Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2005-04-19
2005-04-19
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S044410, C369S112120, C369S044320, C369S053280
Reexamination Certificate
active
06882599
ABSTRACT:
An optical pickup device has a semiconductor laser for emitting a light beam, a hologram, a light-concentrating optical system, a collimation lens and a measuring unit for measuring quantity of light. The hologram generates a first light beam by splitting the light beam, which has passed through the light-concentrating optical system, along a first straight line that is perpendicular to the optical axis of the light beam and serves as a boundary, and then guides the light beam to the measuring unit. The measuring unit is provided with photosensors, which are provided linearly symmetrical each other with respect to an axis of symmetry of a straight line that extends through the optical axis of the first light beam and corresponds to the first straight line and arranged in positions located apart from the optical axis of the first light beam. An aberration signal is detected by a difference between electric signals from two of the photosensors. By measuring and correcting the spherical aberration of a light-concentrating optical system, the optical pickup device records and reproduces information on each information recording layer of a multi-layer optical disk even when a cover glass thickness error, a lens interval error and a lens thickness error exist.
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Agustin Peter Vincent
Conlin David G.
Edwards & Angell LLP
Miller Brian E.
Sharp Kabushiki Kaisha
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