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:
Mar. 11, 1997
Filed:
Jan. 24, 1994
Chiaki Sato, Tokyo, JP;
Olympus Optical Co., Ltd., Tokyo, JP;
Abstract
Light emitted from a semiconductor laser is collimated by a collimator lens into a parallel beam. The parallel beam enters a phase plate which provides a phase difference of .pi. to a half of the beam. The beam, which has passed through the phase plate, enters an objective lens and is converged onto an optical disc. The optical disc has a number of mark sets along the track, each mark set comprising optically detectable two marks. The beam from the optical disc is collected into the objective lens and is reflected by a polarized beam splitter into a light detector. The output from a light-element of the light detector is delivered to a differential amplifier and a summing amplifier. The outputs from the differential amplifier and summing amplifier are input to a divider. The output from the divider is delivered to an information reproducing unit. The information reproducing unit reproduces information recorded on the optical disc on the basis of the input, and outputs the reproduced information.