Monitoring and adjusting laser write power in an optical disk recorder using pulse-width modulated power level checking signals
US5450383A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 1995 |
| Grant date | Sep 12, 1995 |
| Priority date | — |
| Expiry date | Jan 13, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/126
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A write-once optical disk data recorder automatically calibrates a laser during a write data operation and using write pulses focussed to a disk. First, the laser is calibrated using a non-focussed laser beam. Each sector of the disk has a laser checking or test area, such as an automatic laser power correction field (ALPC) of two byte lineal extent. During a first write operation after a power up or disk load, a pulse width modulated (PWM) laser test signal is recorded using a laser power level set using the non-focussed laser beam and an indicated desired recording power level on the disk. The recorded laser test signal is read back. The length of the read back laser test signal is measured. The measured length is then compared with a desired length of the PWM laser test signal that indicates a desired laser power level. That is, as laser recording power levels increase, a resultant recorded signal grows in size. This property is used to measure laser power for calibrating laser operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.