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:
Jun. 18, 2002
Filed:
Sep. 21, 1998
Edward C. Gage, Apple Valley, MN (US);
Ronald Evan Gerber, Richfield, MN (US);
Seagate Technology LLP, Scotts Valley, CA (US);
Abstract
The present invention is an apparatus for generating the focus, tracking, and data signals for a magneto-optical data storage device, using a Wollaston prism and a photodetector having four subdetectors. A reflected beam from a disk is directed into the Wollaston prism and is split into two beams, with the beams oriented substantially parallel to the in-track direction. The beams from the prism are collected asymmetrically by both subdetectors of first and second pairs of subdetectors, so that one subdetector in each pair collects more light than the other, and two diagonally opposite subdetectors receive more light than the other two subdetectors. Two focus composite signals are generated by adding the signals from diagonally opposite subdetectors, and the focus error signal is generated by subtracting one focus composite signal from the other. Two tracking composite signals are generated by adding the signals from adjacent subdetectors such that one subdetector is in the first pair and the other is in the second pair, and the tracking error signal is generated by subtracting one tracking composite signal from the other. Two magneto-optical composite signals are generated by adding the signals from the subdetectors of the first and second pair, respectively, and the magneto-optical data signal is generated by subtracting one magneto-optical composite signal from the other. The reflectivity data signal is generated by adding the signals from both pairs of subdetectors.