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. 13, 2012
Filed:
Feb. 19, 2008
Masahisa Shinoda, Tokyo, JP;
Daisuke Matsubara, Tokyo, JP;
Kenya Nakai, Tokyo, JP;
Hironori Nakahara, Tokyo, JP;
Masahisa Shinoda, Tokyo, JP;
Daisuke Matsubara, Tokyo, JP;
Kenya Nakai, Tokyo, JP;
Hironori Nakahara, Tokyo, JP;
Mitsubishi Electric Corporation, Tokyo, JP;
Abstract
An optical pickup with a simplified structure in which, according to the type of optical disc, diffracted light from three types of laser light can be directed efficiently onto a photodetector and appropriate focus control can be performed based on the signals detected by the photodetector, and a diffractive optical element that can be used in the optical pickup, which has a semiconductor laserthat can emit three types of laser light, a diffractive optical elementthat diffracts the laser light reflected from the optical disc, and a single photodetectorthat detects the diffracted light exiting the diffractive optical element. The diffractive optical elementis structured so that 0-order light is the maximal component of the diffracted light generated from each of two of three types of laser light, the two having close wavelengths (with a small wavelength difference), and +1-order light or −1-order light is the maximal component of the diffracted light generated from the remaining one type of laser light.