Aberration detection device and optical information recording and reproducing apparatus
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTetsuo Saimi, Shin-ichi Tanaka
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Abstract
A returning light beam emitted by a light source and reflected by an optical disk is separated by a half mirror, and partitioned and deflected at a hologram into a light beam passing a first region and a light beam passing a second region. The light beam passing the first region is received by a plurality of photo-detectors, and the aberration is detected by comparing the resulting signals. Based on the aberration detection, the aberration of an optical system can be reduced by driving an aberration correction element in real-time.
Claims24
An aberration detection device comprising:
- a radiation source for emitting a light beam;
- an object lens for focusing the light beam on an information carrier;
- a hologram for partitioning a returning light beam that has been reflected by the information carrier and passed through said object lens into a light beam passing a first region and a light beam passing a second region, and diffracting the light beam passing the first region away from said radiation source;
- and
- a plurality of light detectors for receiving a diffracted light beam passing through the first region;
- wherein said plurality of light detectors receives both a +1-order diffractive light beam and a −1-order diffractive light beam that have passed through the first region and been diffracted,
- said plurality of light detectors comprises a photo-detector partitioned into at least two portions,
- the photo-detector is arranged such that both the +1-order diffractive light beam and the −1-order diffractive light beam are irradiated onto a partition line of the at least two portions, and
- a spherical aberration, a coma aberration or an astigmatism is detected and identified individually from an output signal from the photo-detector.
An optical head device for (i) recording information onto a recordable and reproducible information carrier having a plurality of information recording layers, and an optical separation layer sandwiched between the information recording layers and/or (ii) reproducing the recorded information;
- said optical head device comprising:
- a radiation source for emitting a light beam;
- a light beam focusing system for focusing a light beam emitted by said radiation source onto at least one of the plurality of information recording layers;
- an aberration correction system for correcting an aberration of the focused light beam;
- a light beam splitter for separating a returning light beam that has been reflected by the information carrier and passed through said light beam focusing system from an incoming light beam;
- a hologram for partitioning and diffracting the returning light beam, that has been separated by said light beam splitter, into a light beam passing a first region and a light beam passing a second region;
- and
- a plurality of light detectors for receiving a diffracted light beam passing through the first region;
- wherein said plurality of light detectors receives both a +1-order diffractive light beam and a −1-order diffractive light beam that have passed through the first region and been diffracted,
- said plurality of light detectors comprises a photo-detector partitioned into at least two portions,
- the photo-detector is arranged such that both the +1-order diffractive light beam and the −1-order diffractive light beam are irradiated onto a partition line of the at least two portions, and
- a spherical aberration, a coma aberration or an astigmatism is detected and identified individually from an output signal from the photo-detector.
An optical information recording and reproducing apparatus for (i) recording information onto a recordable and reproducible information carrier having a plurality of information recording layers, and an optical separation layer sandwiched between the information recording layers and/or (ii) reproducing the recorded information;
- said optical information recording and reproducing apparatus comprising:
- a radiation source for emitting a light beam;
- a light beam focusing system for focusing a light beam emitted by said radiation source onto at least one of the plurality of information recording layers;
- an aberration correction system for correcting an aberration of the focused light beam;
- a light beam splitter for separating a returning light beam that has been reflected by the information carrier and passed through said light beam focusing system from an incoming light beam;
- a hologram for partitioning and diffracting the returning light beam, that has been separated by said light beam splitter, into a light beam passing a first region and a light beam passing a second region;
- and
- a plurality of light detectors for receiving a diffracted light beam passing through the first region;
- wherein said plurality of light detectors receives both a +1-order diffractive light beam and a −1-order diffractive light beam that have passed trough the first region and been diffracted,
- said plurality of light detectors comprises a photo-detector partitioned into at least two portions,
- the photo-detector is arranged such that both the +1-order diffractive light beam and the −1-order diffractive light beam are irradiated onto a partition line of the at least two portions, and
- a spherical aberration, a coma aberration or an astigmatism is detected and identified individually from an output signal from the photo-detector.
Dependencies are inferred from the claim text.