Application of self-developing dichromated gelatin for holographic data storage with speckle shift multiplexing

THe hologram multiplexing method for the 3D data storage with speckle reference wave is considered. It permits to multiplex holograms by shifting of the speckle wave on the value equal to the its correlation radius. The limit of the number of information units presented by this type of holographics storage exceeds the same value for the spectral or angular multiplexed holograms. However, the system noises reduce it to the regular value. Two different experimental set-ups were tested for the holograms recording: with incident beams and with included beams. It occurred that the number of information units that can be stored in unit volume is larger in the case when both beams possess speckle structures, however the signal-to-noise ratio is also larger in this case, so the spatial modulation of the object beam does not improve the information capacity. Holograms recording was carried out using volume photosensitive medium: newly developed self processing dichromated gelatin of 0.5 mm thickness, and it was compared with the recording in DuPont photopolymer of 100 micron thickness and Fe:LiNbO 3 crystal of 2 mm thickness. The method seems to be very suitable for the laser-disk-memory devices.