Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2003-12-03
2009-06-02
Young, Wayne R (Department: 2627)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S112230, C369S044320
Reexamination Certificate
active
07542385
ABSTRACT:
An optical disk unit capable of correcting a spherical aberration without using special patterns is provided. Also provided is an aberration correcting method used for such an optical disk unit. An objective lens7is moved along an optical axis by a predetermined distance from an in-focus position in a first direction, and then, is moved by the predetermined distance from the in-focus position in a second direction that is opposite to the first direction. In each of the objective lens moved states, a random signal having a plurality of amplitudes and periods is reproduced from an optional area of an information recording layer12of an optical disk11.A servo circuit10extracts a specific portion having a specific amplitude or period from the reproduced random signal in each of the objective lens moved states, finds a first amplitude value and second amplitude value in the specific portions, and controls an aberration corrector6so that the difference between the first amplitude value and the second amplitude value approaches zero.
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Alunkal Thomas D
Chung Sungyeop
Meyer Jerald L.
The Nath Law Group
Victor Company of Japan , Limited
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