# US 5,703,705 A · Tilt multiplex holography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,705 A - Document ID: US5703705A - Status: Granted - Kind: A - Application number: 08/435,706 - Filed: 1995-05-05 - Granted: 1997-12-30 - Earliest claimed: 1995-05-05 - Assignees: Lucent Technologies Inc. - Inventors: Kevin Curtis; William Larry Wilson - Web page: https://patentgrep.com/patent/US5703705A ## CPC - G11B 7/0065: Recording, reproducing or erasing by using optical interference patterns, e.g. holograms - G03H 1/2645: {Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing} - G03H 1/265: {Angle multiplexing; Multichannel holograms (G03H1/268 takes precedence)} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00}) ## Abstract A system for high density holographic storage announced by Cal Tech is improved. The basic Cal Tech system records successive holograms by physically shifting the recording medium relative to the paired reference and signal beams. By depending on Bragg selectivity, successive holograms may be overlapped and still differentiated in the direction of overlap--in the "x-direction". The claimed system improves storage density by tilting the holographic plane to introduce a Bragg component in the y-direction, thereby enabling differentiation of overlapping holograms in that direction as well. ## Claims ### Claim 1 Process for shift holography in which an array of holograms is recorded in a recording medium defining the x-y plane, the array consisting of holograms each produced by interference of a reference beam and a signal beam together defining a plane of incidence, and each consisting of a multiplicity of holographic grating vectors having a predominant grating vector direction in the x-y plane, the array consisting of successive rows of partially overlapping holograms produced by movement of the recording medium relative to the beams in the shift direction, thereby defining the x-direction, with successive rows produced by movement in the direction orthogonal to the shift direction, thereby defining the y-direction, whereby partially overlapping holograms may be individually read out using Bragg selection, CHARACTERIZED IN THAT the line of interception of the plane of incidence and the x-y plane is non-coincident with the shift direction, and diverges by a divergence angle as measured in the x-y plane, whereby a grating vector component is introduced into the y-direction, thereby permitting first-order Bragg selectivity in the y-direction and serving for selection of partially overlapping holograms in the y-direction. ### Claim 2 (depends on 1) Process of claim 1 in which the divergence angle is at least 5.degree.. ### Claim 3 (depends on 2) Process of claim 2 in which the angles made by a line between the z-direction and the x-z components of the signal beam and the reference beam are equal. ### Claim 4 (depends on 1) Process of claim 1 in which the plane of incidence is orthogonal to the x-y plane. ### Claim 5 (depends on 4) Process of claim 4 in which the divergence angle is approximately 45.degree.. ### Claim 6 (depends on 1) Process of claim 1 in which the reference beam is substantially cylindrical. ### Claim 7 (depends on 1) Process of claim 1 in which the reference beam is constituted of multiple plane waves. ### Claim 8 (depends on 1) Process of claim 1 in which the reference beam is substantially spherical. ### Claim 9 (depends on 1) Process of claim 1 in which the recording medium is substantially planar. ### Claim 10 (depends on 1) Process of claim 1 in the array comprises overlapping rows of overlapping holograms. ### Claim 11 (depends on 10) Process of claim 10 in which an individual row is recorded prior to a sequential row. ### Claim 12 (depends on 10) Process of claim 10 in which rows are substantially straight and parallel. ### Claim 13 (depends on 10) Process of claim 10 in which rows are substantially circular. ### Claim 14 (depends on 10) Process of claim 10 in which holograms in x- or y-direction are staggered. ### Claim 15 (depends on 1) Process of claim 1 in which relative motion between the medium and the beams is produced by moving the medium relative to stationary beams. ### Claim 16 (depends on 1) Process of claim 1 in which shifting is accomplished by moving the beams relative to the recording medium. ### Claim 17 (depends on 1) Process of claim 1 in which the process includes a reconstruction step in which holograms are reconstructed. ### Claim 18 Process for shift holography comprising reconstruction of holograms within an array of holograms in a medium, the array consisting of successive overlapping rows of overlapping holograms, the process comprising illuminating selected holograms by a readout beam and detecting a resultant reconstructed image produced by a reconstructed image beam, the two beams defining a readout plane, in which selection is by positioning of the readout beam relative to the medium, whereby partially overlapping holograms are individually reconstructed using Bragg selectivity, CHARACTERIZED IN THAT row direction differs by an angle of divergence from the line of intersection of the readout plane and the medium. ### Claim 19 (depends on 18) Process of claim 18 in which the divergence angle is at least 5.degree.. ### Claim 20 (depends on 19) Process of claim 19 in which the readout plane is orthogonal to the medium. ### Claim 21 (depends on 19) Process of claim 19 in which the divergence angle is approximately 45.degree.. ### Claim 22 (depends on 18) Process of claim 18 in which the reference beam is substantially cylindrical. ### Claim 23 (depends on 18) Process of claim 18 in which the reference beam is constituted of multiple plane waves. ### Claim 24 (depends on 18) Process of claim 18 in which the reference beam is substantially spherical. ### Claim 25 (depends on 18) Process of claim 18 in which the recording medium is substantially planar. ### Claim 26 (depends on 18) Process of claim 18 in which rows are substantially straight and parallel. ### Claim 27 (depends on 18) Process of claim 18 in which rows are substantially circular. ### Claim 28 (depends on 18) Process of claim 18 in which relative motion between the medium and the beams is produced by moving the medium relative to stationary beams. ### Claim 29 (depends on 18) Process of claim 18 in which shifting is accomplished by moving the beams relative to the recording medium. ### Claim 30 (depends on 18) Process of claim 18 including recording of at least one hologram. ### Claim 31 (depends on 18) Process of claim 18 in which the array comprises portions, each portion including multiple holograms, the process providing for access to selected portions of the array. ### Claim 32 (depends on 31) Process of claim 31 in which the medium is in the possession of a user and access information for accessing a portion is in the possession of a service provider. ### Claim 33 (depends on 18) Process of claim 18 in which information required for access is restricted to qualified users.