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:
Jan. 27, 2009
Filed:
Feb. 17, 2005
Teiichiro Oka, Tokyo, JP;
Yoshinori Sato, Tokyo, JP;
Teiichiro Oka, Tokyo, JP;
Yoshinori Sato, Tokyo, JP;
TDK Corporation, Tokyo, JP;
Abstract
Beams of light emitted from a light source are incident on a polarizer. The direction of a transmission axis of the polarizer can be adjusted in advance such that the polarizer transmits P polarized light, and S polarized light is attenuated. Beams of light transmitted through a diffracting device and a collimator lens for incidence on a beam splitter are made up substantially only by P polarized light. Part of the beams of light, which is reflected on the beam splitter, is incident on a photodetector for feedback control of outputs from the light source. Since S polarized light is attenuated by the polarizer, only P polarized light is incident on the photodetector. Consequently, if the quantity of emitted laser beams changes, a ratio between the quantity of light for record and reproduction and the quantity of light for APC remains substantially constant, thereby increasing accuracy of detecting the intensity of laser beams, to avoid errors in record and reproduction.