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US 9,977,402 B2Granted
Optical information recording/reproducing apparatus, optical information recording/reproducing method
AssigneesArizona Board of Regents on Behalf of the University of Arizona, Hitachi, Ltd.
InventorsYuzuru Takashima, Kenichi Shimada
Life of this patent
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Abstract
An optical information recording/reproducing apparatus and method thereof which compensate for the effect of mechanical instability on holographic data storage. A time dependent deviation profile of an optical beam during recording is determined. The time dependent deviation profile is related to a phase profile to be applied to a reference beam during recording or reproduction of a hologram, and the related phase profile is applied to the reference beam during recording or reproduction of the hologram.
Claims15
An optical information processing apparatus for recording information in a holographic medium, the apparatus comprising:
- a laser source which generates at least one optical beam including a reference beam and a signal beam;
- a beam control device which steers an incident angle of the reference beam with respect to the holographic medium to write data in the holographic medium based on interference of the reference beam and the signal beam in the holographic medium, the beam control device comprising a Galvano mirror;
- a deviation profiler which obtains a time dependent deviation profile of the optical beam for one page of data recorded in the holographic medium at a nominally fixed angle of the incident angle of the reference beam, wherein the deviation profiler comprises a sensor which detects a time dependent deviation profile of the optical beam in the apparatus during recording of one page of data at a nominally fixed angle for the incident angle of the reference beam, the sensor detecting the time dependent deviation profile of the Galvano mirror during the recording;
- a processor programmed to relate the time dependent deviation profile to at least one of a phase profile and an amplitude profile to be applied to the reference beam;
- and
- an adaptive optical element which applies said at least one of the phase profile and the amplitude profile to the reference beam to compensate for time dependent deviations of the optical beam.
3 more elements
An optical information processing apparatus for reading information in a holographic medium, the apparatus comprising:
- a laser source which generates a reference beam;
- a beam control device which steers an incident angle of the reference beam with respect to the holographic medium to read data in the holographic medium;
- a processor programmed to relate a time dependent deviation profile, associated with an optical beam which recorded said data in the holographic medium, to at least one of a phase profile and an amplitude profile to be applied to the reference beam;
- an adaptive optical element which applies said at least one of the phase profile and the amplitude profile to the reference beam to compensate for time dependent deviations of the optical beam which occurred in the recording of said information;
- an optical reader which reads said data in the holographic medium;
- and
- wherein the processor is programmed to relate the time dependent deviation profile to said at least one of the phase profile and the amplitude profile so that the adaptive optical element follows the function ƒ(x),
- f
-
- (
- x
- )
- =
- 1
- ∫
- 0
- t
- r
-
- exp
-
- {
- j
-
-
- 2
-
- π
- λ
-
- cos
-
-
- θ
- 0
- ·
- Δθ
-
- (
- t
- )
- ·
- x
- }
-
- dt
- where θ0 is a designed incident angle of the reference beam with respect to the holographic medium, tr is the recording exposure time, Δθ(t) is a time dependent deviation of the incident angle of the reference beam from the designed incident angle θ0, λ is a wavelength of the reference beam, and x indicates a deviated position of the reference beam on an axis including the incident angle θ0.
44 more elements
An optical information processing apparatus for recording information in a holographic medium, the apparatus comprising:
- a laser source which generates at least one optical beam including a reference beam and a signal beam;
- a beam control device which steers an incident angle of the reference beam with respect to the holographic medium to write data in the holographic medium based on interference of the reference beam and the signal beam in the holographic medium;
- a deviation profiler which obtains a time dependent deviation profile of the optical beam for one page of data recorded in the holographic medium at a nominally fixed angle of the incident angle of the reference beam, wherein the deviation profiler is programmed to estimate the time dependent deviation profile from a design specification of an optical component in a path of the at least one optical beam, the deviation profiler being programmed to estimate the time dependent deviation profile from the design specification of a servomechanism of a galvanometer mirror in the path of the at least one optical beam;
- a processor programmed to relate the time dependent deviation profile to at least one of a phase profile and an amplitude profile to be applied to the reference beam;
- and
- an adaptive optical element which applies said at least one of the phase profile and the amplitude profile to the reference beam to compensate for time dependent deviations of the optical beam.
3 more elements
An optical information processing apparatus for recording information in a holographic medium, the apparatus comprising:
- a laser source which generates at least one optical beam including a reference beam and a signal beam;
- a beam control device which steers an incident angle of the reference beam with respect to the holographic medium to write data in the holographic medium based on interference of the reference beam and the signal beam in the holographic medium;
- a deviation profiler which obtains a time dependent deviation profile of the optical beam for one page of data recorded in the holographic medium at a nominally fixed angle of the incident angle of the reference beam;
- a processor programmed to relate the time dependent deviation profile to at least one of a phase profile and an amplitude profile to be applied to the reference beam;
- and
- an adaptive optical element which applies said at least one of the phase profile and the amplitude profile to the reference beam to compensate for time dependent deviations of the optical beam;
- and
- wherein the processor is programmed to relate the time dependent deviation profile to said at least one of the phase profile and the amplitude profile so that the adaptive optical element follows the function ƒ(x),
- f
-
- (
- x
- )
- =
- 1
- ∫
- 0
- t
- r
-
- exp
-
- {
- j
-
-
- 2
-
- π
- λ
-
- cos
-
-
- θ
- 0
- ·
- Δθ
-
- (
- t
- )
- ·
- x
- }
-
- dt
- where θ0 is a designed incident angle of the reference beam with respect to the holographic medium, tr is the recording exposure time, Δθ(t) is a time dependent deviation of the incident angle of the reference beam from the designed incident angle θ0, λ is a wavelength of the reference beam, and x indicates a deviated position of the reference beam on an axis including the incident angle θ0.
45 more elements
Dependencies are inferred from the claim text.