Laser power calibration by measuring laser drive current at out of focus and in focus conditions
US5216659A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 1991 |
| Grant date | Jun 1, 1993 |
| Priority date | — |
| Expiry date | Sep 11, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/126
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.