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. 21, 2002
Filed:
Jan. 20, 1998
Kazuhisa Yamamoto, Takatsuki, JP;
Yasuo Kitaoka, Ibaragi, JP;
Ayumu Tsujimura, Osaka, JP;
Masahiro Kume, Otsu, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
Laser light emitted from the wavelength-locked GaN semiconductor laser is collimated through a collimation lens, led through a polarization beam splitter and a ¼ wavelength plate, and converged by a focus lens so as to be radiated on pits formed in an optical disk medium. The signal light from the optical disk medium is collimated by the focus lens, and has its polarization direction turned by the ¼ wavelength plate by 90° relative to its polarization direction before being returned from the optical disk medium. As a result, the signal light is reflected from the polarization beam splitter so as to be converged on the optical detector by the focus lens.