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:
Oct. 18, 2005
Filed:
Oct. 02, 2001
Jorrit Ernst DE Vries, Eindhoven, NL;
Bernardus Hendrikus Wilhelmus Hendriks, Eindhoven, NL;
Jorrit Ernst De Vries, Eindhoven, NL;
Bernardus Hendrikus Wilhelmus Hendriks, Eindhoven, NL;
Koninklijke Philips Electronics N.V., Eindhoven, NL;
Abstract
A device for scanning a first and second type of optical record carriers () generates a first and a second radiation beam for scanning the first and second type of record carriers, respectively, the first radiation beam having a first numerical aperture larger than the second numerical aperture of the second radiation beam. The device includes a non-periodic phase structure that does not affect the first radiation beam. The phase structure introduces an amount of spherical aberration in the second radiation beam for scanning the second type of record carriers for compensating the difference in spherical aberration required for scanning through the different thickness of the transparent layer () of the first and second type of record carriers (). To reduce the amount of stray light on the detection system () from rays in the second radiation beam having a numerical aperture larger than the second numerical aperture, the phase grating introduces a discontinuity in the gradient of the wavefront deviation it introduces in the second radiation beam. The discontinuity allows spatial filtering in the plane of the detection system () of the desired and undesired rays of the second radiation beam.