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:
Dec. 07, 2010
Filed:
Jul. 17, 2007
Sumito Nishioka, Nara, JP;
Nobuo Ogata, Nara, JP;
Ikuo Nakano, Nara, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An optical pickup includes: a first projector for projecting a first light beam of a first wavelength so as to record and reproduce information with respect to an optical disk having a first light transmissive layer; a second projector for projecting a second light beam of a second wavelength longer than the first wavelength so as to record and reproduce information with respect to an optical disk having a second light transmissive layer; an objective lens common to the first and second light beams; and a diffraction optical element made of a lens with a diffraction grating and a refracting face and disposed in an optical path between the first and second projectors and the objective lens. The diffraction optical element is set to satisfy a predetermined equation. As a result, an optical pickup is realized that uses a single focusing means to focus light beams of different wavelengths, so as to record and reproduce information with respect to different kinds of optical disks (recording media) respectively having light transmissive layers of different thicknesses and respectively using different optimum wavelengths of light for reproducing.