Patent ID: 6293898
Filing Date: 2001-09-25
Classification: G02B,G11B,G11C

Abstract:
A holographic memory, comprising:a light source for emitting a beam;a beam splitter for splitting the beam into a reference beam and an object beam;a hologram memory unit for recording information on a cell to which the reference beam and the object beam are incident together, and reproducing information recorded previously when only the reference beam is incident thereto;a first beam path changing unit for directing the reference beam to an arbitrary direction for recording and reproducing the information;a composite HOE having a plurality of HOEs (Holographic Optical Element) stacked in a vertical direction each for diffracting the reference beam from the first beam path changing unit toward an arbitrary cell of the hologram memory unit; and,a second beam path changing unit for adjusting a beam path of the object beam such that the object beam is incident to the hologram memory unit for recording the information;wherein the second beam path changing unit includes:a first beam blocking unit for passing the object beam incident thereto in recording and blocking the object beam incident thereto in reproduction;a beam deflector for deflecting the object beam passed through the beam blocking unit toward an arbitrary direction:a beam expander for expanding a diameter of the object beam deflected at the third beam deflector;a reflector for changing a direction of advance of the object beam expanded by the beam expander;a light modulator for displaying the object beam incident to the reflector;a lens for subjecting the object beam displayed on the light modulator to Fourier transformation, to provide to the hologram memory unit; andan optical detector for converting optical information reproduced from the hologram memory unit into an electrical signal in reproduction.