Patent ID: 6909529

Claim:
A holographic storage apparatus for recording data in a holographic medium including: at least one light source for generating a reference beam and a signal beam, the reference beam being a phase correlation beam of unchanging phase content; a holographic medium having at least a first face and placed in a path of the reference beam and a path of the signal beam such that both the reference beam and the signal beam enter the holographic medium through the first face to interfere in the holographic medium to create a hologram; the holographic medium further including a data reflective surface such that in reading information stored in the holographic medium both the reference beam and an output beam pass through the first face of the holographic medium; a chase mask positioned in a path of the reference beam between the at least one light source and the holographic medium, the chase mask to phase modulate the reference beam prior to reaching the holographic recording medium; a Fourier transform lens positioned in a path of the reference beam after the phase mask and to generate a Fourier transform of the reference beam; a filter block having an absorptive face and a reflective face and positioned such that the absorptive face includes an opaque filter positioned relative to the path of the reference beam such that in recording data in the holographic medium, the opaque filter blocks a center region of the Fourier transform of the reference beam from reaching the holographic medium, the blocked center region including zeroth order Fourier components of the Fourier transform of the reference beam and the reflective face includes a signal beam reflective surface positioned in the path of the signal beam before the holographic media for turning the signal beam along a oath that is substantially parallel to an optical axis of the reference beam, to cause the signal beam to enter the holographic medium through the first face thereof; and wherein in reading information stored in the holographic medium the reference beam is spatially separated from the output beam irrelevant of polarization.