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:
Dec. 08, 1987
Filed:
Mar. 18, 1985
Charles W Reno, Cherry Hill, NJ (US);
RCA Corporation, Princeton, NJ (US);
Abstract
An optical system is described for use in processing information on a surface of an erasable record disc. The system decreases erasure time by forming an elongated spot from the generally circular cross section of a collimated laser beam so as to provide increased illumination time to an area recorded on the disc. The system includes a source of collimated light having a generally circular cross section, a cylindrical lens for focusing one aspect of the collimated light at a finite distance f, and a beam expander having the principal plane of its input lens at the distance f from the cylindrical lens, where the light forms a beam waist. An objective lens focuses the expanded elongated beam to a diffraction spot on the surface of the record disc. A linear actuator, such as a voice coil, responds to a control signal to position the cylindrical lens in the path of the collimated light beam for the erasing process, or out of the light path for the recording process.