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5903390 |
Two port nonlinear joint transform correlator
An all optical photorefractive holographic joint transform correlator provides a first correlation plane output port using two-beam coupling, and a second correlation plane output port employing...
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5887090 |
Optical network
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...
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5883741 |
Optical head device and birefringent diffraction grating polarizer and polarizing hologram element used therein
An optical head device uses a birefringent diffraction grating polarizer configured in a reflection type. The device includes a polarizing hologram element which reflects the light from a light...
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5864412 |
Multiphoton photorefractive holographic recording media
A multiphoton photorefractive holographic recording material includes an electro-optic host material doped with at least one lanthanide.
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5859713 |
Imaging in a scattering medium using photon density waves
Image derogating optical noise due to light scattering of an object under examination, embedded in a light scattering medium, is substantially reduced by passing a modulated signal laser beam...
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5847851 |
Double-doped BaTiO.sub.3 crystal for holographic storage
A new photorefractive material comprises BaTiO 3 double-doped with two dopant species, both of which have at least two valence states, with one of the dopant species (e.g., cerium) having an...
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5844700 |
Spatio-angular multiplexing geometry for volume holographic storage
Partially overlapping holograms are stored in a cylindrical volume holographic storage medium capable of rotation about and translation along its longitudinal axis. The reference and signal beams...
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5822090 |
Utilization of ferroelectric domain screening for high capacity holographic memory
The present invention describes a method for high capacity holographic data storage in photorefractive crystals. A doped ferroelectric crystal is used as a data storage medium. Prior to the...
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5818614 |
Single-wavelength emission device
This device comprises an optical source emitting a single-wavelength light beam. An index grating has been recorded in a holographic device by the interference of two plane light beams, both being...
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5796498 |
Holographic imaging
A holographic imaging apparatus having a pulsed laser light source for generating an object beam and a reference beam whereby an object, obscured by a diffusing medium, is illuminated by the object...
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5796096 |
Fabrication and applications of long-lifetime, holographic gratings in photorefractive materials
Substantial improvements in photorefractive device lifetimes are provided by control of electron migration which results in the decay of gratings in photorefractive materials due to diffusion and...
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5793504 |
Hybrid angular/spatial holographic multiplexer
A plurality of holograms are simultaneously angularly and spatially multiplexed within a storage medium by writing the holograms at different locations within the storage medium using reference and...
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5777760 |
Position feedback system for volume holographic storage media
A method of holographic recording in a photorefractive medium wherein stored holograms may be retrieved with maximum signal-to noise ratio (SNR) is disclosed. A plurality of servo blocks containing...
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5760902 |
Method and apparatus for producing an intensity contrast image from phase detail in transparent phase objects
A method and apparatus for producing images in which phase variation introduced by reflections from a transparent phase object are represented in interference generated phase contrast, and in which...
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5754318 |
Apparatus for parallel recording of holograms in a dynamic volume medium
Apparatus for the simultaneous parallel recording of holograms on a dynamic volume medium. Directed along a recording axis is a polychromatic source image which has multiple component images to be...
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5739929 |
Method and device for holographic storage
A two-photon process for writing to a holographic recording medium comprising a photorefractive material doped with an excitation dopant selected from rare earth ions and an ionization dopant...
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5729364 |
Ion and impurity concentration optimization in photorefractive media for dynamic and fixed holography
Ionic and impurity concentrations in a photorefractive holographic storage medium are optimized such that electronic and ionic Debye numbers match an expected grating wave number K, at fixing and...
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5717508 |
Method for dynamically refreshing angle-multiplexed holograms in photorefractive media
A method and system are disclosed for dynamically refreshing angle-multiplexed holograms stored in a photorefractive medium. In accordance with the invention the photorefractive medium is...
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5699175 |
Multiphoton photorefractive holographic recording media
A multiphoton photorefractive holographic recording material includes an electro-optic host material doped with at least one lanthanide.
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5698344 |
Two-step gated holographic recording in photorefractive materials using cw lasers
Ferroelectric materials are disclosed as reversible holographic recording media (25) for use in two-photon recording systems. The ferroelectric materials disclosed herein provide long-lived...
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5691829 |
Method for fixing optical information in crystals and for quasi-phase matching in frequency mixing
A method and apparatus for fixing images, holograms and domain gratings in crystals by application of an electric field on a crystal and simultaneous illumination of it with a light pattern. The...
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5684612 |
Method and system for maintaining and controlling the signal-to-noise ratio of hologams recorded in ferroelectric photorefractive materials
A hologram with a dynamically controlled diffraction efficiency and enhanced signal-to-noise ratio is recorded in ferroelectric photorefractive materials, such as strontium barium niobate (Sr x Ba...
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5684611 |
Photorefractive systems and methods
A new type of holographic recording in photorefractive crystals is disclosed, termed orthogonal data storage, in which counterpropagating, reflection mode holograms are wavelength multiplexed to...
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5665493 |
Gated recording of holograms using rare-earth doped ferroelectric materials
Rare earth doped ferroelectric materials are disclosed as reversible holographic recording medium (25) for use in two-photon recording systems. Such rare earth elements provide long-lived...
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5648856 |
Method for optically fixing holograms in photorefractive materials and a read/write memory based thereon
A method and read/write memory based thereon for storing phase holograms in a photorefractive crystalline material in which electric-field-mobile positive ions are associated with certain sites...
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5642210 |
Method for mitigating cross-talk in high-efficiency holograms
In a method for mitigating cross-talk in high-efficiency, angle-multiplexed holograms stored in photorefractive media, a plurality of uniformly low-efficiency holograms are first stored within a...
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5604634 |
All optical nonlinear joint fourier transform correlator
A fully parallel, self-aligning, nonlinear and all optical joint transform correlator utilizes a photorefractive four wave mixer positioned to record the joint transform spectrum interfering with a...
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5557431 |
Real-time compensated imaging system and method using a double-pumped phase-conjugate mirror
An adaptive optics imaging system uses a double pumped phase conjugate mirror (DPCM) to compensate for phase, amplitude or polarization aberrations imposed upon a multi-pixel object beam. A remote...
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5539542 |
Photorefractive device having an electro-optical material between two photoconductive materials
A photorefractive apparatus is exposed to a write beam or radiation for creating a system of interference fringes in the apparatus, as well as to a read beam or radiation which diffracts the system...
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5535024 |
Photorefractive holographic interference novelty filter
A novelty filter utilizes self-nulling and self-aligning of reflection and transmission phase conjugate beams. A photorefractive crystal is arranged so that the contributions to the phase conjugate...
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5528402 |
Addressable electrohologram employing electro-optic layer and patterned conductor between two electrodes
An electrically addressable wavefront-modulation device has a thin film of transparent conductive material finely patterned as a hologram in which individual fringe elements need not have...
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5508829 |
LTG AlGaAs non-linear optical material and devices fabricated therefrom
A light responsive device (10) has a body (12) that includes a matrix comprised of Group III-V material, the matrix having inclusions (14) comprised of a Group V material contained therein. The...
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5495101 |
Enhancement for broadband optical limiter with holographic grating
A passive broadband sensor protection and enhancement system and technique. ncident light is focused with a cylindrical lens on the optical axis into an intense light strip onto the input face of a...
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5493628 |
High density optically encoded information storage using second harmonic generation in silicate glasses
Multiple bits of information are stored in the frequency domain in a bulk glass using optically encoded χ (2) gratings. The information is read out by measuring a second harmonic generation (SHG)...
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5493444 |
Photorefractive two-beam coupling nonlinear joint transform correlator
An all-optical nonlinear joint transform correlator has been implemented for the first time without using a spatial light modulator and digital processing in the Fourier plane. The correlator...
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5491570 |
Methods and devices for using photorefractive materials at infrared wavelengths
A method of writing plane holographic gratings Bragg-matched for reflection in the infrared in a photorefractive material using shorter wavelength light through a face perpendicular to the grating...
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5440669 |
Photorefractive systems and methods
A new type of holographic recording in photorefractive crystals is disclosed, termed orthogonal data storage, in which counterpropagating, reflection mode holograms are wavelength multiplexed to...
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5383038 |
Holographic optical memory using semiconductor microcrystallite doped glasses and method using same
There is described a semiconductor microcrystallite doped glass that exhibits SHG, and a method of preparing, or encoding, a semiconductor microcrystallite doped glass by the simultaneous injection...
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5361148 |
Apparatus for photorefractive two beam coupling
The present invention relates to an improved process for producing photorefractive net gain two beam coupling utilizing polymeric materials.
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5337170 |
Quadratic optical processor for reducing multiplicative noise and other uses
A degenerate four-wave mixing arrangement employs a photorefractive crystal as a real time holographic recording medium to record a hologram of the noisy optical signal. The signal passes through...
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5335098 |
Fixing method for narrow bandwidth volume holograms in photorefractive materials
An improved method for storing permanent holographic gratings in photorefractive materials for use in narrow band filters such as the H 60 filter, as well as the filters themselves. The invention...
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5305123 |
Light controlled spatial and angular electromagnetic wave modulator
A 2D/3D optically controlled spatial and angular electromagnetic wave modulator is disclosed. The modulator of the present invention modulates the amplitude and direction of an electromagnetic wave...
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5283672 |
Holographic techniques for generating high resolution telescopic images
Holographic apparatus and methods are provided for generating high resolution telescopic images using low cost, small aperture lenses. Holographic media, such as photorefractive crystals, are used...
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5282067 |
Self-amplified optical pattern recognition system
A self amplifying optical pattern recognizer includes a geometric system configuration similar to that of a Vander Lugt holographic matched filter configuration with a photorefractive crystal...
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5276543 |
Optical signal equalizer for wavelength division multiplexed optical fiber systems
This invention disclosure describes the application of a polarization insensitive acoustically-tuned optical filter used in a multichannel WDM system to equalize variations in the power level of...
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5235439 |
Volume-holographic inner product processor
A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern...
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5198913 |
Apparatus for displaying three-dimensional image by using Pockels readout optical modulator
An apparatus for displaying a three-dimensional image of a plurality of tomographic images by storing pictorial information of a tomographic image in an image convering element, forming...
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5198912 |
Volume phase hologram with liquid crystal in microvoids between fringes
Composite holograms are disclosed wherein microvoids between the holographic interference fringes are filled with a liquid crystal. The diffraction efficiency and other holographic properties of...
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5191448 |
Photorefractive square law converter
A photorefractive device is provided for converting an image-bearing incoherent input beam to a high contrast coherent output beam the intensity of which varies as the square of the input intensity...
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5173790 |
Adaptive filter with correlation weighting structure
An adaptive filter having a correlation weighting structue having a single Bragg cell, acting as a tapped delay line and having an input and an output, the Bragg cell intensity modulating a write...
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