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:
Jun. 29, 1999
Filed:
Apr. 25, 1997
Yang-Oh Choi, Seoul, KR;
Daewoo Electronics Co., Ltd., Seoul, KR;
Abstract
A beam generated from a laser light source are reflected by a beam splitter to proceed toward an optical disc. The beam focus onto the optical disc via a selective light-transmitting part installed in front of the optical disc and an objective lens. The beam is totally transmitted through an inner circular portion of the selective light-transmitting part and half transmitted through a peripheral portion of the selective light-transmitting part. The beam transmitted through the inner circular portion forms the larger beam spot on the disc while the beam transmitted through the peripheral portion forms the smaller beam spot, so that spherical aberration to be occurred due to change of the thickness of the optical disc is minimized by using the beam with smaller numerical aperture which has transmitted through the inner circular portion of the selective light-transmitting part.