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. 26, 2011
Filed:
Apr. 15, 2009
Takeshi Omori, Osaka, JP;
Takaaki Kassai, Osaka, JP;
Kenji Maebara, Kyoto, JP;
Keiji Fujita, Kyoto, JP;
Hiroaki Ashiwa, Ibaraki, JP;
Takeshi Omori, Osaka, JP;
Takaaki Kassai, Osaka, JP;
Kenji Maebara, Kyoto, JP;
Keiji Fujita, Kyoto, JP;
Hiroaki Ashiwa, Ibaraki, JP;
Panasonic Corporation, Osaka, JP;
Abstract
In a focus optical system for optical discs or optical disc master exposure apparatuses, a relative positional relation between a cylindrical lens and a 4-division detector in an astigmatic optical system is adjust so that an interference fringe appearing in reflected light derived from an optical disc master is made to be incident on a dead zone of the 4-division detector. Thus, an astigmatic focus servo free from effects of variations in a focus error signal due to the interference fringe is realized. As a result of this, effects of the interference fringe appearing in the reflected light derived from an optical disc or optical disc master can be suppressed.