Abstract: A hologram imaging device for obtaining hologram images and associated document markings which are commonly being used for document verification is disclosed. The imaging device comprises a housing defining an imaging chamber, camera, hologram light source, document light source and imaging platform. The hologram light source consists of a series of illumination devices (e.g., LEDs) adjustably mounted in an arc or semicircular arrangement. An LED controller regulates the state of the LEDs by controlling whether each LED is on or off and adjusting the intensity of each LED in an on position. During use, a document is secured within the housing by the imaging platform such that a hologram or other document marking is positioned beneath a camera lens. Then, the LEDs of the hologram light source are regulated by the LED controller such that different images and/or colors of the hologram may be captured by the camera.

Abstract: A system and method capable of providing high data rate data copying and recording in holographic data storage while maintaining the copied data's signal-to-noise ratio. This is achieved by using optically-based parallel signal processing. In one preferred embodiment, the present invention uses a plurality of optical resonating cavities to provide thresholding and gain functions via positive feedback.

Abstract: A hologram fabricating apparatus includes a coherent light generator, two micro-display devices and a telecentric system. The coherent light generator provides a first coherent light and a second coherent light. Each micro-display device has a plurality of pixel elements laid thereon. The first coherent light and the second coherent light project respectively to the two micro-display devices. The telecentric system is located between the micro-display devices and a photoresist sheet to converge the projecting light on the photoresist sheet to generate interference stripes. Each pixel element may be adjusted independently to determine whether the first coherent light and the second coherent light projected to the pixel element to be projected to the telecentric system.

Abstract: Disclosed are optical systems and methods of producing obliquity corrected light beams, for example, holographic recording and retrieval systems that utilize an obliquity corrected reference beam. One method includes directing a light beam reflected from a prism mirror to a reference plane with an angle of incidence to the reference plane, wherein the prism mirror varies the width of the light beam according to the angle of incidence to the reference plane. The optical system may include a holographic data storage system and the reference plane may be associated with a holographic storage medium.

Abstract: A mirror angle measurement and a servo control apparatus for a Holographic Digital Data Storage (HDDS) system is disclosed. The mirror angle measurement apparatus includes a first mirror having a first reflecting surface by which the reference beam is reflected toward the holographic medium, and a second reflecting surface by which a control beam is reflected to adjust the incident angle of the reference beam; a transmission unit for causing control beam to the second reflecting surface; a second mirror for returning the control beam to the second reflecting surface; and a photo detector unit for detecting the amounts of the control beam. The angle of the first mirror is adjusted based on a comparison result between the amounts of the control beam detected by the photo detector unit.

Abstract: An optical information recording/reproducing apparatus generates information light by modulating light emitted by a light source device with a light modulator depending on the information to be recorded and generates reference light for recording by modulating the light emitted by a light source device with a light modulator. The information light and the reference light for recording are projected upon an optical information recording medium such that they converge in different positions, and information is recorded in a hologram layer in the form of an interference pattern between the information light and the reference light for recording.

Abstract: The invention relates to a lithograph for producing digital holograms in a storage medium (4), having a light source (6, 10) for producing a write beam (12) with a predefined beam cross section, having a writing lens (14) for focusing the write beam (12) onto the storage medium (4) to be written, the writing lens (14) being arranged in a lens holder (16), and having drive means for the two-dimensional movement of the write beam relative to the storage medium. The technical problem of writing computer-generated holograms as quickly as possible and with little effort by means of optical lithography is solved in that a first drive device (18) is provided for moving the lens holder (16) substantially at right angles to the write beam (12) and in that the aperture of the writing lens (14) is smaller than the beam cross section of the write beam (12). The inventon also relates to a method for the lithographic production of a hologram in a storage medium.

Abstract: A method of fabricating a holographic mask includes the steps of providing an illumination source and a non-opaque object mask. The source is for generating a coherent illumination beam directed along an axis. The object mask is capable of transmitting a portion of the illumination beam as undiffracted reference wavefronts. The object mask has one or more substantially transparent elements for creating overlapping object wavefronts when the illumination beam is incident thereon. The object mask is disposed in the illumination beam. A holographic recording medium is provided in the illumination beam in line optically with the object mask. The object mask is illuminated with the illumination beam, thereby causing the object mask to allow undiffracted reference wavefronts to pass therethrough. The illumination directed along the axis causes the one or more substantially transparent elements to create object wavefronts which interact with the undiffracted reference wavefronts to create an interference pattern.

Abstract: The present invention relates to a method and an apparatus for forming a hologram from a mask. According to the invention a photoresist is used as the holographic recording medium and the planes of polarisation of the object and reference beams incident on the holographic recording medium are arranged such that their polarisation vectors are substantially mutually orthogonal in the holographic recording medium and such that the polarisation vectors of the incident and totally internally reflected reference beams are also substantially orthogonal. Preferably, just the transmission hologram is formed in the holographic recording layer.

Abstract: Disclosed herein is a method, system and computer readable medium for a distortion-tolerant 3-D object recognition that may include recording a single exposure digital hologram of a 3D object on a sensor by on-axis digital holography; representing the recorded single exposure digital hologram mathematically as a synthesized hologram and as a reconstructed complex wave function of the 3D object; repeating the steps above for at least one comparison 3D object and obtaining a comparison reconstructed complex wave function of the comparison 3D object; and constructing a correlation filter for 3D distortion-tolerant object recognition from the reconstructed complex wave function of the 3D object and from the at least one comparison reconstructed complex wave function of the comparison 3D object also recorded; and correlating the reconstructed complex wave function of the 3D object to the comparison reconstructed complex wave function of the comparison 3D object using the correlation filter in order to recognize 3D

Abstract: The invention is directed to holographic recording techniques that generate a data encoded object beam and a reference beam using a spatial light modulator of the holographic recording system. An input light source, e.g., comprising laser light conditioned by optical elements, can be used to illuminate the spatial light modulator. Different portions of the spatial light modulator are used to create the data encoded object beam and the reference beam, which are then made to interfere in a holographic medium to record a hologram.

Abstract: The invention is directed to holographic recording techniques that generate a data encoded object beam and a reference beam using a spatial light modulator of the holographic recording system. An input light source, e.g., comprising laser light conditioned by optical elements, can be used to illuminate the spatial light modulator. Different portions of the spatial light modulator are used to create the data encoded object beam and the reference beam, which are then made to interfere in a holographic medium to record a hologram.

Abstract: Optical information is stored in an optical information recording medium having an information recording layer utilizing holography with an optical information recording apparatus which includes security features. An input device is used to input individual information which is unique to an individual. An information light carries information to be recorded on the optical information recording medium. A phase modulation pattern is generated based on the individual information. A recording reference light is generated including a phase modulator for spatially modulating a phase of the reference light, for generating reference light for recording having a phase spatially modulated based on the phase modulation pattern information. A recording optical system illuminates the information recording layer on the same side with both the information light and the reference light.

Abstract: The present invention makes it possible to reduce the size of an optical system for multiplex recording or reproduction of information utilizing holography. A pick-up of an optical information recording/reproducing apparatus generates information light by spatially modulating laser light emitted by a laser source device with a spatial light modulator depending on the information to be recorded and generates reference light for recording having a spatially modulated phase by spatially modulating the phase of laser beam emitted by the light source device with a phase-spatial light modulator. The information light and the reference light for recording are projected upon an optical information recording medium such that they converge in different positions, and information is recorded in the hologram layer in the form of an interference pattern as a result of interference between the information light reflected by a reflecting film and the reference light for recording.

Abstract: A hologram recording apparatus, a hologram recording method and a hologram recording medium reduce noise components generated by a phase modulation type spatial light modulator, thus permitting improved integrity of data to be achieved. A light beam whose diffraction state has been controlled by a diffraction control element is condensed on a hologram recording medium. With this arrangement, a predetermined diffracted light component is removed from a diffracted light beam emergent from the diffraction control element when recording information, which is based on the diffraction state controlled by the diffraction control element, in a hologram recording medium. Thus, noise components when information is recorded can be reduced.

Abstract: A method for monitoring diffraction while reading a hologram includes: illuminating a holographic medium with a reference beam to generate a data beam for a hologram that has been recorded at a set diffraction efficiency with a first polarization, the reference beam having a second polarization; and measuring an offset component in an output arm of the data beam.

Abstract: An apparatus for detecting a hidden image, which is formed in a first area of a hologram, is disclosed. The apparatus has a laser device for generating a laser beam and projecting the laser beam to the hologram, and a sensing device for sensing light that reflects from the hologram. When the laser beam is emitted to the hologram at a first incident angle, at least one diffractive beam is generated by diffraction of the laser beam. The sensing device is capable of outputting a responding signal according to the characteristics of the diffractive beam. Additionally, if the laser beam is emitted to the hologram at an incident angle, which is not equal to the first incident angle, the diffractive beam cannot be generated so that the sensing device does not output the responding signal.

Abstract: The present invention provides a single method and apparatus for producing many of the most common types of hologram from digital data is disclosed. The data are generated entirely by a computer as a 3-D (animated) model or from multiple 2-D camera images taken of a real 3-D (moving) object or scene from a plurality of different camera positions. The data are digitally processed and displayed on a small high resolution spatial light modulator (SLM). A compact low energy pulsed laser, is used to record composite holograms. The present invention permits the creation of restricted or full parallax master transmission or reflection type composite holograms, known as H1 holograms, that can be copied using traditional methods. Alternatively the same invention and apparatus permits the direct writing of hologram without the need to pass through the intermediate stage of the H1 transmission hologram.

Abstract: Pre-sensitization techniques can be used in conjunction with holographic recording materials to allow high quality holographic stereograms to be recorded in those holographic recording materials using pulsed lasers. Additional hologram production system hardware and software designs for use with pulsed lasers are disclosed.

Abstract: An apparatus for forming a nano grating device to film nano-scale interference fringes by holography in order to makes a nano-scale meshed structure is disclosed. A beam emitted form a light source passes subsequently through a beam splitter and two reflectors to reach at symmetrically mounted light emitting modules. The light emitting modules generate two beams passing along the same optical paths and then projecting on a photosensitive substrate that is attached on a hemi-sphere lens. Thus, a first set of interference fringes are formed. Then, the substrate rotates with an angle and then is subjected to exposure to form a second set of interference fringes crossing the first set of interference fringes. Thereby, a nano-scale meshed structure is obtained.

Abstract: The present invention provides a single method and apparatus for producing many of the most common types of hologram from digital data is disclosed. The data are generated entirely by a computer as a 3-D (animated) model or from multiple 2-D camera images taken of a real 3-D (moving) object or scene from a plurality of different camera positions. The data are digitally processed and displayed on a small high resolution spatial light modulator (SLM). A compact low energy pulsed laser, is used to record composite holograms. The present invention permits the creation ofrestricted or full parallax master transmission or reflection type composite holograms, known as H1 holograms, that can be copied using traditional methods. Alternatively the same invention and apparatus permits the direct writing of hologram without the need to pass through the intermediate stage of the H1 transmission hologram.

Abstract: This invention relates to the field of holography, in particular to a method and a device for recording optical holograms by means of amorphous molecular semiconductor (AMS) films deposited on a glass substrate pre-covered with a transparent electric conducting sub-layer. More precisely, the invention relates to a method and device for registering optical holograms on AMS-films which operates in such a way that the AMS-films possess the maximum achievable information parameters: Holographic sensitivity, optimal spatial frequency of the transmitted characteristic, band parameters for the spatial frequencies of the transmitted characteristic, “signal-to-noise” ratio in the restored holographic image, reference and object beam intensities ratio during hologram registration, and cycling ability.

Abstract: In an apparatus for detecting holographic data reproduced from a holographic medium, the holographic medium has an interference pattern and the holographic data is reproduced when a first portion of a reference beam is diffracted by the interference pattern within the holographic medium. A transmission beam detector detects a light intensity of a transmission beam which is a second portion of the reference beam, wherein the transmission beam is not diffracted to reproduce the holographic data and passes through the holographic medium. Then, a CCD (charge coupled device) controller generates a driving signal in accordance with the detected light intensity. Thereafter, a CCD detects the holographic data in response to the driving signal.

Abstract: The present invention makes it possible to reduce the size of an optical system for multiplex recording or reproduction of information utilizing holography. A pick-up (11) of an optical information recording/reproducing apparatus generates information light by spatially modulating laser light emitted by a light source device (25) with a spatial light modulator (18) depending on the information to be recorded and generates reference light for recording having a spatially modulated phase by spatially modulating the phase of laser beam emitted by the light source device (25) with a phase-spatial light modulator (17). The information light and the reference light for recording are projected upon an optical information recording medium (1) such that they converge in different positions, and information is recorded in the hologram layer (3) in the form of an interference pattern as a result of interference between the information light reflected by a reflecting film (5) and the reference light for recording.

Abstract: A spatial light modulator (SLM) 101 has a multiplicity of pixels 101a arranged in a lattice form for selecting a transmission state (on) and a blocking state (off) of light on each pixel thereby spatially modulating light intensity. The spatial light modulator 101 has a light transmissivity distribution over whole pixels is set such that a light transmissivity is lower at and around a center and increased with increasing distance from the center.

Abstract: In a method of producing video screen holograms, a real video screen is illuminated by means of a narrowband light for producing a hologram of the real video screen. A plurality of individual recordings is carried out, each covering only a partial area of the real video screen being imaged in the hologram. The individual recordings take place, for example, by means of a scanning pulsed laser beam. The individual recordings are assembled to form the video screen hologram of the entire video screen. A recording device for this purpose comprises a scanning device for guiding the light radiation over the video screen and a light source which generates pulsed light radiation. The light source is, for example, a laser system with a pulsed q-switched oscillator and with an optical parametric oscillator.

Abstract: The present invention provides a two-beam interference exposure system that can be simply adjusted by rotating only one mirror. By placing a half-wave plate in one of the interference arms and precisely scanning the relative fiber position, the present invention can expose true apodized fiber Bragg gratings in a single scan by simultaneously rotating the angle of the half-wave plate. By rotationally switching the fast and slow axes of the half-wave plate, the present invention can also expose n-phase-shifted fiber grating by the same system.

Abstract: A method for monitoring diffraction while recording a hologram includes: generating a source beam; generating a data beam by projecting a first component of the source beam through a data source, the data beam having a first polarization; generating a reference beam by adjusting a polarization of a second component of the source beam to provide a second polarization; recording a hologram in a holographic medium from an interference between the data beam and the reference beam; and measuring an offset component in an output arm of the data beam.

Abstract: A single method and apparatus for producing many of the most common types of hologram from digital data is disclosed. The data are generated entirely by a computer as a 3-D (animated) model or from multiple 2-D camera images taken of a real 3-D (moving) object or scene from a plurality of different camera positions. The data are digitally processed and displayed on a small high resolution spatial light modulator (SLM). A compact low energy pulsed laser, is used to record composite holograms. The present invention permits the creation of restricted or full parallax master transmission or reflection type composite holograms, known as H1 holograms, that can be copied using traditional methods. Alternatively the same invention and apparatus permits the direct writing of hologram without the need to pass through the intermediate stage of the H1 transmission hologram.

Abstract: A method of producing, by one hologram original plate, hologram tape accommodating a huge number of prepaid cards having mutually different specific codes. The method of producing a hologram comprises the steps of forming an oblong two-dimensional image having random numbers in a bar-code form, preparing a hologram original image based on the two-dimensional image, winding the hologram original image around the surface of a drum(110), preparing a drum-like hologram original plate(101) having minute irregularities corresponding fringes formed on the surface of the drum(110) by an etching technique, rotating the original plate(101) on the surface of a blank sheet(120) to repeatedly transfer the minute irregular hologram original image(111) on the surface of the original plate(101) onto the blank sheet(120), cutting the original image(111)-transferred blank sheet(120) into specified lengths, cutting the blank sheet(120) into length that does not exactly divide a circumferential length of the original plate(101).

Abstract: The invention provides systems and methods for generating and displaying computational holographic stereograms having a hologram surface and a spatially distinct image surface. A three-dimensional object or scene is captured or synthesized as a stack of views. The holographic stereogram is computed by obtaining a diffractive fringe vector e and a pixel slice v through the stack of views, and generating the holopixel representation f=ev. The holographic stereogram is displayed using one or more image surfaces that are spatially distinct from the hologram surface. the surfaces can be any two-dimensional structures defined on a three-dimensional space, including, but not limited to planar, cylindrical, spherical, or other surfaces. The holographic stereograms are adjustable through variations in an image surface depth, an image surface resolution, a number of image surfaces, and a scene parallax resolution.

Abstract: A holographic storage apparatus for recording data in a holographic medium includes at least one light source for generating a reference beam and a signal beam. The reference beam is preferably a phase beam of unchanging phase content. The apparatus also includes a holographic medium placed in a path of the reference beam and a path of the signal beam. The holographic medium has a first face and both the reference beam and the signal beam enter the holographic medium through the first face. The holographic medium also includes a data reflective surface. The reference beam and the signal beam interfere in the holographic medium to create a hologram only after at least one of the reference beam and the signal beam have reflected off of the data reflective surface.

Abstract: An optical head comprises an integrated unit for recording and reproducing page data on a reflective recording medium, wherein the integrated unit includes recording and reproducing units each corresponding to a bit of data of the page data, wherein each of the recording and reproducing units has a light emitter for emitting an object beam and a reference beam, an optical switch for transmitting or blocking the object beam, and a detector. Each of the recording and reproducing units records a bit of data corresponding to a state indicating whether or not a hologram has been formed and reproduces a bit of data corresponding to a state indicating whether or not a reference beam has been received by the light receiver when a reference beam is emitted to a recording position. The integrated unit of the optical head records and reproduces page data on a recording medium by recording and reproducing bit data on the recording medium by each of the recording and reproducing units.

Abstract: A fiber Bragg grating may be written at an arbitrary wavelength without extensive recalibration or reconfiguration of the writing equipment in some embodiments. A pair of writing beams may be used to expose the fiber. The crossing angles of the writing beams may be adjusted.

Abstract: A description is provided of an optical information recording and reproducing apparatus having a volume holographic memory. The apparatus is capable of recording an interference pattern in the volume holographic memory in high density and can be made small-sized.

Abstract: A distributed system for producing holographic stereograms (holograms). A data acquisition station is typically remote from image processing, printing, and replicating stations. The data acquisition station is designed to maximize customer convenience, and may be the customer's own personal computer. The data acquisition station is further designed to accept a wide variety of source data and to perform whatever processing is required to deliver image data to the image processing station in an acceptable format. The data acquisition station further has processing capability to display preview images, which may be assembled by programming executing at the data acquisition station or downloaded from a server.

Abstract: In a holographic digital data storage system, holographic page data has at least two concentric patterns with the optical information arranged within an outermost pattern of at least two concentric patterns. Since at least two concentric patterns in the holographic page data are deformed into at least two elliptic patterns in the diffracted beam caused by irradiation of the reference beam, at least two elliptic patterns are extracted from the diffracted beam and then at least two elliptic patterns are estimated to generate at least two estimated concentric patterns. A compensated vector between said at least two elliptic patterns and said at least two estimated concentric patterns is used to reconstruct the optical information from the diffracted beam.

Abstract: In accordance with teachings of the present invention, a device accomplishes the task of reducing or preventing reflections of the reference beam off a diffuser from striking the holographic recording material. First, the device absorbs a large percentage of the reference beam power so that portion of the reference beam never reaches the diffuser. Second, the device blocks the small amount of reference beam that is incident on the diffuser and reflects back toward the film. Thus, the proposed device operates as an absorber-blocker (AB) for the reference beam.

Abstract: A simple, compact optical system is provided that includes a transmissive optical element and a HOE but that nevertheless does not require an extra optical element for the correction of chromatic aberration. The HOE is designed to have diffractive efficiency for each of R, G, and B light beams and have different focal lengths for those light beams so as to correct the longitudinal chromatic aberration produced by a rectangular parallelepiped prism. This eliminates the need for an extra means for correcting the chromatic aberration produced by the prism. The HOE may be designed to exhibit different angles of diffraction for the R, G, and B light beams so as to correct the chromatic aberration produced perpendicularly to the optical axis by a wedge-shaped prism.

Abstract: A method and system of interference lithography (also known as interferometric lithography or holographic lithography) which utilizes phase-locked, scanning beams (so-called scanning beam interference lithography, or SBIL). The invention utilizes a high-precision stage that moves a substrate under overlapped and interfering pairs of coherent beams. The overlapped beams interfere, generating fringes, which form a pattern “brush” for subsequent writing of periodic and quasi-periodic patterns on the substrate. The phase of the fringes in the overlapped region is phase-locked to the motion of the precision stage. The invention includes methods for forming, overlapping, and phase-locking interfering pairs of beams on a variety of substrates; methods for measuring and controlling the period, phase, and angular orientation of fringes generated by the overlapping beams; and methods for measuring and controlling the effects of stage mechanical and thermal drift and other disturbances during the writing process.

Abstract: This invention discloses a method of producing, in a solid transparent material (3), a hologram of an object; the method includes the steps of: developing a three-dimensional mathematical model of an electro-magnetic field emanating from the object, the field producing an image of the object; computing a corresponding three-dimensional set of points, light scattered from which reconstructs the field; and focusing a pulsed laser beam into the solid transparent material onto each of the points sequentially, the beam being capable, when focused, of causing optical breakdown in the solid transparent material.

Abstract: Apparatus for generating a dynamic image includes a laser light source for generating a coherent beam of light; optics for separating the light beam into a reference beam and an object beam; a lenslet light modulator, including an array of lenslets and a pixilated light modulator having a plurality of light modulating pixels associated with each lenslet in the array, the lenslet light modulator being located to modulate the object beam; image processing electronics for driving the lenslet light modulator with dynamic image data to produce a dynamic image at a recording plane; and optics for interfering the dynamic image and the reference beam at the recording plane to produce a hologram of the dynamic image in a holographic recording medium located in the recording plane.

Abstract: An image exposure recorder for exposure-recording a holographic stereogram image or a hologram image on a recording medium for hologram. The recorder has an inverse correction system for rotating the polarization plane of a reference light (R) by means of a half-wave plate (11), directing the reference light (R) to a hologram recording medium (3), and measuring the intensity of a part of the reference light (R) transmitted through a polarizer (12) out of the reference light (R) transmitted through a part of the area of the hologram recording medium by means of a photodetector (13). In the inverse correction system, the angle of rotation of the half-wave plate is so determined that the intensity of the reference light (R) determined by the photodetector may be minimum or maximum.

Abstract: In a hologram recording method for forming a plurality of areas of a refractive index light interference pattern of a coherent signal light beam in accordance with information data within a recording medium having a shape of parallel flat plates, the signal light beam and the recording reference light beam cross each other within the recording medium, and a gate light beam having a second wavelength for revealing recording sensitivity of the recording medium is simultaneously irradiated to the recording medium so as to pass through a portion of the recording reference light beam and demarcate a volume smaller than that of this crossing portion.

Abstract: Holographic methods for recording fast movies whose speed is limited by the laser pulse duration if the recording material has sufficient sensitivity to reliably record a frame of the fast event with a single pulse. The method we describe uses the selectivity of multiplexed holograms to resolve frames that are recorded with adjacent pulses. Specially designed pulse generators are used to generate the signal and reference pulse trains. We experimentally demonstrate the system by making movies of laser induced shock waves with a temporal resolution of 5.9 ns, limited by the pulse width of the Q-switched Nd:YAG laser used in the experiments.

Abstract: Certain types of holographic recording materials can be used to updateably record holographic stereograms formed when fringe patterns are generated through interference of an object laser beam containing image information with a reference laser beam. In this manner, calculation of fringe patterns is avoided, and instead perspective information is computed for a scene or object to be displayed, the information is downloaded to display hardware such as a spatial light modulator, and fringe patterns are subsequently generated through interference of an object laser beam containing this information with a reference laser beam in the classic hologram recording scheme. Previously recorded holographic stereograms or component hogels are updated by erasing the stereograms or component hogels and recording updated stereograms or component hogels, or by recording updated stereograms or component hogels in a separate portion of the holographic recording material.

Abstract: Angle of incidence of reproducing light with respect to a hologram or a holographic stereogram is adjusted so that a reproduced image can be repetitively viewed without requiring the viewer to move his or her viewpoint. The components of the image reproducing apparatus can be roughly classified into a power supply unit equipped with a power supply for generating a driving power and various types of electric circuits, a light source unit equipped with light emitting diodes and the like, a supporting unit for supporting the light source unit, and a holographic stereogram display unit for holding the holographic stereogram and displaying an image. In this image reproducing apparatus, the light source unit is swingably or turnably moved repetitively with respect to the holographic stereogram so that the reproducing light has angle of incidence changed on the holographic stereogram, thus allowing change of viewed image.

Abstract: A method of fabricating a hologram screen having a large visual range and a hologram imaging apparatus used for the particular method of fabricating the hologram screen are disclosed. A plurality of mirrors (3) extended toward a plurality of photosensitive members (5) are arranged at a plurality of end portions (21), respectively, of a light diffuser (2). At least a reference beam (41) and object beams (42) passed through the light diffuser (2) are radiated on a plurality of the photosensitive members (5) individually thereby to form a plurality of holograms. These holograms are integrated with each other by being arranged two-dimensionally thereby to fabricate a hologram screen. Among the mirrors (3), a reference beam-side mirror (31) arranged nearer to the light source of the reference beams (41) is extended from the light diffuser (2) by a length varied with the position of the photosensitive member (5) to be exposed.

Abstract: In a storing mode of an apparatus for storing and retrieving a sequence of digital page data, a first/second complex reference beam and a modulated signal beam converge on a storing location to generate a sequence of first/second interference patterns to be sequentially stored on a holographic medium. A shift selectivity of the first complex reference beam is larger than that of the second complex reference beam so that the second interference pattern is used as a servo pattern to sequentially determine where the first interference patterns have been stored.

Abstract: In a storing mode of an apparatus for sequentially storing and retrieving digital page data, a first and second complex reference beams and a modulated and second signal beams converge on a first/second location to generate a sequence of first and second interference patterns to be sequentially stored on a holographic medium. A shift selectivity of the first complex reference beam is larger than that of the second complex reference beam so that the second interference pattern is used as a servo pattern to sequentially determine where the first interference patterns have been stored.