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. 20, 1992
Filed:
Dec. 04, 1991
Charles W Reno, Cherry Hill, NJ (US);
General Electric Company, Philadelphia, PA (US);
Abstract
Apparatus for correcting spherical aberration of light reflected from a surface of an information-bearing layer of an optical disk and traversing through a substantially transparent substrate layer, overcoating the information layer, prior to traversal of a multi-element objective lens means, uses a correction lens assembly having several lens elements, with a variable air gap between the adjacent surfaces of a sequential pair of the lens elements. Information about the nominal thickness of an optical disk from which optical energy is then being reflected is obtained, and used to adjust the thickness of the air gap, to correct the additional spherical aberration caused by the change in covering substrate thickness and change the definition of the corrected spot to approach the definition of a spot obtained with a covering substrate of exactly the nominal value.