Holographic memory with angle, spatial and out-of-plane multiplexing

Abstract

The invention is embodied in an optical memory having a holographic recording medium capable of storing respective holograms in respective storage spots, the memory including a coherent collimated reference beam and an information-bearing object beam illuminating the recording medium, a segmented optical array including a stack of plural segmented optical sub-arrays, each of the segmented optical sub-arrays including an array of generally parallel optical strips, each optical strip having a strip length extending parallel to the optical strips, respective optical strips of all of the sub-arrays providing an optical path for the reference beam to respective recording spots in the holographic recording medium whenever the reference beam is incident within the strip length, two optical strips in different sub-arrays with optical paths to the same recording spot being separated by at least an out-of-plane multiplexing difference angle subtended by paths of the reference beam to the two optical strips, a reference beam steering apparatus for scanning the reference beam to different locations on the segmented optical array, and a modulator apparatus for modulating the object beam with a succession of input patterns simultaneously with the scanning of the reference beam by the reference beam steering apparatus so as to record a plurality of angle multiplexed and out-of-plane multiplexed holograms in at least one of the recording spots. Each of the sub-arrays corresponds to a different out-of-plane multiplexing angle of the reference beam.