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US 4,063,226 AGranted
Optical information storage system
AssigneeHarris Corporation
InventorsAdam Kozma, Anthony Vander Lugt, Andrew M. Bardos
Life of this patent
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AssigneeHarris Corporation
InventorsAdam Kozma, Anthony Vander Lugt, Andrew M. Bardos
Estimating the term…
A wideband holographic information storage system records Fourier holograms on film in rapid succession, each hologram storing 128 bits of data. The hologram fringe pattern is held stationary by varying the reference beam frequency to track the variations of frequency of the signal beam that are caused by acoustic-optic modulation of the signal beam. Holograms are successively recorded in adjacent positions by scanning a light beam across a photosensitive film with a rotating polygonal mirror, the recording light beam being wide enough to cover two facets of the mirror so as to achieve nearly 100% scanning duty cycle. During readout, a readout light beam is steered to compensate for prismatic deflection effects caused by variations in thickness of the film. The direction of the output beam is maintained constant despite a scanning motion of the incident readout beam, by reflecting the output beam a second time from a different facet of the polygonal mirror to compensate the rotational component of beam motion. Clocking of output data is self-synchronized, based upon modulation signals. Acoustically caused defocusing of the light beam is optically corrected. Methods are employed to reduce crosstalk.
An information storage system comprising a member bearing a spatially distributed record of information stored in a form adapted for readout by a scanning light beam, light source means for producing a beam of light propagating in a first direction along a first longitudinal segment of said beam, first light deflection means at the end of said first beam segment for deflecting said beam to propagate in a second general direction along a second longitudinal beam segment to said information bearing member, said member disposed in the light path for modulating the light beams by said information, said modulated beam that follows said member propagating along a third longitudinal beam segment, second light deflection means at the end of said third beam segment for deflecting said beam to propagate in another direction as a fourth beam segment, and means for rotatably moving said first light deflection means about an axis substantially perpendicular to the plane defined by said first and second beam segments for scanning said second beam segment across said member, and for rotatably moving said second deflection means about said axis so as to substantially eliminate any rotational component of motion from said fourth beam segment.
A method for use in an information storage system having a member bearing spatially distributed record of information comprising the steps of establishing a light beam from a light source, said beam having a plurality of longitudinally spaced beam segments, deflecting a first segment of the beam by means of a first light deflector to propagate along a second segment of the beam to the information-bearing member, moving said first light deflector about an axis which is substantially perpendicular to the plane defined by said first and second segments to scan said second beam segment across said information-bearing member, producing a modulated third beam segment by modulating said second segment with said information record, deflecting the third beam segment by a second light deflector to propagate along a fourth beam segment, and moving said second light deflector about said axis in synchronism with said first light deflector in a motion adapted to substantially eliminate any rotational component of motion from said fourth beam segment.
An information storage system comprising a light source means for providing a light beam propagating along a first longitudinal beam segment;
A method for use in an information storage system having a light beam divided into beam segments following one another along the direction of propagation of said light beam and having a member for storage of a spatially distributed information record across which a segment of said beam is to be scanned comprising the steps of translating a first light-deflection means transversely into, across, and out of a first segment of said beam while simultaneously rotating said first deflection means to scan a deflected second segment of said beam across said first beam segment far enough to achieve full transverse illumination thereof by said first beam segment while said first deflection means is also still substantially fully transversely illuminated by said first beam segment to transfer illumination scanning services from said first to said second deflection means substantially without interruption;
A method for use in an information storage system as defined in claim 13 and wherein said step of translating a first light-deflection means into, across, and out of a first segment of said beam while simultaneously rotating said first deflection means to scan a deflected second segment of said beam across said storage member which comprises a step of revolving a first mirror about an axis spaced apart from the reflecting surface plane of said first mirror and wherein said step of translating and rotating said second deflection means comprises a step of revolving a second mirror about said axis, the reflecting surface of said second mirror being spaced apart from said axis.
Dependencies are inferred from the claim text.