# US 11,308,988 B2 · Holographic multiplexed recording method for increasing storage capacity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,308,988 B2 - Document ID: US11308988B2 - Status: Granted - Kind: B2 - Application number: 17/135,287 - Filed: 2020-12-28 - Published: 2021-07-01 - Granted: 2022-04-19 - Earliest claimed: 2019-12-31 - Assignees: Amethystum Storage Technology Co., Ltd. - Applicants: Amethystum Storage Technology Co., Ltd. - Inventors: Mu Zheng; Tiewei Luo; Jun Tian; Dejiao Hu; Yicheng Liu - Web page: https://patentgrep.com/patent/US11308988B2 ## CPC - G11B 7/0065: Recording, reproducing or erasing by using optical interference patterns, e.g. holograms - G11B 7/083: {relative to record carriers storing information in the form of optical interference patterns, e.g. holograms} - 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 holographic multiplexed recording method for increasing storage capacity is disclosed. In a holographic recording and reproducing device, the moving direction of a storage medium is not coplanar with the plane where the optical axes of signal light and reference light are located, or the relative moving direction of the storage medium and the signal light or the reference light is not coplanar with the plane where the optical axes of the signal light and the reference light are located. Through the method, a certain angle exists between the grating vector direction and the moving direction or the relative moving direction, so that the phenomenon that the grating vector directions are the same does not occur when the medium is subjected to multiplexed recording after being rotated or flipped. Not only is multiplexing number increased, but also crosstalk caused by the same grating vector direction is prevented. ## Claims ### Claim 1 A holographic multiplexed recording method for increasing storage capacity, wherein in a holographic recording and reproducing device, a moving direction of a storage medium is not coplanar with a plane where an optical axis of signal light and reference light are located, or a relative moving direction of a storage medium and signal light or reference light is not coplanar with a plane where an optical axis of the signal light and the reference light are located, and wherein the storage medium rotates with its surface normal as an axis, so that the moving direction thereof forms an angle φ with the plane where the optical axes of the signal light and the reference light are located, and φ is from 5° to 45°. ### Claim 2 (depends on 1) The holographic multiplexed recording method according to claim 1, wherein the angle φ formed by the moving direction of the storage medium and the plane where the optical axes of the signal light and the reference light are located is 30°. ### Claim 3 (depends on 1) The holographic multiplexed recording method according to claim 1, wherein a two-dimensional hologram array can be obtained by arranging and recording multiple rows of holograms in parallel, then a new hologram array can be multiplexed and recorded after the storage medium is rotated at a fixed angle, and the fixed angle is called a cross angle α. ### Claim 4 (depends on 3) The holographic multiplexed recording method according to claim 3, wherein the recording process specifically comprises the following steps: S1. recording the two-dimensional hologram array by means of shift multiplexing; S2. rotating the storage medium at the cross angle α with its surface normal as the axis; and S3. repeating steps S1 and S2 n times, and ending when n=[360°/α]−1 is satisfied. ### Claim 5 (depends on 3) The holographic multiplexed recording method according to claim 3, wherein the cross angle α at which the storage medium rotates is equal to or greater than 40°. ### Claim 6 (depends on 5) The holographic multiplexed recording method according to claim 5, wherein the cross angle α=360°/m, and m is an integer from 1 to 9. ### Claim 7 (depends on 6) The holographic multiplexed recording method according to claim 6, wherein the cross angle α is 90°. ### Claim 8 (depends on 1) The holographic multiplexed recording method according to claim 1, wherein a new hologram is recorded and reproduced from the back after the storage medium is flipped. ### Claim 9 (depends on 8) The holographic multiplexed recording method according to claim 8, wherein the recording process specifically comprises the following steps: S1. recording the two-dimensional hologram array by means of shift multiplexing; S2. rotating the storage medium at the cross angle α with its surface normal as the axis; S3. repeating steps S1 and S2 n times, performing cross-shift multiplexing storage, and ending the recording on a first side of the storage medium when n=[360°/α]−1 is satisfied; S4. flipping the storage medium with an axis perpendicular or parallel to the moving direction; and S5. repeating steps S1 to S3 on a second side of the storage medium. ### Claim 10 (depends on 1) The holographic multiplexed recording method according to claim 1, wherein the new hologram is recorded and reproduced by tilting the medium or making the reference light and signal light incident asymmetrically with respect to the storage medium, and a holographic grating vector formed by the interference between the reference light and the signal light on the storage medium forms an angle with the surface of the storage medium. ### Claim 11 (depends on 10) The holographic multiplexed recording method according to claim 10, wherein the recording process specifically comprises the following steps: S1. recording the two-dimensional hologram array by means of shift multiplexing; S2. rotating the storage medium at the cross angle α with its surface normal as the axis; S3. repeating steps S1 and S2 n times, performing cross-shift multiplexing storage, and ending the recording on a first side of the storage medium when n=[360°/α]−1 is satisfied; S4. flipping the storage medium with an axis perpendicular or parallel to the moving direction; and S5. repeating steps S1 to S3 on a second side of the storage medium. ### Claim 12 A storage medium, comprising a multilayer-multiplexed two-dimensional hologram array, wherein the two-dimensional hologram array comprises an X-axis direction and a Y-axis direction, each layer comprises the recording of arranging multiple rows of holograms in parallel along the X-axis direction, the projection, on a storage medium plane, of a holographic grating vector formed by the interference between reference light and signal light on the storage medium forms an acute angle φ with the X-axis or Y-axis, and φ is from 5° to 45°. ### Claim 13 (depends on 12) The storage medium according to claim 12, wherein a fixed angle α exists between the projections of holographic grating vectors of each layer on the storage medium plane, and α is equal to or greater than 40°. ### Claim 14 A holographic recording and reproducing device for recording and reproducing a signal on a storage medium, comprising: a recording unit, configured to generate signal light and reference light; a storage medium moving unit, configured to drive the storage medium to move so that the moving direction of the storage medium is not coplanar with the plane where the optical axes of the signal light and the reference light are located; a storage medium rotating unit, configured to drive the storage medium to rotate with its plane normal as an axis; and a storage medium flipping unit, configured to drive the storage medium to flip with an axis perpendicular or parallel to the moving direction. ### Claim 15 (depends on 14) The holographic recording and reproducing device according to claim 14, further comprising a storage medium tilting unit, configured to drive the storage medium to tilt. ### Claim 16 (depends on 14) The holographic recording and reproducing device according to claim 14, wherein the recording unit comprises a reference light deflecting device or a signal light deflecting device that changes the incident angle of the reference light or the signal light to make it incident asymmetrically.