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. 29, 1991
Filed:
Oct. 19, 1988
Yoshikazu Hori, Osaka, JP;
Makoto Kato, Nishinomiya, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical pick-up device includes a semiconductor laser for emitting a laser beam, a focusing lens for focusing the laser beam emitted from the laser onto the surface of an optical medium, a holographic optical element having an anisotropic refractive index and located between the laser and the focusing lens, and a photodetector for receiving a diffracted laser beam from the holographic optical element. The holographic optical element, which may be formed of a liquid crystal or a lithium niobate crystal, transmits therethrough in an undiffracted manner the laser beam emitted from the semiconductor laser and diffracts only the reflected laser beam which has reflected off of the optical medium.