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:
Feb. 12, 2008
Filed:
May. 31, 2006
Seiji Nishino, Osaka, JP;
Hidenori Wada, Uji, JP;
Yoshiaki Komma, Hirakata, JP;
Sadao Mizuno, Ibaraki, JP;
Keiichi Matsuzaki, Ikeda, JP;
Seiji Nishino, Osaka, JP;
Hidenori Wada, Uji, JP;
Yoshiaki Komma, Hirakata, JP;
Sadao Mizuno, Ibaraki, JP;
Keiichi Matsuzaki, Ikeda, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical head device includes a focusing optical system for focusing a laser beam emitted from a semiconductor laser light source on an optical information medium with an objective lens. A chromatic aberration correction element for correcting chromatic aberration occurring in the objective lens is provided between the semiconductor laser light source and the optical information medium. A light distribution correction element in which the transmittance increases with the distance from the center of the aperture surface of the objective lens is provided so as to correct a reduction of the intensity of the light incident on the aperture surface of the objective lens with the distance from the center of the aperture surface.