Three Dimensional Optical Information Storage System.
DEPARTMENT OF THE NAVY WASHINGTON D C
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A system for storing information in or retrieving information from a three dimensional memory element is described in the patent. The storage principle is based upon aligning anisotropic color centers in alkali halide crystals and thereby producing dichroic absorptions which are equated to the stored information. The ability to write in the interior of the crystal is based on the fact that one can suppress the reorientation of these color centers with infrared excitation. Information states are thus established at interior regions by simply shielding those portions from the infrared excitation. Information is retrieved from the interior of the memory element by exposing it to excitation principally for the purpose of producing a transient color center absorption lying in an otherwise transparent region of the spectrum. The interrogation excitation would lie in this same spectral region.