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:
Nov. 23, 2004
Filed:
Nov. 14, 2001
Applicant:
Inventors:
Hiroyuki Tadano, Kitakatsuragi-gun, JP;
Ikuo Nakano, Yamatokoriyama, JP;
Assignee:
Sharp Kabushiki Kaisha, Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B 2/740 ; G11B 7/00 ;
U.S. Cl.
CPC ...
G02B 2/740 ; G11B 7/00 ;
Abstract
The focal point detection method detects focal point dislocation of a coupling objective lens in accordance with a light beam passing a 60% to 80% region of a light beam effective diameter, which is centered with respect to an optical axis OZ of a light beam passing through the coupling objective lens, and which is regulated by a numerical aperture of the coupling objective lens. In this manner, focal point dislocation of a converging optical system can be performed without an offset, thereby accurately forming a focal point of the converging optical system on an information recording layer of an optical recording medium.