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:
Jul. 10, 1984
Filed:
Sep. 23, 1980
Hiroshi Ohki, Kanagawa, JP;
Chiaki Kojima, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical reproducing head for reproducing an information signal recorded on an optical record medium includes a semiconductor laser for generating a laser beam, a first off-axis hologram lens irradiated with the laser beam from the semiconductor laser to produce a beam of parallel rays of light that has an optical axis which is off-set with respect to the optical axis of the laser beam, a second off-axis hologram lens irradiated with the beam of parallel rays of light from the first off-axis hologram lens to generate a focused beam which has an optical axis which is off-set with respect to the optical axis of the beam of parallel rays of light and has an optical axis perpendicular to the optical record medium, and a photo-detector detecting the intensity of a non-diffracted wave beam from the first off-axis hologram lens means, the non-diffracted wave beam being at least part of the focused beam which has been reflected from the optical record medium and has been diffracted by the second off-axis hologram lens. The output of the photodetector is used to produce a focus error signal and a tracking error signal for controlling the focus servo and tracking servo operations.