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. 05, 2013
Filed:
Oct. 23, 2009
Fumitomo Yamasaki, Nara, JP;
Kousei Sano, Osaka, JP;
Tomoaki Tojo, Hyogo, JP;
Katsuhiko Hayashi, Nara, JP;
Yoshiaki Komma, Osaka, JP;
Fumitomo Yamasaki, Nara, JP;
Kousei Sano, Osaka, JP;
Tomoaki Tojo, Hyogo, JP;
Katsuhiko Hayashi, Nara, JP;
Yoshiaki Komma, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An optical head, an optical disc device and an information processing device are capable of suppressing the amount of third-order astigmatism created upon recording or reproducing information on or from a multi-layer optical disc including at least three information recording surfaces. An objective lens satisfies a relationship of tc>(t+tn)/2 assuming that tdenotes the thickness of a light transmitting layer from the outer surface of the multi-layer optical disc to an information recording surface having the largest light transmitting layer thickness, tn denotes the thickness of a light transmitting layer from the outer surface of the multi-layer optical disc to an information recording surface having the smallest light transmitting layer thickness and tc denotes the thickness of a virtual light transmitting layer at which the absolute value of a third-order spherical aberration is minimum when blue-violet laser light is incident as parallel light on the objective lens.