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:
May. 31, 2005
Filed:
Aug. 30, 2001
Junji Tominaga, Tsukuba, JP;
Takashi Nakano, Tsukuba, JP;
Nobufumi Atoda, Tsukuba, JP;
Akira Sato, Shiga-ken, JP;
Manami Kuiseko, Kyoto, JP;
Takashi Kikukawa, Tsukuba, JP;
Junji Tominaga, Tsukuba, JP;
Takashi Nakano, Tsukuba, JP;
Nobufumi Atoda, Tsukuba, JP;
Akira Sato, Shiga-ken, JP;
Manami Kuiseko, Kyoto, JP;
Takashi Kikukawa, Tsukuba, JP;
National Institute of Advanced Industrial Science and Technology, Tokyo, JP;
Minolta Co., Ltd., Osaka, JP;
TDK Corporation, Tokyo, JP;
Abstract
An apparatus for reproducing information stored in an optical recording medium which comprises marks or pits which are arranged at a pitch less than λ/2NA, wherein λ is a wavelength of light used for reproduction and NA is an numerical aperture of an objective lens. The apparatus generally comprises a laser diode, a polarization beam splitter, an objective lens, beam splitters, a low-frequency light detecting system with a photodetector, a high-frequency light detecting system with a photodetector, and a signal processing circuit for combining detection signals from the photodetectors. In the high-frequency light detecting system, before a convergent lens, a shielding band is provided so as to shield the middle of a bundle of rays of reproduction light.