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:
Feb. 07, 2006
Filed:
Sep. 12, 2002
Mizuki Nakamura, Iwata-gun, JP;
Atsushi Kitamura, Iwata-gun, JP;
Kozo Matsumoto, Iwata-gun, JP;
Motoji Egawa, Iwata-gun, JP;
Mizuki Nakamura, Iwata-gun, JP;
Atsushi Kitamura, Iwata-gun, JP;
Kozo Matsumoto, Iwata-gun, JP;
Motoji Egawa, Iwata-gun, JP;
Minebea Co., Ltd., Kitasaku-Gun, JP;
Abstract
A laser beam emitted from a laser diode and having a wavelength of 780 nm is S-polarized. A polarization plane rotating means (λ/4 phase plate) is disposed between a super-resolution cut-off filter comprising a polarizing filter film and an objective lens. When reading on DVD, the objective lens, the polarization plane rotating means and the super-resolution cut-off filter in combination are set to the optical path. The S-polarized laser beam is focused to a micro spot diameter by super-resolution effects by the super-resolution cut-off filter together with the objective lens. Also, the S-polarized laser beam reflected at a disk and traveling backward along the incoming optical path is converted into a P-polarized laser beam while passing backward through the polarization plane rotating means. The P-polarized laser beam passes through the super-resolution cut-off filter without loss is received by a photo-detector.