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. 01, 1993
Filed:
Sep. 11, 1991
David E Call, Tucson, AZ (US);
Julian Lewkowicz, Tucson, AZ (US);
International Business Machines, Armonk, NY (US);
Abstract
Apparatus and method for calibrating the drive current circuit of a semiconductor laser diode subject to reflected optical feedback from a target surface such an an optical recording disk. The method makes use of two power output vs. drive current characteristic curves for the laser, one curve for in focus condition and one for out of focus condition, wherein the curves exhibit an asymptotic region at high power levels (P.sub.2). Measurement of drive current (I.sub.2) power level P.sub.2 is taken under an out of focus condition. Measurements of drive current at a predetermined low power level P.sub.1 are taken for both (I.sub.1) and in focus condition (I.sub.3). The linear slope of the in focus curve can thus be calculated to set desired power levels.