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:
Mar. 16, 1999
Filed:
Sep. 02, 1997
Hans Juergen Coufal, San Jose, CA (US);
Robert K Grygier, San Diego, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A device for reading data from a multi-layered optical disk includes a short coherence-length light source, a beam splitter, an adjustable mirror and an optical detector. The beam splitter is used to form first and second light beams from the short coherence-length light beam. The first light beam is then directed to the optical disk and is reflected by a data mark stored on the optical disk. The second light beam is directed along a reference beam path. The mirror is disposed along the reference beam path and reflects the second light beam back to the beam splitter. The beam splitter recombines the reflected first light beam and the second light beam after the second light beam traverses the reference beam path. The optical detector detects the data mark by constructive interference of the combined reflected first light beam and the second light beam. The position of the mirror is adjustable so that the optical path length of the reference beam path is made equal to the optical path length of the first light beam to each layer of the multi-layered optical disk. A device for recording data onto a multi-layered optical disk uses similar components and techniques for recording data.