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:
Apr. 03, 2001
Filed:
Jan. 08, 1999
Hsi-Fu Shih, Chang-Hua Hsien, TW;
Tzu-Ping Yang, Taipei, TW;
Mark O. Freeman, San Mateo, CA (US);
Jinn-Kang Wang, Taipei Hsien, TW;
Industrial Technology Research Institute, Hsinchu, TW;
Abstract
A dual-wavelength holographic laser module is provided. The dual-wavelength holographic laser module includes a holographic optical element (HOE), a multiple-element photodetector, and a laser light source that can produce a laser light with a wavelength that has, for example, two desired quantities. The laser light emitted from the laser light source with a desired wavelength can travel through the HOE and an objective lens unit, which is used to focus the laser light onto an optical disk of the DVD system, the CD system, or the CD-R system, depending on which wavelength quantity is chosen. The objective lens unit includes a single lens with a changeable NA quantity or a two-lens system that can be switched to put one lens at a time in the optical path. The optical disk reflects the laser light back to the HOE along the same light path. The reflected laser light is diffracted by the HOE to reach to the multiple-element photodetector. The photodetector receives the reflected laser light to obtain a signal, which is used for focusing and tracking, and further reads the information in the DVD system, the CD system, or the CD-R system. The laser light has a single light path even though the laser light can have two different wavelength quantities.