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:
Jan. 29, 2002
Filed:
Jan. 14, 2000
Fuji Photo Optical Co., Ltd., Saitama, JP;
Abstract
A luminous flux diameter variable type objective lens having a wavelength selectivity is disposed within a luminous flux. Arranged on a surface of the lens are a first region with no diffraction gratings, and a second region with diffraction gratings. The diffraction gratings each having a rectangular cross section are linearly arranged in the second region . The thickness (height) h of the diffraction grating A is set to such a value that the ratio of ± first-order diffracted light becomes much greater for the light having a wavelength of 780 nm used for CD-R, whereas the ratio of zero-order diffracted light becomes substantially 100% for the light having a wavelength of 635 nm used for DVD.