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. 04, 2006
Filed:
Mar. 09, 2005
Hiroaki Yukawa, Tokyo, JP;
Hiroaki Yukawa, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical head includes a light emitter/detector to emit a laser light towards an optical disc and to detect a return light from the optical disc, a diffraction grating to split the laser light into three beams, and a light converging optical system to focus the laser light on a recording surface of the optical disc. The diffraction grating has formed therein a plurality of slits formed whose depth is selected so that the efficiency of diffraction of first-order light when a first light beam is incident upon the diffraction grating is higher than that when a second light beam having a longer wavelength than the first light beam is incident upon the diffraction grating.