconstruction of three-dimensional scenes using electronically controllable pixel in a holographic array (3) with a conventional resolution, and is reasonably free from flickering and cross-talk. Reconstruction is in real time, and for both eyes at the same time, over a large viewing zone. The method takes advantage of an optical focusing means (2) in order to image vertically coherent light emitted by a line light source (1) into viewing windows (8R, 8L) after modulation by the pixel array (3). The holographic reconstruction (11) of the scene is rendered visible from viewing windows (8R, 8L) for both eyes of an observer by way of diffraction at the pixels.

Abstract: Systems and methods for recovering data in a holographic memory system. The systems and methods use homodyne detection to introduce a local oscillator beam into a reconstructed data beam of the recovered hologram. An image of the combined beam comprising the reconstructed data beam and local oscillator beam may be processed to obtain contrast level information for the pixels of the detected image. This contrast level information may then be used to obtain an increased contrast image of the recovered hologram, which may increase the SNR of the recovered data.

Abstract: A hologram-reproducing method is adapted to obtain a reproduced image by irradiating a hologram-recording material with a reference-light beam so that a reproduction signal-light beam is generated and picking up an image of the reproduction signal-light beam. The hologram-reproducing method includes the steps of generating a plurality of reproduced images by irradiating the hologram-recording material with a plurality of reference-light beams and generating a single reproduced image by performing image processing for the plurality of reproduced images.

Abstract: Systems and methods are provided for projecting a virtual image of an object. A projector mounted on the object for projecting a light beam. A photographic plate is provided that includes an interference pattern imprinted onto at least one surface, wherein the interference pattern manipulates the light to form a hologram beam such that a detector detecting the hologram beam detects a virtual image of the object that has a light signature at a greater intensity than a light signature of the object.

Abstract: A hologram recording and reproducing apparatus includes a movable galvanomirror, a mirror controller and a reproduction unit. The galvanomirror guides a reference beam toward a hologram recording medium and changes the incident angle of the reference beam. The mirror controller causes the galvanomirror to move for adjusting the incident angle to a predetermined angle for hologram recording. In reproducing the recorded information, the mirror controller causes the galvanomirror to move, so that the incident angle continuously changes within a predetermined range including the predetermined angle. The reproduction unit receives a detection signal from an optical detector while the incident angle changes continuously. The detection signal corresponds to the intensity of a reflected beam from the hologram recording medium. The reproduction unit reproduces the recorded information, based on the detection signal, when the intensity of the reflected beam is over a predetermined level or reaches the maximum.

Abstract: In a method for production of documents with a hologram and a document with a hologram, wherein, in a first step, a hologram is exposed in a photographic film and, in a second step, the photographic film is applied to a document support, the individualisation of the holograms first occurs during the gluing or after the gluing to the printed personal document or to the protective film provided for the surface protection of the document. It is thus possible to produce in a secure and economical fashion documents with individual holographic information of greater visibility and with further novel security features.

Abstract: An object of the present invention is to provide an electron microscope that employs a hologram of a diffraction pattern to reconstruct a microscopic image involving no imaging aberration due to image forming lenses, as well as a combined illumination lens used for such an electron microscope.

Abstract: A holographic display includes a spatial light modulator (SLM), a light source arranged to illuminate the SLM, and replay optics arranged to focus light reflected from the SLM to present a three dimensional image. The light source appears substantially at a zeroth order point of the replay optics, such that light from the light source is directed through the replay optics before illuminating the SLM.

Abstract: A lighting apparatus is provided. The lighting apparatus includes a power supply housing section, a circuit board housing section, a light source housing section, a cutout portion, and a light source. An image recorded on a record medium is displayed in the state that an end portion of the power supply housing section and an end portion of the record medium secured to the cutout portion are placed on a surface where the lighting apparatus is placed.

Abstract: A hologram reconstructing apparatus configured to irradiate a hologram recording medium that stores an interference pattern of a signal beam spatially modulated by data displayed on a spatial modulator and a reference beam emitted simultaneously with the signal beam with a reconstructing reference beam and to reconstruct data by capturing a reconstruction signal beam generated at the hologram recording medium being irradiated includes an image pickup unit that receives a partial reconstruction signal beam that constitutes part of the reconstruction signal beam by a full light-receiving plane; and a moving unit that relatively move the light-receiving surface of the image pickup means within an irradiation range of the reconstruction signal beam.

Abstract: The invention relates to a display system for diagnostic image systems for reproducing three-dimensional medical images. The display system has at least one holographic projection facility that is connected to the diagnostic image system. The projection device reproduces a hologram of the three-dimensional medical images in an examination or intervention room.

Abstract: A hologram media reading apparatus including a reference light source, a stop with gray level aperture, and an optical sensor is provided. The reference light source is disposed on one side of a hologram medium, and capable of emitting a reference light beam. The reference light beam is transmitted to the hologram medium. The stop with gray level aperture and the reference light source are disposed on the same side or opposite sides of the hologram medium. The stop with gray level aperture has a light transmissive region, an opaque region, and a transmittance gradually varying region. The opaque region surrounds the light transmissive region. The transmittance gradually varying region surrounds the light transmissive region. A part of the reference beam from the hologram medium passes through the stop with gray level aperture and is transmitted to the optical sensor.

Abstract: A method and apparatus for performing reproduction position servo-control without reducing the recording capacity of a holographic recording medium. Upon the reproduction of a holographic recording medium 18, part of a reproduction beam serving as a servo beam is projected onto a recording layer 18A of the holographic recording medium 18 from the side opposite to the side of the reproduction beam (a reference beam) along the same optical axis as that of the reproduction beam, and the diffraction beam thereof is detected by a photodetector 26C through a polarizing beam splitter 26B.

Abstract: The invention relates to an apparatus for transmissively reading out holograms generated by writing light in an optical medium, in particular holograms generated in an optically addressable spatial light modulation device. For this purpose, the apparatus comprises an illumination device for emitting light and an optical system for directing the light from the illumination device onto the optical medium. In this case, the optical system is arranged in the beam path of the writing light.

Abstract: A hologram information reproducing device is described which can reproduce information from a recording medium on which hologram information is recorded, and which can be downsized. In one aspect, when light from a light source is emitted, the light is converted into parallel reference light, by a lens of an optical system. A mirror changes the orientation of the reference light so that it is oriented obliquely downward towards a recording medium. More specifically, as viewed from the top, the mirror changes a path of the light from the light source unit by approximately 90 degrees. In addition, as viewed from the side, the mirror changes the path of the light from the light source unit downward by approximately 45 degrees. Since an interference pattern recorded on the recording medium is a Bragg grating, when the reference light illuminates a recording area of the recording medium, a reproduction light is obtained by Bragg diffraction.

Abstract: Disclosed is a hologram recording method using a beam with a very large incident angle, a hologram reproduction apparatus using a holographic reflector, a hologram reproduction method using the same and a flat display element apparatus using a holographic reflector. The hologram recording method using a beam with a very large incident angle comprises the steps of generating a sheet beam as the reference beam, and introducing the reference beam into the recording medium at an incident angle of at least 70°. The hologram reproduction apparatus using a holographic reflector comprises a light, a holographic reflector, an adjustor, and a hologram.

Abstract: This invention relates to improved techniques for reading holograms, in particular volume reflection holograms, and to improved security documents incorporating volume reflection holograms.

Abstract: Methods and systems are provided for obtaining a phase conjugate reconstruction beam for use in retrieving holographic information from a holographic storage medium. These methods and systems include generating a coherent light beam that is a reproduction of the reference beam used in storing the holographic information in the storage medium. This coherent light beam is then directed through the holographic storage medium at the same angle and location of the reference beam during recording of the hologram. The directed coherent beam is then reflected back through the storage medium so that the reflected coherent light beam provides a phase conjugate of the reference beam and passes through the storage medium at the same angle and location that the reference beam passed through the storage medium during recordation of the hologram.

Abstract: A multi-color off-axis digital holographic system and the imaging method thereof are disclosed. The multi-color off-axis digital holographic system comprises: a plurality of light emitting diodes, for provide a red (R) beam, a green (G) beam and a blue (B) beam; an interference object lens module, for receiving the R, G, and B beams to generate a beam containing an interference signal; a color imaging device, for receiving the beam containing the interference signal and thus forming a hologram on a surface of the color imaging device by holographic interference while registering the hologram; and a processing device, for receiving the registered hologram form the color imaging device; wherein the processing device perform a zero-filling and reconstructing operations upon the received hologram to obtain phase information of the R, G and B beams.