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. 09, 1987
Filed:
Aug. 05, 1985
Applicant:
Inventor:
Donald K Cohen, Tucson, AZ (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
250201 ; 2502 / ; 369 45 ;
Abstract
An optical disk recorder focus-error system includes a so-called 'knife-edge' focus detector. The dynamic range of the detector is enlarged by placing an apertured mask intermediate the knife edge and the source of the light beam being focused. The knife-edge mask and the apertured mask can be deposited opaque films on a lens.