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. 16, 2008
Filed:
Apr. 18, 2003
Kousei Sano, Osaka, JP;
Yoshiaki Komma, Hirakata, JP;
Hidenori Wada, Uji, JP;
Akihiro Yasuda, Katano, JP;
Kousei Sano, Osaka, JP;
Yoshiaki Komma, Hirakata, JP;
Hidenori Wada, Uji, JP;
Akihiro Yasuda, Katano, JP;
Panasonic Corporation, Osaka, JP;
Abstract
The present invention provides a first light source () that emits light of a first wavelength, that at least either records onto or reproduces information from an information recording medium (), a light source () that emits light of a second wavelength that records onto or reproduces information from an information recording medium (), a light source () that emits light of a third wavelength that records onto or reproduces information from an information recording medium (), focusing means, an optical element () that passes light of the first wavelength and diffracts light of the second and third wavelengths, wherein the optical element () is an optical element in which grooves are formed in a substrate, wherein the expression:380 nm≦(−1)×420 nmis satisfied, where n is a refractive index of the substrate at a wavelength of 400 nm, and d (nm) is a depth per step of the grooves, and wherein the grooves are formed in two steps of depth d and depth