Abstract: A method and apparatus for holographic storage with combined orthogonal phase codes and random phase codes are provided in which a reference beam (18) is encoded with a combination orthogonal phase code and random phase code by a phase encoder (28). A data pattern is imposed on an object beam (20) by pattern encoder (38). Both the reference beam (18) and the object beam (20) are directed to a particular stack site on a storage medium (32).

Abstract: The fiber optic-based correlating and sensing system (the System) utilizes length of optical fiber through which the object beam travels prior to being incident on the holographic plate. First, a matched filter is created on the holographic plate of the initial condition of the environment. Then when the plate is re-placed in its original position in the System and the reference beam is blocked from reaching the plate, a correlation peak appears as the object beam passes through the holographic plate. To use the System as a correlator, the object beam is transmitted through an input scene prior to its travel through the optical fiber. The changes in the input scene from the initial scene causes broadening of the shape of and degradation of intensity of the correlation peak. To use the System as a sensor, the object beam travels through the optical fiber acquiring information regarding the environment surrounding the fiber, such as pressure, temperature, sound, electric and magnetic fields.

Abstract: 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 reference beam together with a phase conjugator which directs a readout beam at the four wave mixer. The signal readout of the mixer is Fourier transformed and can be recorded upon an image sensor to detect the correlation spots indicating the degree of similarity of the two input images.

Abstract: Limiting quadratic processing and compansion in photorefractive two beam coupling is disclosed. Two-beam coupling in photorefractive barium titanate employs the imaged intensity of the signal to amplify the reference beam while maintaining the phase of the reference beam. The phase distorted signal beam is converted to that of the controlled phase of the reference beam. The high pump limit of amplification in this two-beam coupling device produces an amplitude compressed output to reduce multiplicative noise. Lost contrast of the image is thereafter restored. Beam clean-up of a non-intelligence bearing beam can be carried out by a similar process; a low pass filter consisting of a pinhole plate can be used in place of the second photorefractive crystal in the Fourier plane and only the planar wavefront portion will pass through the pinhole and may be collimated by a lens to provide a cleaned planar output beam.

Abstract: The invention provides an optical device with high light utilization efficiency that is capable of scribing patterns on curved surfaces, as well as flat surfaces, using a liquid crystal spatial light modulator. The invention offers an optical device with high light utilization efficiency and that is capable of three-dimensional formation of curved surfaces using a liquid crystal spatial light modulator. Additionally, the invention offers a widely applicable optical processing system that mounts these optical devices on robots. The invention includes at least a coherent light source, a liquid crystal spatial light modulator for controlling the wavefront of the light from the coherent light source, and a means that records the complex amplitude distribution on the liquid crystal spatial light modulator.

Abstract: A disk-based holographic storage media includes a disk fabricated from a holographic storage media. A plurality of holographic storage regions are defined within the storage media such that pages of holographic data can be stored therein in the form of an interference grating. A Read/Write head is provided for containing the optics necessary to read information from the holographic storage region and write information thereto. The Read/Write head moves along the radial direction of the disk with the disk stepped by a motor to discrete angular positions, comprising the address of the storage region along with radial positioning of the Read/Write head. Each of the storage regions is diamond-shaped and oriented such that the apexes thereof are oriented along a common radial column line. Adjacent columns have the storage regions disposed in alternating rows or tracks. This allows for a higher packing density.

Abstract: A method and a viewing device for generation of selective visual effects. The method entails encoding a holographic optical transparency for generating pre-selected patterns of light when stimulated by appropriate sources of light and a structure to enable viewing through such a transparency. The viewing device contains a suitably encoded holographic optical transparency and a structure produced with semi-rigid material which allow viewing of the natural scene through the transparency with two eyes. The encoding of the transparencies causes all limited extent light sources in a scene to be replaced with pre-selected patterns of light while producing minimal distortion in the remainder of the scene.

Abstract: A serial-to-parallel and parallel-to-serial conversion apparatus and method are disclosed to convert optical pulse data into temporally multiplexed ultra-fast optical pulses, and vice versa, using Fourier holographic transform techniques. In a first embodiment, optical pattern data is converted from a serial temporal-domain optical input signal to an output signal having parallel bits by recording a spectral hologram of the pulse data and reading it out with a continuous-wave (cw) laser. In a second embodiment, signals representing input bits in parallel may be optically multiplexed in the time domain, so that a single optical fiber may carry such signals without the electronic processing necessary in conventional switching multiplexers.

Abstract: An optical signal processor which employs a coherent light source, two spatial light modulators and a beam splitter. Light is from the source is reflected from the beam splitter and sent to a first spatial light modulator, then sent through the beam splitter, a Fourier transform is performed and the transformed light is then reflected from the second spacial light modulator. The light form the second spacial light modulator is then inverse transformed and returned to the beam splitter where it is reflected to a readout detector. The signal read out is the correlation map between an input image from the first modulator and a filter image of the second modulator.

Abstract: A holographic storage assembly is provided which utilizes a large holographic storage media (36) disposed between two reflecting surfaces (40) and (42). An optics system (44) is disposed between the two reflecting surfaces (40) and (42) is operable to generate both a reference beam (58) and a data beam (50). The data beam (50) and reference beam (58) are generated on a virtual spot plane (100), which is then imaged from the surface of the reflecting surface (42) onto the much larger surface of the media (36). This is operable to record an interference grating at a storage location (56). During a playback operation, a reconstructed data beam (64) is generated and reflected from the surface of the mirror (40) onto a detector (68) in the deflector system (44).

Abstract: A tape cartridge (12) is provided for storing holographic recordings in a longitudinal holographic storage media tape (14). The tape (14) is comprised of a thin holographic storage media such as a photopolymer. A laser (54) is operable to generate a coherent light beam, which is then positioned on a given row of storage regions (42) on the surface of the tape (14). A positioning/angle multiplexing device (90) is operable to both position a reference beam (60) and a data beam (62) onto a select one of the storage regions in a given row on the surface of the tape (14). The tape (14) is incremented a row at a time for each scan operation wherein both the reference and the data beams during a Write operation, and only the reference beam during the playback operation, are moved along a given row. The spinning polygon mirror (56) is utilized to provide both positioning along a given row and angle multiplexing in a select storage region, with the optic system removing the angular information from the data beam (62).

Abstract: A modulator apparatus for modulating arrays of input data V.sub.in to be stored in a holographic recording medium is disclosed wherein the final output data array V.sub.out has frequent transitions from light to dark and from dark to light in either dimension across the data page and has the total amount of illuminated regions throughout the entire data page held constant. These two constraints are achieved by a first set of control arrays obtained from two fixed sets of m.times.n binary arrays {A.sub.0, A.sub.1, . . . , A.sub.n } and {B.sub.0, B.sub.1, . . . , B.sub.m } which in turn are obtained from fixed sets of binary control vectors {a.sub.0, a.sub.0, a.sub.1, . . . , a.sub.n }, {b.sub.0, b.sub.1, . . . , b.sub.m }, respectively. The control vectors a.sub.0, a.sub.1, . . . , a.sub.n any n+1 fixed elements of the inverse mapping, .phi. .sup.1 (C.sub.1), of the (t-2) error-correcting code C.sub.1 of length m. The control vectors b.sub.0, b.sub.1, . . . , b.sub.

Abstract: 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 templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus also includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.

Abstract: A package for a holographic storage media (10) is provided that utilizes a slide tray (43) for containing a plurality of slides (102). Each of the slides (102) is comprised of an opaque casing (110), which is operable to hold a sandwich structure (120). The sandwich structure (120) has a gripping mechanism (122) disposed on the edge thereof for allowing the structure (120) to be reciprocated within the jacket (110) for extraction thereof and reinsertion thereof. A gripping arm (156) is operable to attach to a gripping member (124) on a gripping mechanism (122) attached to the slide (102) to extract the slide (102) and place it into a holder (148). The holder (148) is then operable to receive the slide (102) and dispose it in a holographic storage system. The slide (102) can then be written to by interfering a data beam and a reference beam in a predetermined storage location (54) and then the slide again placed into the jacket (110).

Abstract: A method of verifying the authenticity of an object is disclosed preferrably employing a joint transform coherent optical processor. An unreadable and hence non-counterfeitable phase mask is coupled to the object and the optical processor compares the phase mask with a reference phase mask having the same phase code thereon. The processor produces a correlation spot having an intensity which exceeds a given level if the phase mask is genuine. A highly secure ID or credit card also carries a fingerprint bonded to the phase mask, and the fingerprint on the card is compared to a reference fingerprint of the card holder for added security.

Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.

Abstract: A method of and apparatus for efficiently correcting an aberration of an optical system used to record a hologram at the stage of reconstructing an image of the hologram. At the stage of reconstructing an image of a hologram (3), which contains the record of interference fringes formed by a reference plane wave and an object wave modulated by a sample, by applying a plane wave for reconstruction to the hologram (3) from a laser (1), an aberration of an optical system used to record the hologram (3) is canceled by the phase distribution on a liquid crystal panel (6) having a spatial phase modulation function, which is disposed on the Fourier transform plane, thereby correcting the aberration. The phase distribution on the liquid crystal panel (6) can be changed flexibly by a computer (9) in accordance with the aberration coefficients or degree of defocusing of the recording optical system.

Abstract: A Fourier transform hologram image is created on a sheet on the seal. The image is made, by making a die from the Fourier transform hologram image master plate and by molding resin on the die. The image formed on the sheet is reconstructed by an identification apparatus. The identification apparatus contains the laser emitting device and the screen for receiving the reflecting laser beam. The laser beam is illuminated vertically against the sheet from the laser emitting device. The laser beam reflected from the sheet surface is received by the screen, and the image of the sheet is reconstructed on the screen. At this time, it is possible to check whether the laser beam is reaching the sheet from an opening in the casing.

Abstract: An associative memory apparatus having a 2f Fourier transform optical correlation configuration wherein the correlation spots produced in the correlation plane are projected back by a mirror through the inverse Fourier transform lens and a phase correction reference image filter to produce the output image representing the best match between the input image and the associative memory reference images. A 4f Fourier transform embodiment projects the correlation spots forward through a second filter and transform means and the output image can be fed back to the input image display SLM to enhance the output image.

Abstract: The correlation speed and storage capacity of an optical disk-based correlator is enhanced by employing a thick (several hundred micron) photo- polymeric film (or other thick holographic media) on the disk as the recording media to permit volume holography and angular multiplexing of holograms in each spot on the disk. For example, if 100 holograms are multiplexed at one spot, 100 1-dimensional correlation functions can be read in parallel off of the disk while illuminating it with a single input image. The diffraction of the image beam by the recorded holographic patterns occurs at the holograms in the disk.

Abstract: 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 the crystal and is phase conjugated by a self pumped barium titanate phase conjugator, and the resulting phase conjugate beam reads out the hologram and multiplicative noise is substantially reduced in the optical output signal.

Abstract: An apparatus and method for image analysis utilizing an optical-electronic hybrid device. A light source generates light through an alternating series of lenses and electronically addressable spatial light modulators to an optical correlation plane. A first modulator introduces an input image and a second modulator introduces a Fourier transformed reference image into the device. The device correlates the input image and the reference image in the optical correlation plane. The optical correlation plane feeds back information through a processor to the second modulator which varies a parameter of the reference image. The second modulator varies parameters to determine the greatest correlation between the input image and the reference image. The parameters at the point of greatest correlation are used together with the reference image to identify the input image.

Abstract: A signal processing device used for processing images including an optical correlator combined with a neuonal processor.

Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.

Abstract: A motionless parallel head reads an optical disk having an active surface encoded with an arrayed multiplicity of one-dimensional holograms. Each 1-D hologram is a computer-encoded representation of, typically, one 128 pixel slice of an image. A group, typically 128, 1-D holograms are positionally distributed, and positionally shifted or staggered one to the next, radially along the disk's active surface so as to fit a complete radius. Typically 14,000 groups are circumferentially-displaced around a 51/4" Compact Disk (CD), forming a herringbone pattern. During readout the encoded CD is simultaneously illuminated along the entirety of one of its radius lines within which a group of holographic data blocks are fitted.

Abstract: 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 specifically oriented with respect to the input beams. An extraordinarily polarized, spherically converging object image beam is formed by laser illumination of an input object image and applied through a photorefractive crystal, such as a barium titanite (BaTiO.sub.3) crystal. A volume or thin-film difORIGIN OF THE INVENTIONThe invention described herein was made in the performance of work under a NASA contract, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected to retain title.

Abstract: A holographic optical correlator includes a matched optical filter and control means therefor including a memory. In use searching for occurrences of an item to be found is carried out by the control means controlling the input and Fourier transform planes of the filter and a coherent light source for parallel optical processing of the memory content and the output plane of the filter provides information to the control means as to the location in the memory of occurrences of said item. The complexity of the detector means in the output plane can be reduced in comparison with previous proposals by moving the item to be sought step-wise across the input plane. The detector means then may comprise a single column of detectors which are required to detect a peak correlation signal within a predetermined range.

Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.

Abstract: Methods for generating holograms from a computer model of any object employ a combination of numerical and optical means. An illumination model and the light dispersion properties of the object are specified. The hologram is synthesized from a plurality of smaller hologram elements. Each individual element sustains a field of view of the object. The light rays from the object lying within the field of view and along the lines of sight are sampled by the computer. The sample density should not exceed the resolution limit set by the size of the hologram element. Each light ray is specified by a direction and an amplitude function. The hologram element is obtainable from a Fourier Transform fo the sampled rays. In one embodiment, optical means are employed to physically reproduce the sampled light rays using coherent radiation. The reproduced coherent light rays are then interfered with a coherent reference beam to form the hologram element.

Abstract: A pulse train in the presence of random noise and other pulse trains is identified by controlling pixels in a raster display in accordance with incoming signals; using the raster display to modulate a laser beam with the pulses; Fourier-transforming the modulated beam, then performing a Cartesian to polar coordinate transformation on the Fourier-transformed beam; inverse Fourier transforming the coordinate-transformed beam, and passing the result through a line spatial filter and focusing the filtered beam on a one-dimensional detector array.

Abstract: A multiple target correlation system for unambiguously detecting, locating and determining the orientation of an array of multiple targets or objects. The multiple target correlator provides a means for fabricating a matched filter array or multiple matched filter with multiple targets stored on a single plate and a method for interrogating this multiple target matched filter with multiple scene images thereby providing for the identification of each object or target and determining its location and orientation in coordinates that are user selectable. The multiple target correlator utilizes a multiple matched filter having two matched filters for each particular object or target stored thereon, and each matched filter is positioned at a unique angle.

Abstract: An optical correlator console for mounting and assembling the components of an optical correlator system in a unique stable, compact and functional configuration in which all of the components are mounted in a compact configuration on upper and lower sides of a base support plate. The components which do not ordinarily require accessibility are mounted below the support plate and the components which ordinarily require accessibility during operation and use of the optical correlator are mounted above the support plate. The lower side of the support plate mounts a laser source and a collimator along with several other incidental optical components, with the laser source providing a laser beam as an input to the collimator which provides an expanded and collimated optical beam. The additional incidental optical elements can include a spatial filter and a shutter mounted interposed between the laser source and the collimator.

Abstract: The Fourier transform optical processing system of the present invention includes generating an electrical signal in response to a first image and modulating a beam of coherent light with means that is responsive to the electrical signal. A Fourier transform image of the modulated coherent light beam is formed, an then detected. The detector provides a second electrical signal representative of the Fourier transformed image. Other aspects of the invention include comparing the second electrical signal to a reference electrical signal for producing an output signal representing any differences; optically preprocessing the image; detecting the Fourier transform image and generating signals representative of its Fourier transform characteristics; and modulating a coherent light beam using a liquid crystal or other spatial light modulating device.

Abstract: Glints (e.g., images of point sources attributable to specular reflections) are suppressed in the focal plane of an optical imaging system by:a) Fourier-transforming an image of the imaging system's object field (including glints), and dividing the resulting energy distribution into a first channel and a second channel;b) focussing the energy in the first channel onto a first diffraction grating so as to impose a periodic carrier on the image, thereby producing a first image signal;c) directing the energy in the second channel so as to illuminate a Fourier-transform hologram of the complex point response of the imaging system to which additional aberrations (preferably toroidal aberrations) have been added;d) focussing the energy distribution from the hologram onto a second diffraction grating that is 180.degree. out-of-phase with the first diffraction grating, and blocking higher diffracted orders, thereby producing a second image signal;e) superimposing the first and second image signals (which are 180.

Abstract: An optical correlator according to the present invention generates a cross-correlation peak of two patterns of pictorial information to be compared. It generates pictorial patterns of a sum of the two patterns of pictorial information and of a difference between the two patterns of pictorial information by a phase conjugate waveform, transforms the pictorial patterns into first Fourier transform images, generates a pictorial pattern of a difference between an intensity distribution of the first Fourier transform images by the phase conjugate waveform, and transforms the pictorial pattern of a difference between an intensity distribution of the first Fourier transform images into second Fourier transform images. The optical correlator detects a cross-correlation peak of the two patterns of pictorial information for comparison at a high S/N ratio.

Abstract: Method of producing an averaged amplitude mask, for use in conjunction with a phase only filter (pOF) to provide an averaged amplitude matched filter (AAMF) in a Fourier transform optical correlator, involves intensity normalizing a plurality of reference images within a given class of objects, averaging the intensities of the reference images, Fourier transforming the resulting data, and utilizing the resultant amplitude function, exclusive of phase, of the Fourier transform to produce the averaged amplitude filter. A number of such masks are sequentially positioned adjacent the POF to very rapidly determine whether an input image falls within a particular class of objects, or whether the input image is of a particular object within the class.

Abstract: A discoid optical correlator system having a plurality of reflective optical components, a source of electromagnetic radiation, such as visible light, and an output detector which are positioned around the rim region of a solid disk body to develop a symmetrically folded optical axis traversed by a beam of electromagnetic radiation so that an unknown object is optically detected and identified.

Abstract: A method and apparatus for registering an image using coherent radiation. Spatial homodyne means are employed to generate component signals which comprise a homodyne equivalent of the image, and the component signals of the homodyne equivalent are registered at a registering medium. Using a new principle of construction, the invention achieves on standard registering media a substantial improvement in conrast resolution. Indeed, the number of contrast levels that can be registerd by the invention is the square of the number that can be registered by the prior art. The application of temporal submodulation in a device embodying the invention additionally provides tensor parasitic phase-shift invariance.

Abstract: An incoherent holographic correlator comprising a two-dimensional array of surface-emitting lasers which are selectable in an arbitrary pattern so as to emit a beam containing the pattern. The pattern is spatially incoherent because the lasers are not phase-locked but it is temporally coherent. The beams are collimated onto a recorded hologram, and each of the beams produces a diffracted beam from the recording. All the diffracted beams are focused onto an imaging plane. A high-intensity spot represents a strong correlation between the selected pattern on the laser array and the image previously recorded in the hologram.

Abstract: A keyless holographic locking device that uses a matched optical filter to store in form of a hologram a unique identificaton such as a fingerprint of an authorized user, a source of coherent light that provides the illumination, and an input element for providing angle-invariance possessing the form of a transparent window against which the user places and rotates the same fingerprint, and a registering device for registering the correlation optical signal between the stored fingerprint and the presented fingerprint to generate a signal to unlock the device when, and only if, a positive correlation exists between the presented and the stored fingerprints.

Abstract: Optical correlator technology is applied to optical computing in the form of an optical interconnect utilizing multiple Fourier transforms in a hologram-based design.

Abstract: An optical system for reading a plurality of radially contiguous individual holograms previously recorded on a rotatable disk along at least one of the disk tracks, each hologram being representative of a predetermined data pattern, and each being recorded as a Fourier transform hologram with respect tot the direction (y direction) tangential to the tracks and as a Fresnel hologram with respect to the radial direction (x direction), and wherein the optical system illuminates the disk with a read-out beam which is at least partially reflected by the disk to an array of photosensitive detectors which generates electrical data signals. A latch circuit is included for recovering the value of each data signal when the read-out beam completely illuminates one of the holograms.

Abstract: An image enhanced optical correlator system providing for optical preprocessing of an input image prior to processing thereof in an optical correlator. The optical preprocessing is provided to enhance the image and/or image related characteristics such that the probability of detection of prescribed targets therein in the optical correlator is increased. In the system, an input image beam is split into orthogonally polarized image inputs, processed to enhance targets therein, and then the algebraic result (addition and/or subtraction) thereof is processed through an optical correlator. Techniques are used in the feedback systems to enhance the output plane correlation signal detection by an adjustment in phase, spatial frequency filtering and/or threshold setting optimization.

Abstract: A method for generating holographic optical elements such as power spectrum filters is carried out using a printer and a computer. A signal function is input into the computer and traced by the printer to produce a power spectrum envelope of the signal function. The power spectrum is then filled in with a grating pattern whose line spacing is determined by the desired diffraction of coherent radiation beams used to interrogate the optical element.

Abstract: A mask repair method in which a transparent defect of in a phase shifter pattern is repaired by ion beam etching instead of a shifter pattern film deposition. A portion of the mask substrate below the transparent defect region is etched with an ion beam to a depth such that the phase of light passing through the adjacent transparent pattern regions and the phase of light passing through the etched region are opposite to each other. This mask repairing method enables high-contrast exposure and ensures high working accuracy since the repairing process is based on etching alone.

Abstract: An inexpensive wallpaper, which may be plastic and self adhesive. Using the positive features and advantages of thin-layer holograms and other existing technology, the claimed invention produces a changing, moving or stable 3-D effect in the presence of a low-powered laser illuminating system. In usual (incoherent) light, the claimed wallpaper reflects light as does a standard wallpaper. On the claimed wallpaper, images of any kind can be additionally printed without damaging the coherent 3-D reconstruction. The claimed wallpaper produces 3-D images, whose qualities are not affected by mechanical damage of any kind, including scratching or scraping, and it can also be produced in a washable embodiment. The suggested object incorporates recognized computer techniques, by which an image of any level of complexity can be included. The wallpaper can be printed on plastic or other media by sequentially applying a pre-prepared small-area matrix.