Optical pickup

Details Optical pickup Optical pickup

2007-02-27

2007-02-27

Tran, Thang V. (Department: 2627)

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

C369S044370, C369S044230

Reexamination Certificate

active

10512188

ABSTRACT:
An optical pickup converts a laser beam from a semiconductor laser (1) into a parallel ray with a collimator lens (2), and divides it into a main beam (30), a sub-beam (+1st order component) (31), and a sub-beam (−1st order component) (32) with a gradient multiple-division type phase difference grating (3). After passing through a beam splitter (4), an objective lens (5) condenses the light beams on a track (61) of an optical disc (6), and the reflected light that has passed through the objective lens5is reflected at the beam splitter (4) and is guided into optical detectors (8A,8B, and8C) by a condensing lens (7). Accordingly, in a tracking error signal detecting method using the push-pull signals of the main beam and sub-beams, an offset produced by an objective lens shift or a disc tilt can be cancelled at low cost without lowering the efficiency of using light.

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Ueyama et al., “A Novel Tracking Servo System for Multi-Types of DVD with Phase-Shift DPP Method,” Joint International Symposium on Optical Memory and Optical Data Storage 2002.
Ueyama et al., “A Novel Tracking Servo System for Multitypes of Digital Versatile Disks Using Phase-Shift Differential Push-Pull Method,” Appl. Phys. vol. 42 pp. 952-953 (2003).
Ueyama et al., “A New Tracking Servo System using a Phase-Shift Differential Push-Pull Method for Recordable Optical Disks,” Joint International Symposium on Optical Memory and Optical Data Storage 2003.

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