Pickup apparatus for magneto-optical recording medium

Details Pickup apparatus for magneto-optical recording medium Pickup apparatus for magneto-optical recording medium

1988-02-01

1989-05-23

Tupper, Robert S.

Dynamic magnetic information storage or retrieval

Head

Read only detector using light for reading magnetically...

369 13, 369 44, 369 45, 369 46, G11B 7135, G11B 1110

Patent

active

048335614

ABSTRACT:
A pickup apparatus for a magneto-optical recording medium comprises an optical waveguide for receiving a light beam reflected by a magneto-optical recording medium, and first and second focusing grating couplers disposed side by side on the optical waveguide for introducing the reflected light beam into the optical waveguide by exciting the same guided mode, and converging the guided optical waves. A third focusing grating coupler is disposed for introducing the reflected light beam into the optical waveguide in a different guided mode and converging the guided optical wave. First, second and third photodetectors are secured to the optical waveguide for respectively detecting the optical waves converged by the first, second and third focusing grating couplers. Tracking error and focusing error are detected based on the outputs of the first and second photodetectors, and recorded signals are detected based on a difference between the output of the first and/or second photodetector and an output of the third photodetector.

REFERENCES:
patent: 4165519 (1979-08-01), Goto
patent: 4358200 (1982-11-01), Heemskerk et al.
patent: 4498159 (1985-02-01), Daimon
patent: 4532522 (1985-07-01), Tsunoda et al.
patent: 4633450 (1986-12-01), Gueugnon
patent: 4733065 (1988-03-01), Hoshi et al.
patent: 4785438 (1988-11-01), Mizunde

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