Method and apparatus for aberration correction
AssigneeFujitsu Limited
InventorMichio Matsuura
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Abstract
In a method and an apparatus for aberration correction according to the invention, aberration occurring in recording/reproducing information derived from causes such as thickness variation of a substrate, a tilt, a focus error and a tracking error is detected, and the aberration is corrected by correcting these causes.
Claims23
A method of correcting aberration occurring in recording/reproducing information by using reflected light of a light beam irradiating an optical recording medium, comprising the steps of:
- detecting aberrations derived from each of various causes on the basis of brightness distribution in interference areas formed by diffraction light of the reflected light;
- and
- correcting aberration occuring in recording/reproducing information by correcting the respective causes in accordance with the detected aberrations.
A method of correcting aberration occurring in recording/reproducing information by using reflected light of a light beam irradiating an optical recording medium, comprising the steps of:
- detecting an aberration derived from a relative tilt between the light beam and the optical recording medium on the basis of brightness distribution in interference areas formed by diffraction light of the reflected light;
- and
- correcting aberration occurring in recording/reproducing information by correcting the tilt in accordance with the detected aberration.
A method of correcting aberration occurring in recording/reproducing information by using reflected light of a light beam irradiating an optical recording medium, comprising the steps of:
- detecting an aberration derived from a focus error on the basis of brightness distribution in interference areas formed by diffraction light of the reflected light;
- and
- correcting aberration occurring in recording/reproducing information by correcting the focus error in accordance with the detected aberration.
A method of correcting aberration occurring in recording/reproducing information by using reflected light of a light beam irradiating an optical recording medium, comprising the steps of:
- detecting an aberration derived from thickness variation of a substrate included in the optical recording medium on the basis of brightness distribution in interference areas formed by diffraction light of the reflected light;
- and
- correcting aberration occurring in recording/reproducing information by correcting the aberration derived from thickness variation of the substrate through focus control in accordance with the detected aberration.
An apparatus for correcting aberration occurring in recording/reproducing information by using reflected light of a light beam irradiating an optical recording medium, comprising:
- at least one photodetector for detecting aberrations derived from each of various causes on the basis of brightness distribution in interference areas formed by diffraction light of the reflected light;
- and
- a correcting part for correcting the respective causes on the basis of the detected aberrations.
An apparatus for correcting aberration occurring in recording/reproducing information in or from tracks of an optical recording medium by using reflected light of a light beam irradiating the optical recording medium, comprising:
- an objective lens for converging the light beam;
- an actuator for three-dimensionally moving the objective lens;
- and
- an aberration correcting part receiving the reflected light, for detecting aberrations derived from each of various causes and for correcting the respective causes,
- wherein the aberration correcting part includes:
- at least one photodetector which receives the reflected light dividedly along a direction corresponding to a track crosswise direction, and outputs aberration detection signals corresponding to the respective causes generated by calculating with brightness of the divided light;
- and
- at least one controller selected from a tilt controller which receives a first aberration detection signal corresponding to a relative tilt between the optical recording medium and the light beam and corrects the tilt on the basis of the first aberration detection signal, a thickness/focus controller which receives a second aberration detection signal corresponding to thickness variation of a substrate included in the optical recording medium and a focus error and corrects the thickness variation of the substrate and the focus error on the basis of the second aberration detection signal, and a tracking controller which receives a third aberration detection signal corresponding to a tracking error and corrects the tracking error on the basis of the third aberration detection signal.
Dependencies are inferred from the claim text.