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. 01, 2003
Filed:
Oct. 03, 2001
Masato Kawabata, Saitama, JP;
Toshiaki Katsuma, Saitama, JP;
Fuji Photo Optical Co., Ltd., Saitama, JP;
Abstract
One surface of an objective lens is provided with a zonal part which acts such that the quantity of light having a wavelength of &lgr; is apparently canceled in the outer peripheral portion of the luminous flux due to an interference effect, whereas the quantity of light having a wavelength of &lgr; in the outer peripheral part is kept as it is. The zonal part has such a step that light supposed to pass a position corresponding to the zonal part if the zonal part does not exist and light passing a position at which the zonal part is formed if the zonal part exists generate therebetween a phase difference satisfying a predetermined conditional expression. The numerical aperture at a boundary position of the step has a value between two numerical apertures for the respective wavelengths &lgr; and &lgr; .