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US 7,623,279 B1Granted
Method for holographic data retrieval by quadrature homodyne detection
AssigneeInPhase Technologies, Inc.
InventorMark R. Ayres
Life of this patent
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Abstract
Systems and methods for recovering data in a holographic memory system. The systems and methods use homodyne detection to introduce a local oscillator beam into a reconstructed data beam of the recovered hologram. An image of the combined beam comprising the reconstructed data beam and local oscillator beam may be processed to obtain contrast level information for the pixels of the detected image. This contrast level information may then be used to obtain an increased contrast image of the recovered hologram, which may increase the SNR of the recovered data.
Claims42
A method for use with a storage medium that holographically stores information, the method comprising the following steps:
- (a) generating a reconstructed data beam by directing a first coherent light beam into a storage medium, wherein the first coherent light beam reproduces a reference beam used to holographically store information in the storage medium;
- (b) obtaining a first image from a first combined beam produced by combining at least a portion of the reconstructed data beam with at least a portion of second coherent light beam, wherein the reconstructed data beam and the second coherent light beam have a phase difference that is a first phase difference;
- (c) obtaining a second image from a second combined beam produced by combining the reconstructed data beam with the second coherent light beam, wherein the phase difference of the reconstructed data beam and the second coherent light beam has been adjusted to produce a second phase difference;
- (d) processing the first image and second image to obtain first image contrast information and second image contrast information;
- (e) obtaining combined information from the first image and second image using the first image contrast information and the second image contrast information;
- and
- (f) processing the combined information to obtain the information holographically stored by the storage medium.
4 more elements
A system for use with a storage medium that holographically stores information, the system comprising:
- a light source which generates a first coherent light beam that is a reproduction of a reference beam used in holographically storing information in a storage medium and wherein the first coherent beam generates a reconstructed data beam from the storage medium;
- a beam combiner which combines at least a portion of the reconstructed data beam with at least a portion of a second coherent light beam to produce a combined beam;
- a camera which captures an image from the combined beam;
- a phase retarder which causes a first phase difference and a second phase difference between the reconstructed data beam and the second coherent beam;
- and
- a processor which (a) directs the phase retarder to cause the first phase difference between the reconstructed data beam and the second coherent beam to obtain a first image from the camera of the combined beam when the reconstructed data beam and the second coherent beam have the first phase difference;
- (b) directs the phase retarder to cause the second phase difference between the reconstructed data beam and the second coherent beam to obtain a second image from the camera of the combined beam when the reconstructed data beam and the second coherent beam have the second phase difference;
- (c) processes the first image and second image to obtain first image contrast information and second image contrast information, (d) combines information from the first image and second image using the first image contrast information and the second image contrast information to obtain combined information;
- and (e) processes the combined information to obtain the information holographically stored by the storage medium.
6 more elements
A system for use with a storage medium that holographically stores information, the system comprising:
- means for generating a reconstructed data beam by directing a first coherent light beam into a storage medium, wherein the first coherent light beam reproduces a reference beam used to holographically store information in the storage medium;
- means for obtaining a first image from a first combined beam produced by combining at least a portion of the reconstructed data beam with at least a portion of a second coherent light beam, wherein the reconstructed data beam and the second coherent light beam have a phase difference that is a first phase difference;
- means for obtaining a second image from a second combined beam produced by combining the reconstructed data beam with the second coherent light beam, wherein the phase difference of the reconstructed data beam and the second coherent light beam has been adjusted to produce a second phase difference;
- means for processing the first image and second image to obtain first image contrast information and second image contrast information;
- and
- means for obtaining combined information from the first image and second image using the first image contrast information and the second image contrast information;
- and
- means for processing the combined information to obtain the information holographically stored by the storage medium.
5 more elements
Dependencies are inferred from the claim text.