OPTICAL PICKUP APPARATUS

Title:

OPTICAL PICKUP APPARATUS

Document Type and Number:

WIPO Patent Application WO/1996/004649

Kind Code:

A1

Abstract:

Since an S-polarized laser beam sent out from a laser diode is ordinary ray with respect to an optical element having birefringent characteristics, it enters a quarter-wave plate with its optical path not changed. The quarter-wave plate turns this laser beam into circularly polarized light. An objective lens condenses the laser beam of circularly polarized light on a signal recording surface of a disk. The return light reflected on the signal recording surface of the disk enters the quarter-wave plate again through the objective lens. The quarter-wave plate turns this incident return light into P-polarized light. A laser beam of this P-polarized light becomes abnormal light with respect to an optical element (2) having birefringent characteristics. The optical element having birefringent characteristics changes the optical path of the P-polarized laser beam, the abnormal light. Accordingly, the return light from the disk does not return to the laser diode but to a light condensing surface of a photodetector.

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Inventors:

EGUCHI NAOYA (JP)
WIECHMANN WERNER (JP)

Application Number:

PCT/JP1995/001511

Publication Date:

February 15, 1996

Filing Date:

July 28, 1995

Export Citation:

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Assignee:

SONY CORP (JP)
EGUCHI NAOYA (JP)
WIECHMANN WERNER (JP)

International Classes:

G11B7/12; G11B7/135; G11B11/105; G11B7/125; (IPC1-7): G11B7/135

Foreign References:

JPH0329129A	1991-02-07
JPH0438631A	1992-02-07
JPS63291238A	1988-11-29

Other References: