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:
Dec. 04, 2007
Filed:
Apr. 28, 2004
Kenichi Hayashi, Nagano, JP;
Yuji Fujita, Nagano, JP;
Yoshifusa Miyasaka, Nagano, JP;
Tetsuro Okamura, Chino, JP;
Kenichi Hayashi, Nagano, JP;
Yuji Fujita, Nagano, JP;
Yoshifusa Miyasaka, Nagano, JP;
Tetsuro Okamura, Chino, JP;
Nidec Sankyo Corporation, Nagano, JP;
Abstract
A common objective lens typically used in reading data from different optical data storage media that are responsive to laser beams of different wavelengths, such as CD and DVD is provided. The lens has a refracting surface with inner and outer refracting surface regions. Diffraction gratings are provided in both the inner and outer refracting surface regions with each having a differential optical path function. The inner diffraction grating and at least a part of the outer diffraction grating emit an order of diffracted beams which have different polarities to cancel out any spherical aberrations caused by a change in temperature.