Method of recording and reading angle-multiplexed holograms that compensates for media shrinkage
A method of recording a plurality of holographic images in a holographic media, comprising recording a sequence of multiplexed holograms in a selected storage location in the holographic recording media, each hologram having a respective interbeam angle. The interbeam angle increases for each subsequently recorded hologram to compensate for a variable shrinkage of the holographic media during recording. The multiplexed holograms recorded at the selected storage location are partially or fully overlapped. During reading the recorded holograms, a reference beam is directed at a selected storage location in the holographic recording media at a sequence of incidence angles, each incidence angle being adjusted by a respective adjustment angle. The adjustment angles can be substantially equal.
1 . A method of recording a plurality of holographic images in a holographic media, comprising:
recording a first hologram of a plurality of multiplexed holograms in a selected storage location in the holographic recording media with a first interbeam angle; and
recording a second hologram of a plurality of multiplexed holograms in the selected storage location in the holographic recording media with a second interbeam angle,
wherein the second interbeam angle is larger than the first interbeam angle, and wherein the multiplexed holograms at the selected storage location are partially or fully overlapped.
2 . A method of reading a plurality of holographic images recorded in a holographic media, comprising:
directing a reference beam at a selected storage location in a holographic recording media at a first incidence angle adjusted by a first adjustment angle;
detecting and thereby reading a first hologram of a plurality of multiplexed holograms recorded in the selected storage location;
directing a reference beam at the selected storage location at a second incidence angle adjusted by a second adjustment angle; and
detecting and thereby reading a second hologram of the plurality of multiplexed holograms recorded in the storage location,
wherein the first and the second adjustment angles are substantially equal.
3 . A method of recording a plurality of holographic images in a holographic media, comprising:
recording a sequence of multiplexed holograms in a selected storage location in the holographic recording media, each hologram recorded with a reference beam and a signal beam having a respective interbeam angle therebetween,
wherein the interbeam angle is increased for each subsequently recorded hologram to compensate for a variable shrinkage of the holographic media during recording at the selected storage location, and
wherein the multiplexed holograms recorded at the selected storage location are partially or fully overlapped.
4 . A method of reading a plurality of holographic images recorded in a holographic media, comprising:
directing a reference beam at a selected storage location in the holographic recording media at a sequence of incidence angles, each incidence angle being adjusted by a respective adjustment angle with respect to a recording angle of a reference beam used for recording the holographic image at a selected storage location; and
detecting a plurality of multiplexed overlapping or partially overlapping holograms recorded at the selected storage location,
wherein the adjustment angles differ by less than about 0.2°.
5 . The method of claim 4 , wherein the adjustment angles differ by less than about 0.1°.
6 . The method of claim 4 , wherein the adjustment angles differ by less than about 0.05°.
7 . The method of claim 4 , wherein the adjustment angles are substantially equal.
8 . The method of claim 4 , wherein each hologram in the plurality of multiplexed overlapping or partially overlapping holograms is recorded with a reference beam and signal beam having a respective interbeam angle therebetween, wherein each said interbeam angles is increased for subsequently recorded hologram to compensate for a variable shrinkage of the holographic media during recording at the selected storage location.
9 . A method of reading a plurality of holographic images recorded in a holographic media, comprising:
directing a reference beam at a selected storage location in the holographic recording media at one or more incidence angles, each incidence angle being adjusted by a respective adjustment angle with respect to a recording angle of a reference beam used for recording the holographic image at a selected storage location; and
detecting a plurality of multiplexed overlapping or partially overlapping holograms recorded at the selected storage location,
wherein each adjustment angle is less than about 0.2°.
10 . The method of claim 9 wherein each adjustment angle is less than about 0.1°.