Optical head and optical disk unit

Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system

Reexamination Certificate

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Details

C369S044410

Reexamination Certificate

active

10530424

ABSTRACT:
An optical head comprising a light source, an objective lens, a light splitting means, a light receiving element, a tracking error signal detection means, and a spherical aberration detection means, wherein the light splitting means has six regions that are divided by a first splitting line that is substantially parallel to a longitudinal direction of an information tracks, and by second and third splitting lines perpendicular to the first splitting line. The spherical aberration detection means compares a first focal point shift amount obtained by detecting the size of a light spot formed by focusing the light fluxes created by laser light passing through two regions that are disposed between the second and third splitting lines, onto the light receiving element, and a second focal point shift amount obtained by detecting the size of a light spot formed by focusing the light fluxes created by laser light passing through the four regions, which are disposed on the outer side of the second and third splitting lines, to generate a spherical aberration error signal for detecting the spherical aberration generated at the objective lens.

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Akihiro et al., JP-11-073658 (translation), Apr. 16, 1999, Matsushita Electric Industrial Co.
Hiroyuki et al., JP-2002-157756 (translation), May 31, 2002, Sharp Corp.

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