Aberration correction apparatus and method
First Claim
1. An aberration correction unit disposed in an optical path of an optical system for irradiating a recording medium with a light beam for correcting aberration produced in said light beam, said aberration correction unit comprising:
- a first electrode and a second electrode being opposed to each other; and
a liquid crystal, disposed between said first electrode and said second electrode, for producing a holographic diffraction grating effect by applying a voltage across the liquid crystal to produce a change in phase to light passing therethrough, wherein at least one of said first electrode and said second electrode is formed in a partitioned shape such that said liquid crystal produces a holographic diffraction grating effect because of the partitioned shape when applying voltages to said first electrode and said second electrode.
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Accused Products
Abstract
An aberration correction device for correcting aberration produced in a light beam, which includes: a first electrode layer and a second electrode layer being opposed to each other; and a liquid crystal disposed between the first electrode layer and the second electrode layer for producing a change in phase in a light beam passing therethrough in accordance with voltages applied to the first electrode layer and the second electrode layer. The first electrode layer is divided into a plurality of phase adjustment portions which are electrically isolated each other. Each of the plurality of phase adjustment portions includes a pair of electrodes arranged in such a form that produces an electric field distribution for correcting the aberration by applying predetermined voltages thereto.
49 Citations
20 Claims
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1. An aberration correction unit disposed in an optical path of an optical system for irradiating a recording medium with a light beam for correcting aberration produced in said light beam, said aberration correction unit comprising:
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a first electrode and a second electrode being opposed to each other; and
a liquid crystal, disposed between said first electrode and said second electrode, for producing a holographic diffraction grating effect by applying a voltage across the liquid crystal to produce a change in phase to light passing therethrough, wherein at least one of said first electrode and said second electrode is formed in a partitioned shape such that said liquid crystal produces a holographic diffraction grating effect because of the partitioned shape when applying voltages to said first electrode and said second electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
a light source for emitting said light beam;
an optical system for guiding said light beam; and
an optical detector for detecting a light beam which has been reflected by said recording medium and transmitted said aberration correction unit.
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9. An aberration correction apparatus having the optical pickup device according to claim 8, comprising:
voltage applying means for applying voltages to said first electrode and said second electrode of said aberration correction unit so that said liquid crystal produces a holographic diffraction grating effect.
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10. An aberration correction device for correcting aberration produced in a light beam of an optical system for guiding said light beam, comprising:
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a first electrode layer and a second electrode layer being opposed to each other; and
a liquid crystal disposed between said first electrode layer and said second electrode layer for producing a change in phase in a light beam passing therethrough in accordance with voltages applied to said first electrode layer and said second electrode layer, wherein said first electrode layer is divided into a plurality of phase adjustment portions which are electrically isolated from each other, each of said plurality of phase adjustment portions including a pair of electrodes arranged in a form that produces an electric field distribution for correcting said aberration by applying predetermined voltages thereto. - View Dependent Claims (11, 12, 13, 14, 15)
a determination section for determining each aberration amount of said light beam in a region corresponding to each of said plurality of phase adjustment portions;
a voltage applying section for applying each of said plurality of phase adjustment portions with voltages corresponding to each of the determined aberration amounts;
a selecting section for selecting a phase adjustment region including one or more consecutive phase adjustment portions based on each of the determined aberration amounts; and
a controller for conducting a control for changing a phase-adjustment amount in said phase adjustment region to a phase amount corresponding to an integer multiple of the wavelength of said light beam.
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16. An aberration correction apparatus for correcting aberration produced in a light beam of an optical system for guiding said light beam, comprising:
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an aberration correction device having a plurality of phase adjustment portions for producing a phase change in said light beam by an voltage applied thereto;
a phase adjustment section for applying voltage to each of said plurality of phase adjustment portions to adjust the phase;
a determination section for determining whether a phase-adjustment amount of each said phase adjustment portion exceeds a predetermined limit adjustment amount; and
a controller for changing the phase-adjustment amount of each said phase adjustment portion to a value resulting from a subtraction of a phase amount corresponding to an integer multiple of the wavelength of said light beam from the phase-adjustment amount on the basis of the result of determination made by said determination section. - View Dependent Claims (17, 18, 19)
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20. A method of correcting aberration for an aberration correction device having a plurality of phase adjustment portions for producing a phase change in a light passing through said aberration correction device to adjust the phase, comprising the steps of:
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applying a voltage to each of said plurality of phase adjustment portions to adjust the phase;
determining whether a phase-adjustment amount of said phase adjustment portion exceeds a limit adjustment amount; and
changing the phase-adjustment amount of each said phase adjustment portion to a value resulting from a subtraction of a phase amount corresponding to an integer multiple of the wavelength of said light beam from the phase-adjustment amount on the basis of the result of the determination in the determining step.
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Specification