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:
Apr. 12, 2011
Filed:
Mar. 02, 2009
Yasuyuki Sugi, Ibaraki, JP;
Mitsuhiro Miyauchi, Ibaraki, JP;
Mitsuru Ito, Ibaraki, JP;
Naofumi Ueda, Ibaraki, JP;
Yasuyuki Sugi, Ibaraki, JP;
Mitsuhiro Miyauchi, Ibaraki, JP;
Mitsuru Ito, Ibaraki, JP;
Naofumi Ueda, Ibaraki, JP;
Hitachi Maxell, Ltd., Ibaraki-shi, JP;
Abstract
An object of the invention is to provide a plastic objective lens having a good lens tilt property in both thicknesses of a two-layer disc in a used temperature range even in the plastic objective lens in which a numerical aperture (NA) is equal to or higher than 0.81, while dissolving the problem mentioned above. The objective lens includes a point at which a third order comma aberration amount generated at a time of a lens tilt of the objective lens becomes equal to a third order comma aberration amount generated at a time when a disc is tilted at the same angle amount as the lens tilt angle, in a transparent board thickness which is thicker than a larger thickness of the two-layer transparent board under a room temperature (25±3° C.).