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:
Jan. 01, 2002
Filed:
Oct. 03, 2000
Applicant:
Inventor:
Naotaro Nakata, Kyoto, JP;
Assignee:
Rohm Co., Ltd., Kyoto, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B 5/32 ;
U.S. Cl.
CPC ...
G02B 5/32 ;
Abstract
An optical pickup includes a hologram unit. The hologram unit includes a hologram pattern formed circular by dividing into two and then joining together first and second patterns formed in the entire circular region. The first pattern is designed to minimize a sub-beam spot on a light-receiving device based on an optical path length and wavelength when a +1-order sub-beam is taken as a light source. The second pattern is designed to minimize the sub-beam spot on the light-receiving device based on an optical path length and wavelength when a −1-order sub-beam is taken as a light source.