Abstract: The invention combines several techniques applying high-resolution photosensitive emulsions for the long-term, archival storage of data, images and text. Data is stored as vertical interference patterns of multiple frequencies in a photographic emulsion. Read-out of the stored data uses a precision mechanism to locate and decode stored data.

Abstract: A waveguide includes a cladding region that has a refractive index that is substantially uniform and surrounds a wave-guiding region that has an average index that is close to the index of the cladding. The wave-guiding region also contains a thin ring or series of rings that have an index or indices that differ significantly from the index of the cladding. The ring or rings enable the structure to guide light.

Abstract: In a system for authenticating information, a holographic element, including a first layer of optical information in a first coded pattern and a second layer of optical information in a second coded pattern is inserted into a reader. The reader includes an opening into which the holographic element may be positioned, a light source, a first detector positioned at a first predetermined distance from the location of the holographic element when the holographic element is positioned in the opening, and a second detector positioned at a second predetermined distance from the location of the holographic element when the holographic element is positioned in the opening.

Abstract: A reference beam telescope, which is also referred to as a relay imaging system for a reference beam, using reflection optics is disclosed. The relay imaging system according to the present invention comprises at least one concave mirror and one convex mirror. A reference beam is reflected at least twice by the concave mirror and once by the convex mirror. The output reference beam is collimated if the input reference beam is collimated. This relay imaging system is used in a holographic storage system to deliver the reference beam to the holographic storage medium. In particular, this system can be used for angular multiplexing in a holographic storage system.

Abstract: This invention relates to marking the genuine CD in an easily detectable way while difficult to counterfeit. The improved CD has within its layers a second structured surface parallel to the flat surfaces of the CD. The second structured surface acts as a diffractive security device, that is to be read out from the same side of the CD, the verso side, as the data structure. In one example, the second structured surface is defined by a step of the refractive index or by a transparent reflective layer. Despite the diffractive rainbow colors observed on the verso side of the CD, the structure of the security device can be read out visually and/or with a CD-reader, even by a simple hand-held reader, and verified without the need of a bulky apparatus. A CD-reader prevents the playing of embodiments of the improved CDs.

Abstract: Holographic memory including a beam source for emitting a beam, a beam splitter for splitting the beam into a reference beam and an object beam, a hologram memory unit for recording information designated to a cell when the reference beam and the object beam are incident thereto at a time, and reproducing the information recorded before when only the reference beam is incident thereto, a first optical path changing unit for directing the reference beam to be incident to the hologram memory unit at an arbitrary angle for recording and reproduction of the information, including a first deflector for deflecting the reference beam to an arbitrary angle, a second deflector for re-deflecting the reference beam deflected at the first deflector in a vertical direction, and a telescope having at least one composite HOE(Holographic Optical Element) for directing the reference beam re-deflected at the second deflector to be incident to the hologram memory unit, and a second optical path changing unit for adjusting an op

Abstract: A compact optical memory is disclosed in which data are stored in an optical data layer capable of selectively altering light such as by changeable transmissivity, reflectivity, polarization, and/or phase. The data are illuminated by controllable light sources and an array of multi-surface diffractive imaging lenslets cause a data image to be projected onto an array of light sensors by multiple reflections of, hence folding the image rays, by surfaces that both reflect and optically modify the light rays to redirect them onto the sensor array. Data are organized into an annular array of patches (called pages). By selective illumination of each data page, one of the lenslets images the selected data page onto a central image plane where the sensor array is located. Light in the data image pattern strikes different ones of the arrayed light sensors, thereby outputting information in the form of electrical data signals.

Abstract: The holographic storage and retrieval system according to the present invention comprises one convex reflector and one concave reflector having the same optical axis. The reflective surfaces of the two reflectors are opposite each other. The concave reflector is normally larger than the convex reflector. The holographic storage medium is positioned at the focal surface of the concave reflector. The spherical reflector system according to the present invention has nearly ideal performance off-axis: high bandwidth, low aberration imaging is permitted at a number of radial and axial locations. Thus, multiple SLM/CCD pairs can be placed off-axis to access the same storage medium and implement multiple interconnects.

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: In a system (apparatus and method) which employs a light absorbent material surrounded by an optically transparent matrix as a recording medium and in which the presence or absence of emission light of a specific wavelength from unity of the light absorbent material is used for optical writing and reading, the light emitted in response to reading light is condensed and spectrally diffracted and the light intensity is detected for each specific wavelength and related to recorded information.

Abstract: A recording element which comprises a recording layer containing, a first charge-generating material adapted to generate a first electric charge by a supply of external energy, a first charge-transporting material for transporting the first electric charge, a charge-capturing material for capturing the first electric charge, and a material having an electro-optical effect, wherein a change in optical properties of the recording layer is caused only through an inner electric field to be generated by a delivery of electric charge between the first charge-generating material generating electric charge and the charge-capturing material capturing the electric charge.

Abstract: 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 object beams directed thereto via cooperating reference beam and object beam scanners, respectively. The simultaneously angular and spatially multiplexed holograms are subsequently read-out by directing a reference beam through a desired location within the storage medium using the reference beam scanner. The reference beam is directed from the storage medium to a phase conjugator which conjugates the phase of the reference beam and directs the phase conjugated reference beam back to the same desired location within the storage medium so as to excite a corresponding conjugate object beam which is then directed onto a detector array.

Abstract: The invention is embodied in an optical memory having a holographic recording medium capable of storing respective holograms in respective storage spots, the memory including a coherent collimated reference beam and an information-bearing object beam illuminating the recording medium, a segmented optical array including a stack of plural segmented optical sub-arrays, each of the segmented optical sub-arrays including an array of generally parallel optical strips, each optical strip having a strip length extending parallel to the optical strips, respective optical strips of all of the sub-arrays providing an optical path for the reference beam to respective recording spots in the holographic recording medium whenever the reference beam is incident within the strip length, two optical strips in different sub-arrays with optical paths to the same recording spot being separated by at least an out-of-plane multiplexing difference angle subtended by paths of the reference beam to the two optical strips, a reference

Abstract: An optical memory stores data in an optical data layer capable of selecting altering light such as by changeable transmissivity. Data is organized into a plurality of regions or patches (called pages) in which each page contains a field of data spots storing binary data as the presence or absence of a hole. The data is illuminated by controllable light sources and an array of single element diffractive imaging lenslets, one for each data page, projects the image onto a common array of light sensors. By selective illumination of each data page, one of the single element lenslets images the selected data page of holes onto the light sensors. By selecting a hole size and using a certain range of restricted acceptance angle grooves on the diffractive elements, the data image is optimized for a single diffractive element lens.

Abstract: An optical memory is disclosed in which data is stored in an optical data layer capable of selectively altering light such as by changeable transmissivity or polarization. The data is illuminated by controllable light sources and an array of multi-surface imaging lenslets project the image onto a common array of light sensors. Data is organized into a plurality of regions or patches (called pages) in which each page contains a field of data spots that encode multiple states or levels of data by the amount of transmissivity or polarization of that spot. By selective illumination of each data page, one of the lenslets images the selected data page onto the light sensors. Light in the data image pattern strikes different ones of the arrayed light sensors, thereby outputting the multiple levels per spot in the form of electrical data signals that are A/D converted to digital.

Abstract: The present invention relates to polymeric materials that exhibit an erasable photorefractive effect which can be fabricated into optical devices such as optical wave guides.

Abstract: Disclosed is a spatial multiplexer for use with a holographic storage medium, and an information storage system employing the spatial multiplexer. The spatial multiplexer directs a reference beam of optical radiation onto the storage medium, the storage medium having (n) rows and (m) columns of storage locations. The spatial multiplexer includes an array of (n times m) discrete reflector elements each having a linear shape. The discrete reflector elements are disposed in a parallel arrangement with one another upon a substrate, and each has a different angular orientation with respect to the storage medium. A deflection of the reference beam by an angle multiplexer changes the angle of incidence of the reference beam on the storage medium, which provides multiple angles required for angle multiplexing a plurality of superimposed holograms within a single storage location.

Abstract: An improved Surface-Enhanced Raman Optical Data Storage System (SERODS) is disclosed. In the improved system, entities capable of existing in multiple reversible states are present on the storage device. Such entities result in changed Surface-Enhanced Raman Scattering (SERS) when localized state changes are effected in less than all of the entities. Therefore, by changing the state of entities in localized regions of a storage device, the SERS emissions in such regions will be changed. When a write-on device is controlled by a data signal, such a localized regions of changed SERS emissions will correspond to the data written on the device. The data may be read by illuminating the surface of the storage device with electromagnetic radiation of an appropriate frequency and detecting the corresponding SERS emissions. Data may be deleted by reversing the state changes of entities in regions where the data was initially written.

Abstract: This application concerns an optical storage with an optical storage medium having a plurality of storage fields arranged in matrix fashion, wherein each storage field of this storage field matrix comprises a storage position matrix consisting of a number of storage positions arranged in matrix fashion, and an X/Y deflection system for random-addressing a storage position of a storage field of the storage field matrix responsive to an X- and a Y-control signal generated by a control unit, so that a light beam impinging on the X/Y deflection system is directed to a storage position of a storage field of the optical storage medium corresponding to the position of the X/Y deflection system.

Abstract: In processes of holography using bacteriorhodopsin-based recording media, it is essential to design the signal-to-noise ratio to be as favorable as possible. This is achieved by recording the hologram using circularly polarized light and reconstructing the hologram by using linearly polarized light, specific beam components being selected as a function of polarization in the beam path of the reconstructed hologram. The process is suitable both for purely holographic applications and also for other processes which include one or more intermediate or partial steps involving holography.

Abstract: A photorefractive device is disclosed capable of optically coupling intersecting beams of electromagnetic radiation comprised of first and second electrodes for establishing a potential gradient between first and second spaced locations and, interposed between the electrodes, a photorefractive medium comprised of a homogeneous charge neutral organic photoconductor containing organic noncentrosymmetric molecular dipoles capable of imparting to the photorefractive medium a second order polarization susceptibility of greater than 10.sup.-9 esu, the molecular dipoles each containing an electron donor moiety linked through a conjugated .pi. bonding system to an electron acceptor moiety.

Abstract: An optical storage device having a mass storage medium which remains stationary as data is transferred by a laser. The stationary mass storage medium permits rapid data transfer since delay due to rotation of the medium, as in a compact disk, is eliminated.

Abstract: Recordable/erasable optical storage media are disclosed. The medium of the present invention generally comprises a rigid substrate, an expansion layer, a retention layer, and a dual-metal reflective layer. A single, active layer may be substituted for the expansion and retention layers. A protective layer may or may not be present. The dual-metal reflective layer comprises a first metal sublayer and a second metal sublayer with a graded first metal/second metal alloy at the interface of the first metal sublayer and the second metal sublayer. Methods for applying the dual-metal reflective layer to a polymer-coated substrate and substrates produced by such methods are also provided.

Abstract: An optical location system having a beam projection device (11, 51, 12, 13) to illuminate the field of view, and a detector array (29) to detect reflected light (21) from the field of view. The projected beam (13) is incrementably progressed across the field of view and for each increment the reflected points of light (61) detected by the detector (29) are recorded to build a map of the field of view, which is stored as a sparse array having as its first coordinate the angle of projection (A) of the illuminating beam (13) and as its second coordinate the azimuth angle (B) of the reflected ray detected by the detector. The value stored in each element of the array is the angle of the incidence (C) of the horizontal component of the detected ray with the detector.

Abstract: A finely detailed defraction grating is applied to an object as an identifier or tag which is unambiguous, difficult to duplicate, or remove and transfer to another item, and can be read and compared with prior readings with relative ease. The exact pattern of the defraction grating is mapped by diffraction moire techniques and recorded for comparison with future readings of the same grating.

Abstract: A method and apparatus for a Surface-Enhanced Raman Optical Data Storage (SERODS) System is disclosed. A medium which exhibits the Surface Enhanced Raman Scattering (SERS) phenomenon has data written onto its surface of microenvironment by means of a write-on procedure which disturbs the surface or microenvironment of the medium and results in the medium having a changed SERS emission when excited. The write-on procedure is controlled by a signal that corresponds to the data to be stored so that the disturbed regions on the storage device (e.g., disk) represent the data. After the data is written onto the storage device it is read by exciting the surface of the storage device with an appropriate radiation source and detecting changes in the SERS emission to produce a detection signal. The data is then reproduced from the detection signal.

Abstract: A photorefractive device is disclosed comprised of a first and second electrodes for establishing a potential gradient between first and second spaced locations and, interposed between the first and second electrodes, intermediate means capable of producing in a readout beam of electromagnetic radiation an image pattern corresponding to that present in a spatially intersecting writing beam of electromagnetic radiation when a potential gradient is applied to the intermediate means by said first and second electrodes. The intermediate means consists of a photorefractive layer capable of internally storing the image pattern of the writing beam created by its interference with an intersecting reference beam of electromagnetic radiation, the photorefractive layer being comprised of a homogeneous organic photoconductor containing organic noncentrosymmetric molecular dipoles capable of imparting to the photorefractive layer a second order polarization susceptibility of greater than 10.sup.-9 esu.

Abstract: An opto-magnetic signal reproducing apparatus includes a light source unit for applying a linearly polarized light beam to a recording medium having magnetically recorded information, a splitter for splitting the light beam modulated, responding to the recorded information by a magneto-optic effect, into two light beams having different polarization directions from each other, and a reproducing device for differentially detecting the split light beams to reproduce the recorded information. The splitter imparts a phase different equal to an integer multiple of .pi. to each of the split light beams.

Abstract: The head comprises a light source (S), a polarizer (P), a parabolic mirror (MP1), a second parabolic mirror (MP2), a polarization converter grating (RCP), a reflector (M), a separating plate (LS) and a detector (D). The beam diffracted by (RCP) constitutes a reference beam and the beam which has passed through (RCP) an analysis beam. The interference state of these two beams is dependent upon the orientation of the magnetization of the support to be read.

Abstract: Optical data storage members in which the guard bands present between data-carrying tracks of conventional data storage members are used to carry information recorded in a manner which avoids the danger of cross-talk between adjacent tracks. One preferred arrangement consists of an optical data storage member comprising an optically recordable surface having a plurality of tracks in which information may be recorded in analogue or digital form, the tracks being of a first type in which the material constituting the track is sensitive to radiation of a first predetermined characteristic and a second type in which the material thereof is sensitive to radiation of a second predetermined characteristic, wherein tracks of the first type alternate across the surface of the second type. The tracks may be constituted by a surface region (1,2,3,4,5) carrying a plurality of closely spaced grooves (11,12,13,14,15), the grooves of one track being orthogonally directed with respect to those of its adjacent tracks.

Abstract: An erasable, reusable recording element comprising a support having thereon a heat-deformable optical recording layer having a transparent overcoat is disclosed.

Abstract: Articles having on one surface thereof a linear prism array and a diffraction grating on the opposite surface are provided which are suitable for the preparation of projection transparencies.

Abstract: An optical memory with a storage plate and an optical write/read unit, with which during a relative movement the storage plate is illuminated pointwise for writing and reading of information, the storage plate and the optical write/read unit each being positioned in a coordinate with the aid of electromagnetic mechanical positioning means for addressing storage elements.

Abstract: The apparatus includes a frequency selective memory having a storage material for storing frequency holes in at least two spatial dimensions and a frequency dimension. Interference patterns are stored in the memory such that each complete interference pattern is found in the spatial dimensions while the series of interference patterns is in the frequency dimension. A laser beam is directed onto the surface of the memory to read the memory. By changing the electric field across the storage material, subsequent interference patterns are shifted in the frequency dimension into resonance with the laser beam thereby changing the interference pattern detected. The interference patterns may be a series of holographic interference patterns which would provide as an output a series of three dimensional images, or they may be a series of gratings which would provide a laser beam which scans in a spatial dimension as an output.

Abstract: The invention relates to a reversible memory structure with thermo-optical inscription or writing and optical reading on a moving support.According to the invention, the memory structure deposited on a substrate (1) is constituted by a double layer (2 and 3). A second alloy layer (3) at ambient temperature in the martensitic phase is deposited on a first thermally deformable layer (2). A heat pulse creates a deformation in the first layer, which deforms the martensitic alloy layer. A more powerful heat pulse raises the alloy layer to a temperature above its transformation point from the martensitic phase to another crystallographic phase and erases the inscribed deformation.Particular application to optical disks.

Abstract: For playback of a disc record information track, in which regions of a light reflective surface overlaid with a layer of light absorptive material alternate with regions of said light reflective surface free of said overlying absorptive material, light of a constant intensity is focused on the information track as the disc is rotated. The focused light is of insufficient intensity to effect ablation of the remaining absorptive material, but is of a frequency at which the overlaid regions of the coated disc exhibit an anti-reflection condition. A photodetector, positioned to receive light reflected from the information track as the pits pass through the path of the focused light, develops a signal representative of the recorded information.

Abstract: A process for coding a set of access cards adapted to control an apparatus for opening, locking or releasing a processing device and for the ultimate determination of the validity of a card when it is presented in the apparatus, the coding being effected by the formation on the cards of at least one diffraction grating whose recognition is effected by projection of a luminous beam on the grating and analysis of the diffracted beams. The grating is formed by means of a machine having a kinematic drive which is intentionally irregularized to produce at least one deviation in the spacing of the lines of the grating which varies periodically with a determined period and maximum amplitude. The modified grating will produce a supplementary satellite diffraction beam when illuminated by the luminous beam and whose angular position and intensity is measured to establish the validity of the grating.

Abstract: A video recording disk that is optically readable has data represented in a form that permits data track revolutions to be spaced close together without an intervening guardband or with only a narrow guardband. The track revolutions are in two sets that form a parallel spiral or alternating concentric circles so that a track revolution of one set is separated from other track revolutions of the same set by intervening track revolutions of the other set. Binary data is represented on the tracks by deformations or the absence of deformations, and the record is read as destructive interference in a light beam produced at the location of a deformation. Deformations of the first set of tracks have a depth that is appropriate to be read with a wavelength designated lambda 1, and deformations of the second set have a depth to be read by light of a wavelength lambda 2.

Abstract: Apparatus for reading a record carrier provided with a spiral structure in which sound and/or image information is stored in the form of frequency modulated or phase modulated signals is disclosed. The carrier structure is composed of coplanar regions of variable length separated by coplanar areas of variable length. Where the regions and areas are all in the same plane the regions and areas have different coefficients of reflection or transmission. Where the regions and areas are not coplanar they are spaced by a distance sufficient to produce in response to impinging radiation a one-half wave length difference in the radiation exiting the regions and areas. The apparatus provides a light beam with a frequency that facilitates diffraction of the beam by the areas and regions, and also provides a radiation sensitive detection system for converting the light beam modulations caused by the record carrier into a corresponding electrical signal.

Abstract: An apparatus optically reproduces FM electric signals from the recording medium recorded with said electric signals in the form of a change in refraction index. The apparatus is so constructed that a pair of laser beams are incident on the recording medium at substantially the same point with an angle defined between the laser beams; a diffracted light obtained by causing each of said beams to be diffracted, upon being transmitted through the recording medium, in accordance with the phase change pattern thereof is overlapped on a non-diffracted light obtained by causing the each of said beams to be transmitted through the recording medium without being diffracted; and optically phase-modulated signals are detected as a beat output produced by optical mixing of the diffracted light with the non-diffracted light, thus to reproduce a recorded signal.

Abstract: A videodisc system utilizes a beam of light which tracks the center of an interrupted spiral information channel. The light beam is "dithered" from side to side of the channel in order to determine the relative "direction" of a beam deviating from the center of the channel. The beam oscillates by approximately one-third of the width of the channel. By multiplying the returned signal by the drive signal, a signal is derived whose mean value is positive on one side of the track, negative on the other side and zero when in the center of the track.

Abstract: A record carrier is described which is provided with an optically readable structure of trackwise arranged areas alternating with intermediate areas. Areas of at least two different types are provided. As a result, a high information density can be achieved. The different types of areas may also be used for centering a read beam relative to a track and for focussing the beam onto the track.