Holographic process and media therefor
AssigneeLucent Technologies Inc.
InventorsVicki L. Colvin, Kevin Richard Curtis, Alexander Lowe Harris, Howard Edan Katz, Marcia Lea Schilling, William Larry Wilson
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Abstract
High storage densities using a holographic system are achievable using a stratified medium while maintaining a relatively high selectivity upon reconstruction of the stored images. Such combination of high density and high selectivity is achievable by employing a stratified medium and a recording process where selectivity does not vary with recording thickness.
Claims16
A process for recording multiple holograms in a holographic recording medium in which an array of individual partially overlapping holograms is recorded in the recording medium, the process comprising recording each individual hologram at an individual location by interfering a reference beam and a signal beam, and by moving the medium and the beams relative to each other to locate each individual hologram, the reference beam as measured at the position of interference comprising a phase beam of unchanging content containing a multiplicity of rays of non-uniform angle of incidence and of non-uniform phase, the reference beam further having a position-to-position self-similarity such that its auto-correlation function has a value which is sufficiently small to enable selection of individual holograms of the array, the process characterized in that the recording medium comprises a multiplicity of layers at least two of said layers are active layers that comprise material sensitive to said interfering reference beam and signal beam, said active layers separated in the propagation direction of the reference beam by a region comprising a layer that is inactive such that the ratio of the average thickness of the active layer to the thickness of the inactive layer is smaller than 10:1.
A stratified medium having regions with a multiplicity of patterns of variation constituting a multiplicity of stored holograms, said patterns produced by a first interaction of signal light and reference light followed by subsequent interactions of a signal light and said reference light wherein said stratified medium comprises at least two layers each containing said patterns separated by a layer essentially without patterns wherein the ratio of the average thickness of said layer with said patterns to the thickness of said layer without patterns is smaller than 10:1 and wherein said multiplicity of patterns are reconstructable individually by the process comprising illumination with a readout beam which is successively positioned by movement of the beam and the stratified medium relative to each other in order to locate each hologram, the readout beam, as measured at the medium, being a phase beam of unchanging content containing a multiplicity of rays of non-uniform angle of incidence and of non-uniform phase, the readout beam further having a position-to position self-similarity such that its auto correlation function has a value which is sufficiently small to enable selection of individual holograms.
Dependencies are inferred from the claim text.