Abstract: A system for projecting images is provided having a group of diffractive phase plates each encoded with different image information which have phase shifts aligned to reconstruct visible images in a Fraunhofer diffraction region. The plates are arranged along a path, and may represent successive frames of animation. A light source illuminates the plates and provides, when multiple plates are illuminated, a composite image representing image information encoded in such multiple plates. This composite image is a coincident superposition of reconstructed images from the multiple plates. A mechanism is provided for moving the plates along their path such that images projected from the system in the Fraunhofer diffraction region represent the composite image from successively different illuminated multiple plates or the reconstructed image from a single plate. Both monochromatic and multi-color channel phase plates may be used in the system.

Abstract: Novel apparatus for simultaneous spatial modulation of a set of angularly multiplexed individually coherent but mutually incoherent optical beams is disclosed, comprising means for generating a set of two or more individually coherent beams that have at least one optical wavelength in common, pairwise, and are assured to be mutually incoherent, and means for directing the set of individually coherent but mutually incoherent beams to a spatial modulation means, such that a spatially overlapping group of individually coherent but mutually incoherent beams overlap spatially in at least one region of the spatial modulation means and are angularly multiplexed within the region. Such simultaneous spatial modulation is a key feature, for example, in highly multiplexed photonic interconnection, memory, and display systems with maximum optical throughput efficiency and minimum crosstalk, based on parallel incoherent/coherent double angularly multiplexed holographic recording and readout principles.

Abstract: The present invention makes it possible to reduce the size of an optical system for multiplex recording or reproduction of information utilizing holography.

Abstract: A holographic recording and reproducing apparatus preforms to record data on a recording medium and reproduce data from the recording medium. The recording medium is made of a photorefractive crystal having a parallel plate shape.

Abstract: An apparatus for use in contoured architectural milieus includes a contoured large screen display having a mounting means to which modular flat display tiles including, tiles of diverse or non-standard shapes and sizes are attached, each display tile having a plurality of optical fibers affixed behind the tile and communicating with a front surface of the tile.

Abstract: A spatial light modulator/demodulator and a hologram recording/reproducing apparatus permitting a reduction of size, for a photorefractive-material recording medium using the same. The hologram recording/reproducing apparatus has a reference light part for making a coherent recording reference light beam incident on a main surface of the recording medium, a part for making a coherent signal light beam modulated according to image data incident on the recording medium and intersect the recording reference light beam in an interior thereof, and generating a refractive index grating of a three-dimensional light interference pattern of the signal light beam and recording reference light beam, and a part for making a coherent reproducing reference light beam propagated coaxially and in a reverse direction to the recording reference light beam incident on the recording medium to cause a phase conjugate wave from the refractive index grating of the light interference pattern.

Abstract: The first reading beam identical to the first reference beam and the second reading beam conjugate to the second reference beam are simultaneously applied to a hologram recording medium 1, on which holograms 2 and 3 have been recorded. A hologram is formed by interference between the first beam reproduced from the first reading beam and the second reading beam. Another hologram is formed by interference between the second beam reproduced from the second reading beam and the first reading beam. These holograms are recorded and superposed on the original holograms 2 and 3, thereby reproducing the original holograms 2 and 3.

Abstract: Systems and methods for determining the position and classification of an object and which may provide signals that control deployment of an active restraint device, for example. Using a pulsed laser light beam from a laser source that is spread and preferably diffused to avoid ocular damage, an interference pattern is returned to a sensing module through a spectral filter. There it is optionally combined with a reference beam from the laser source, modified to emulate coherence length effects, and incident upon a phase transmission holographic template that may be segmented into regions for example. Each region of the holographic template contains Fourier transform images of occupant types. Behind the holographic template is a detector array that is sensitive to the laser light. An interference pattern derived from the object is convoluted or cross-correlated with the template. When an match occurs, a bright spot appears on the detector array.

Abstract: A holographic storage medium, a method of manufacturing the holographic storage medium and a holographic storage device incorporating the storage medium. In one embodiment, the holographic storage medium includes: (1) first and second spaced-apart substrates, the first substrate being plastic and (2) a photopolymer core located between said first and second substrates and having a coefficient of thermal expansion such that said first and second substrates and said photopolymer core cooperate to respond substantially isotropically to a change in temperature.

Abstract: An apodised refractive index grating is recorded in a photosensitive optical fibre by forming first and second component interference patterns with different pitches, that are recorded in the grating such as to result in apodisation. The component patterns (16, 17) are spatially in phase in a central region and move progressively out of phase towards the ends of the patterns. The patterns may be recorded sequentially or concurrently. The fibre may be stretched one or cyclically.

Abstract: The present invention concerns methods and devices for creating and printing variable size and variable resolution holographic stereograms and holographic optical elements using computer rendered images of three-dimensional computer models or using computer processed images. The present invention is an apparatus and method for printing one-step, full-color, full-parallax holographic stereograms utilizing a reference beam-steering system that allows a reference beam to expose a holographic recording material from different angles. More particularly, a coherent beam is split into object and reference beams. The object beam passes through an object beam unit in which a rendered image is displayed, while the reference beam passes through the reference beam-steering system. The object and reference beams interfere with each other at an elemental hologram on a holographic recording material.

Abstract: An improved optical correlator using a coherent light beam employs a method of adaptive alignment. A test pattern modulates an input spatial light modulator. The modulated beam propagates through passive transforming optical elements to a filter spatial light modulator, which is simultaneously modulated with an independently transformed frequency domain reference. The resulting correlation or coincidence of the optically transformed pattern with the independently transformed reference is processed to yield a feedback signal indicative of any optical misalignment of the optical correlator. The feedback signal drives a beam deflector to compensate by adjusting the path of the coherent beam, thereby improving and maintaining optical alignment of the correlator.

Abstract: High storage densities using a holographic system are achievable using a stratified medium while maintaining a relatively high selectivity upon reconstruction of the stored images. Such combination of high density and high selectivity is achievable by employing a stratified medium and a recording process where selectivity does not vary with recording thickness.

Abstract: A fiber optic display apparatus consists of a plurality of optical fibers which convey a projected image from an input, or first surface, to a display, or second surface, whose area is greater than or equal to that of the first surface, such that any image projected on to the first surface appears enlarged on the second surface. The second surface is comprised of tiles which attach to adjoining tiles by means of flexible tabs and pliable locator rods in such a fashion as to allow the second surface to follow general contours (e.g. concave or convex), while the optical fiber bundles from each tile are collected into a fixture to form the first planar surface. Because of the modular design of the display it can be assembled or disassembled rapidly.

Abstract: An optical add/drop filter is formed using a hologram which is tuned to a wavelength in an optical signal. The diffraction condition of the hologram may be varied to vary the in add or drop content.

Abstract: A simplified method is provided for recording identification information, such as a serial number or the like, in a hologram-recorded film simultaneously with hologram duplication. The method includes the steps of coupling a hologram recording film with a master hologram plate having a master hologram, the master hologram plate having a reflective area adjacent the master hologram; and directing laser beams towards the master hologram plate to induce interference between incident laser light and diffraction laser light from the master hologram in the recording film, at least some of the laser beams radiating the reflective area through a transmission type controllable display device to record a pattern in the hologram recording film corresponding to a pattern displayed at the transmission type controllable display device.

Abstract: A method and an apparatus capable of filtering based on desired spatial frequency characteristics without loss of Fourier spectrum frequency components, and of matched filtering of high recognition capability without losing functions of data recording and reconstruction as well as high-speed transmission and retrieval features and mass storage capacity characteristic of a holographic memory. Fourier transformed object light with 0° polarization of a target image is stored as a hologram using reference light having a spatial polarization distribution such that a daughter wavelet on scale m has 90° polarization. The hologram is retrieved using the Fourier transformed object light with 0° polarization. The hologram yields diffracted light in the form of a spatial frequency component which corresponds to scale m and is polarized 90° with respect to the other spatial frequency components. A polarizing element is used to extract only the spatial frequency component corresponding to scale m.

Abstract: Optical information processor and storage of pixelated data pattern in a Fourier plane of a lens as achieved by a plurality of optical elements operating with a spatial light modulator. A laser light source illuminates a data pattern with a wavefront that is created by a phase mask to effect a phase shift. The optical information can be effecitvely processed or stored, for instance, in a holographic data storage system. The holographic data storage system for storing a data array contains illuminated and dark regions including a multi-fold phase shift mask. This affects a linear and non-random shift of an image. The image is stored on a holographic storage medium. There is a spatial light modulator between the input location for the optical data and the storage medium. The phase shift is effected in the Fourier plane.

Abstract: A method for suppressing image speckles in a holographic screen is provided in which the screen is illuminated in the hologram in a plurality of individual steps, changing the recording parameters at each step. As a result, a holographic screen is obtained that produces a speckle-free image from a hologram recorded with lasers and then illuminated by a laser. Depending on the application, the object screen can be recorded as a reflection or transmission hologram.

Abstract: A method for the numerical reconstruction of digital holograms which allows simultaneously amplitude and quantitative phase contrast imaging. The reconstruction method computes the propagation of the field that would be diffracted by the hologram during a standard hologram reconstruction. The method requires the adjustment of several reconstruction parameters for the definition of a digital replica of the reference wave. When the set-up used for the hologram creation produces phase aberrations, the method includes a digital method for the correction of the phase aberrations. The phase contrast image is quantitative, meaning that the reconstructed phase distribution can be used for quantitative measurements. The method can be used to reconstruct a set of holograms taken in different conditions. The method can be used to reconstruct several images from a single hologram taken with more than one reference waves and/or more than one object waves.

Abstract: A phase-shift digital holographic apparatus shifts the phase of a reference wave by a phase shifting means, produces holographic image data by a holographic image pickup means having an image forming surface on which an object wave and the reference wave fall simultaneously, processes a plurality of holographic image data produced by the object wave and a plurality of reference waves of different phases determined by shifting the phase of the reference wave by the phase shifting means by an object wave calculating means to calculate phase data on the phase of the object wave and amplitude data on the amplitude of the object wave, and constitutes object wave data of the phase data on the phase of the object wave and the amplitude data on the amplitude of the object wave calculated by the object wave calculating means by a reproduced image calculating means and subjects the object wave data to a predetermined transformation process to calculate a reproduced image.

Abstract: A technique for mapping working images to adjacently and continuously tiled subapertures having CGHs on a plate is disclosed with the result that the entirety of a working area of a plate is completely covered with working subapertures, these subapertures usually being rectangular. The design technique thereafter determines a phase function which approximately maps desired regions on each subaperture from portions of the working image in the workpiece plane. Steps in the process include first a determination of the size and shape of subapertures representing each feature. Second, a determination of the geometric transformation for each feature is made. Thereafter, backpropagation or other refinement to create the desired intensity profile at the workpiece is made.

Abstract: An improved process for holography is provided, in which the reference beam used for storage and readout has a correlated phase content. In particular, it was found that reference beams having random phase content limited the attainable storage density and the accuracy of readout of stored holograms due to uncontrolled fluctuations in the correlation selectivity. By contrast, a reference beam having correlated phase content provides accurate shift selectivity, the ability to tailor the reference beam spectrum to minimize crosstalk between neighboring holograms, and mitigation of limitations inherent in the holographic system or holographic medium. Improved storage density and readout accuracy are thereby attained.

Abstract: A system and method for controlling the selectivity function in a holographic memory system that permits more rapid location and retrieval of holographically stored data. The system and method direct a reference beam through a filter such as, for example, an aperture, to bandwidth limit the beam before the beam illuminates a holographic optical element having stored therein a hologram of a reference beam.

Abstract: A holographic storage system implements both a rotational and an angular multiplexings in combination. The system comprises a light source, a pair of wedge prisms, a beam splitter, a first, a second, a third and a parabolic mirrors, a SLM(spatial light modulator) and a storage medium. In the system, a light beam emitted from the light source is split into a reference and a signal beams by the beam splitter. The signal beam reflected by the first mirror to the SLM which modulates data in the firm of pages. The modulated signal beam falls into the storage medium, while the reference beam is reflected by the second mirror to the wedge prisms which deflect the reference beam to an arbitrary position on the third mirror. The deflected reference beam is reflected onto the parabolic mirror by the third mirror. The deflected reference beam is converged onto the storage medium by the parabolic mirror.

Abstract: A synthetic aperture system for producing a non-periodic pattern in a region of overlap. The system includes a source of electromagnetic radiation producing a plurality of electromagnetic beams, a plurality of beam controllers positioned to receive a respective one of the plurality of electromagnetic beams and direct the respective electromagnetic beam into the region of overlap; and a system controller in electrical communication with each of the plurality of the beam controllers. Each beam controller controls at least one of the phase, amplitude and polarization of a respective one of the plurality of electromagnetic beams in response to control signals from the system controller. The result is a non-periodic pattern formed within the region of overlap by the interference of a plurality of electromagnetic beams in response to the control signals from the system controller.The invention also relates to a method for producing a non-periodic pattern in a region of overlap.

Abstract: Apparatus is provided for the readout, and in certain applications the display, of information stored within incoherent/coherent double angularly multiplexed volume holographic optical elements. Such multiplexed volume holographic optical elements are based on parallel incoherent/coherent double angularly multiplexed volume holographic recording and readout principles, and are designed to exhibit maximum optical throughput efficiency and minimum crosstalk. Applications for this novel holographic readout apparatus, when used in conjunction with the aforementioned incoherent/coherent double angularly multiplexed volume holographic optical elements, include photonic interconnections for neural networks, telecommunications switching, and digital computing; optical information processors and optical memories; and optical display systems.

Abstract: A holographic storage and retrieval system for use in co-propagating or counter-propagating geometries having a common optical relay for guiding a signal beam and a reference beam along a common optical axis to a holographic medium to write a hologram therein. The optical relay has an object region imaging quality such that at least 65% and preferably at least 80% of the nominal luminous energy from object pixels is encompassed or "ensquared" by the corresponding image pixels. Additionally, the optical relay has a high total numerical aperture (N.A.) of about 0.83, a pixel N.A. of approximately 0.04 for the signal beam. The system of the invention can be used with holographic storage media in the form of disks, tapes or bulk holographic crystals.

Abstract: A holographic memory device includes: a hologram memory part for information recording by using a reference beam and an object beam, the hologram memory part having a plurality of cells; a first optical path modifying part having a fine adjustment element that adjusts the reference beam's path so as to be incident on the hologram memory part at a specific angle for information recording and reconstructing, and that adjusts the reference beam's path so as to be incident on the hologram memory part at a desired angle for information reconstructing when an angle of incidence of reference beam for information reconstructing doesn't coincide with that of reference beam for information recording; and a second optical path modifying part that adjusts the object beam's path so as to be incident on the hologram memory part for information recording.

Abstract: A volume holographic memory-based optical information-recording/reproducing apparatus is capable of enhancing density of spatial multiple recording. A recording medium is mounted in the apparatus for recording a three-dimensional optical interference pattern formed by at least two coherent light beams as spatial changes in refractive index of the recording medium. A signal beam optical system supplies a coherent signal beam to the recording medium through a Fourier transform lens. A reference beam optical system supplies a coherent reference beam to the recording medium. The reference beam is caused to intersect with the signal beam within the recording medium and an angle of intersection between the reference beam and the signal beam is changed. Diffracted light of the reference beam diffracted from the recording medium is detected.

Abstract: An architecture for holographic data storage and processing integrates multifunctional silicon-based optoelectronic devices, rewritable holographic material, optical devices and other electro-optical elements in compact and high-performance systems. A dynamic hologram refresher based on optoelectronic integrated circuits has a smart pixel structure including an electrically addressed SLM to write a new data page, a thresholding detector array for readout, and a memory to latch the data from the detector to the modulator in each pixel. In particular, conjugate reconstruction is used in combination with the dynamic hologram refresher to retrieve data from volume multiplexed holograms in the rewritable holographic material.

Abstract: An optical storage system, which includes a temporary buffer and an optical storage medium, allows the practical combination of phase-conjugation and hologram multiplexing. The temporary buffer receives an object light beam and a first reference light beam, and records a first hologram at an intersection of the object light beam and the first reference light beam. The temporary buffer then receives a second reference light beam that is phase-conjugate to the first reference light beam and that illuminates the first hologram, thereby generating a phase-conjugate object light beam. The optical storage medium receives the phase-conjugate object light beam and a third multiplexed reference light beam, and records a second hologram for long-term storage at an intersection of the phase-conjugate object light beam and the third reference light beam.

Abstract: A programmable hologram generator comprises a layered structure of a pixelated VLSI chip, a reflective ferroelectric liquid crystal that is physically disposed on the VLSI chip, and a photorefractive crystal that is physically disposed on the liquid crystal. The VLSI chip is controlled by a computer wherein holograms are digitally stored. The reflective state of the individual pixel areas of the liquid crystal are controlled or selected by this computer control of the VLSI chip. A desired hologram is written into the photorefractive crystal by a reference beam that illuminates the photorefractive crystal, and by an illumination beam that is reflected from the selected pixels of the liquid crystal and thereafter interferes with the reference beam. The hologram that is written into the photorefractive crystal is a function of the control of the reflective state of the pixels of the liquid crystal, as this reflective state is in turn controlled by the pixels of the VLSI chip.

Abstract: The present invention is a method for optical data storage which enhances the contrast between ON and OFF pixels. The method comprises writing a two-dimensional image comprising a plurality of pixels into a recording medium with the exposure of individual ON pixels during the recording of the image. The ON pixels are then switched off and OFF pixels are switched on, and the phase of either the object beam or reference beam is changed. The process results in subtraction of residual signal from the OFF pixels.

Abstract: Embodiments of the invention include an off-axis amplitude and phase encoding optical system, apparatus and method of storage in which a holographic optical element (HOE) is used advantageously to reconstruct optical elements typically used to phaseencode an object beam emanating from a spatial light modulator (SLM). The optical system includes a spatial light modulator (SLM) such as a digital micro-mirror device (DMD), a data storage device such as a holographic memory cell (HMC), and the holographic optical element (HOE) for duplicating the phase-encoding functions typically performed on an object beam emanating from the SLM prior to alignment with the holographic memory cell (HMC). Conventionally, a phase mask along with one or more optical elements comprising a four-F lens system typically are needed to phase encode the amplitude-encoded light pattern that propagates from the SLM.

Abstract: The present invention is a holographic reconstruction device for reconstructing successive holograms previously recorded by a recording reference beam in a recording medium, each previously recorded successive hologram being spaced apart a recording displacement. The recording reference beam has a recording wavelength in the range where the recording medium is photosensitive and a recording propagation angle. The device comprises a reconstruction mechanism having a reconstruction reference beam with a reconstruction wavelength in the range where the recording medium is relatively photo-insensitive and a reconstruction propagation angle. The reconstruction reference beam is provided onto the recording medium. Also, a succession of relative displacements in the recording medium is produced and each of the displacements are equal to the distance of the recording displacements with which the holograms were previously recorded.

Abstract: A method and an apparatus for increasing detection signal-to-noise ratio of a holographic image by compensating for noise characteristics of a holographic storage medium are disclosed.

Abstract: An optical demultiplexing apparatus is capable of spatially separating a multiplexed optical signal into two or more optical wavelength signals thereof. An input multiplexed optical signal present on a first plane is imaged through a color-selective grating plane to a second plane. The color-selective grating has a nonlinear change of diffraction characteristics as a function of incident wavelength to provide substantial spatial separation in the second plane between bands of wavelengths proximate to the two or more optical wavelength signals. In another embodiment, the apparatus uses a polarization-selective grating to spatially separate a polarization-multiplexed optical signal into two substantial spatially separated optical polarization signals. In other embodiments, the optical apparatus may be used as an optical signal multiplexer, splitter, or combiner.

Abstract: An architecture for holographic data storage and processing integrates multifunctional silicon-based optoelectronic devices, rewritable holographic material, optical devices and other electro-optical elements in compact and high-performance systems. A dynamic hologram refresher based on optoelectronic integrated circuits has a smart pixel structure including an electrically addressed SLM to write a new data page, a thresholding detector array for readout, and a memory to latch the data from the detector to the modulator in each pixel. In particular, conjugate reconstruction is used in combination with the dynamic hologram refresher to retrieve data from volume multiplexed holograms in the rewritable holographic material.

Abstract: A display includes a plurality of individually electrically controllable pixels. Each pixel has a layer of light controlling medium extending over a predetermined area of the pixel. The light controlling medium is responsive to electrical fields directed through the area of the light controlling medium for controlling the light passing through the pixel as a predetermined function of the magnitude of the electric field. Each pixel has an electric field directing arrangement for directing an electric field through the layer of light controlling medium of the pixel. The electric field for each pixel is controllably variable over the area of the light controlling medium of the pixel such that the light passing through the area of the light controlling medium of the pixel is controlled in a manner that varies over the area of the pixel depending on the variable electric field.

Abstract: The invention is embodied in a method of recording successive holograms in a recording medium, using at least a fan of M waves along at least a first axis with a separation angle between adjacent waves and directing the fan of M waves as a reference beam along a reference beam path onto the recording medium, successively modulating a wave with a succession of images to produce a succession of signal beams along a signal beam path lying at a propagation angle relative to the reference beam path so that the signal and reference beams intersect at abeam intersection lying within the medium, the beam intersection having a size corresponding to beam areas of the reference and signal beams, producing a succession of relative displacements in a direction parallel to the first axis between the recording medium and the beam intersection of the signal and reference beam paths in synchronism with the succession of signal beams, each of the displacements being less than the size of the intersection whereby to record succ

Abstract: Selection of individual holograms during read-out of a multiplexed array depends upon varying relative position of the recording medium in the direction orthogonal to the medium surface.

Abstract: An encryption method and apparatus for holographic data storage are disclosed. In a system using orthogonal phase-code multiplexing, data is encrypted by modulating the reference beam using an encryption key K represented by a unitary operator. In practice, the encryption key K corresponds to a diffuser or other phase-modulating element placed in the reference beam path, or to shuffling the correspondence between the codes of an orthogonal phase function and the corresponding pixels of a phase spatial light modulator. Because of the lack of Bragg selectivity in the vertical direction, the phase functions used for phase-code multiplexing are preferably one dimensional. Such phase functions can be one-dimensional Walsh functions. The encryption method preserves the orthogonality of reference beams, and thus does not lead to a degradation in crosstalk performance.

Abstract: Method and apparatus are provided for a general purpose photonic computer. A data signal is input through an encoder to encode such signal with an instruction. The encoded signal is transmitted by means of a laser beam to an input buffer where it interferes with a reference beam so as to form an interference pattern therein as a hologram, IPH. A read beam is directed through the IPH and through a decoder which reads the instruction as having, e.g. an OP Code, data source and destination. The decoded instruction is forwarded on the read beam to ALU spin media which respond to the instruction by flipping spins between two energy levels, in one or more sequences of data patterns which are read or measured by one or more sensors. Such sensors can be RF, microwave or optical sensors, which sensors output Radix=2 or digital data signals for, e.g. storage, display or further processing as desired.

Abstract: An optical device for generating a signal based on a distance of an object from the optical device. The optical device includes a first polarizer, a birefringent crystal positioned optically downstream from the first polarizer, and a second polarizer arranged optically downstream from the birefringent crystal. The second polarizer creates a pair of interferograms by adjusting a phase of the light. Two outputs are generated by separately integrating an amount of light of at least a part of each of the pair of interferograms. Finally, the two outputs are combined such that the signal, depending only on the distance between the object and the optical system, is obtained.

Abstract: A method for the production of holograms proof against copying and imitation possessing authenticity features, which are copies of a master hologram. In accordance with the invention as a master hologram a hologram of a randomly structured optical element, as for example a diffusion plate, which constitutes the authenticity feature, is recorded and each hologram copy produced from the master hologram is provided with a layer having at least one layer with a color succession and/or the hologram copy produced on a thick light sensitive layer is caused to shrink or to expand.

Abstract: Molded block optics system (10) writes and reads data from an optical storage medium and includes first molded optics block (12) for receiving reference beam (60) and original object beam (46) that contains a predetermined data set. First molded optics block (12) includes reflective surfaces (18, 20, 22, and 24) and spatial light modulator (50). Reflective surfaces (18, 20, and 24) include reference beam surfaces (24) and object beam surfaces (18, 20, and 22). Reference beam surfaces (24) direct reference beam (60) to optical storage medium (16) at predetermined location (54). Spatial light modulator (50) modulates object beam (46) and directs modulated object beam (46) to predetermined location (54). Reference beam (60) and object beam (46) form an interference pattern that writes data on optical storage medium (16). First molded optics block (12) also directs reference beam (60) to optical storage medium (16) for generating reconstructed object beam (64).

Abstract: A holographic recording apparatus includes first and second light sources for respectively generating first and second light beams. A mask is located in front of a hologram recording material and has an aperture. Interference fringes are recorded in a hologram cell on the hologram recording material corresponding to the aperture. A movement mechanism supports the hologram recording material masked by the mask and relatively moves the hologram recording material with respect to the mask in predetermined directions so that an interference pattern is formed in an area on the hologram recording material. A spatial frequency changing mechanism changes incident angles of the first and second light beams with respect to the mask.

Abstract: An optical interconnection network in which more than one communication can ccur at any give time is disclosed. The interconnection network can form part of a parallel computer, a fiber optic switching network, a massive video or data server or an asynchronous transfer mode (ATM) network. The network includes transmission network elements, reception network elements and a holographic storage element. The holographic storage element is located equidistant form all the transmission and reception network elements and stores therein a multiplicity of holograms. Each volume hologram is responsive to a different angle of incidence of wavelength.

Abstract: Systems and methods for steering an optical path to gain access to data locations in a holographic memory cell (HMC). One of the systems includes: (1) a refractive element that receives a complex, spatially-modulated incident beam of light, (2) first and second reflective elements locatable to receive and reflect the incident beam in a Fresnel region thereof and (3) a reflective element steering mechanism, coupled to the first and second reflective elements, that moves the first and second reflective elements in tandem to steer the incident beam with respect to the HMC thereby to cause the incident beam to illuminate a location on the HMC that is a function of a movement of the first and second reflective elements.