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. 09, 2002
Filed:
Jul. 13, 2000
Hsi-Fu Shih, Chang-Hua Hsien, TW;
Jau-Jiu Ju, Chutung Hsinchu, TW;
Tzu-Ping Yang, Taipei, TW;
Wei-Chih Lu, Tainan, TW;
Mark O. Freeman, San Mateo, CA (US);
Der-Ray Huang, Hsinchu, TW;
Carl Y. Yang, Chutung Hsinchu, TW;
Industrial Technology Research Institute, Hsinchu, TW;
Abstract
The present invention discloses a multiple-beam holographic optical pick-up head, which has the advantages of the multiple-beam optical pick-up head and the holographic optical pick-up head and can increase the light usage efficiency. This invention uses the property that a polarized diffractive optical element can generate different optical effects for laser beam with different polarizations and places a polarized multiple-beam grating and polarized hologram on the optical path for splitting the incident light toward the disc into multiple reading beams by the multiple-beam grating. The returning laser beams reflected from the disc are diffracted and diverted by the hologram to reach a photodetector. Both the incident and reflective beams are diffracted once only; thus the light usage efficiency can be increased.