The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 06, 1992
Filed:
May. 17, 1991
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Abstract
A pickup apparatus for a magneto-optical recording medium comprises a 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 waveguide for introducing the reflected light beam into the waveguide in a TE or TM guided mode and converging the thus guided optical waves at two positions spaced from each other. First and second photodetectors are mounted on the waveguide for detecting the optical waves converged by the first and second 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 the output of the first photodetector and/or the output of the second photodetector. In another embodiment, three focusing grating couplers are disposed on two waveguides.