Patent Number: 7,085,218

Title: Optical head device and optical information recording or reproducing device

Abstract: In an optical head device and an optical information recording/reproducing device using the optical head device, by driving a liquid crystal panel 4a, the liquid crystal panel 4a produces wave aberration for light on a going path and light on a returning path likewise. Accordingly, when the substrate-thickness deviation or tilt of the disc 7 is corrected, the wave aberration due to the substrate-thickness deviation or tilt of the disc 7 and the wave aberration produced by the liquid crystal panel 4a are canceled by each other for both of the light on the going path and the light on the returning path, so that no wave aberration remains for the light on the returning path and the phase distribution is not varied.

Inventors: Katayama; Ryuichi (Tokyo, JP)

Assignee: NEC Corporation

International Classification: G11B 7/00 (20060101)

Expiration Date: 8/01/02018