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:
Aug. 16, 2011
Filed:
Jul. 13, 2009
Takashi Nakao, Tokyo, JP;
Fumiaki Nakano, Tokyo, JP;
Noriaki Nishi, Kanagawa, JP;
Nobuhiko Ando, Tokyo, JP;
Hiroaki Nakagawa, Tokyo, JP;
Yutaka Tentaku, Tokyo, JP;
Takashi Nakao, Tokyo, JP;
Fumiaki Nakano, Tokyo, JP;
Noriaki Nishi, Kanagawa, JP;
Nobuhiko Ando, Tokyo, JP;
Hiroaki Nakagawa, Tokyo, JP;
Yutaka Tentaku, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical pickup includes: a light source that emits a light beam; an object lens that condenses the light beam on a target recording layer of an optical disk; a lens moving unit; a condensing lens; a hologram element that diffracts, in diffracting a reflected light beam and separating it into reflected zeroth-order and first-order light beams, parts of the reflected first-order light beam in a first direction and sets them as first and second beams, diffracts parts of the reflected first-order light beam in a second direction and sets them as third and fourth beams; and a photodetector that receives the first and second beams and the third and fourth beams and generates light reception signals, and receives interlayer stray light of a part of the light beam reflected by the other recording layers other than the target recording layer and generates a stray light reception signal.