Calibration of write-once disks using a single disk sector

Abstract

A write-once read-many (WORM) optical disk recorder automatically calibrates its laser to emit a laser beam of a desired power level. While writing data to the WORM disk, a laser test signal is written to a laser checking area termed Automatic Laser Power Correction (ALPC) field. If the emitted laser test signal has a power level outside an acceptable power level window, then inappropriate laser power is indicated. Then, in an error recovery procedure (ERP) the laser power is calibrated in the data sector to be written to using short spaced-apart laser test signals. After successful calibration, data are written to the sector. The test signals appear as burst errors that can be corrected by a suitable error correction code. If such calibration is not successful then a write calibrate sector, WCS, is created and used for an extensive automatic calibration. In the WCS both laser power level is calibrated. The calibration result information is written to WCS for later use. A WCS may be created by command from a controller or attaching host for calibrating the laser and its control circuits in a WORM disk device. The WCS can also be written as a part of an ERP initiated by an unsuccessful write operation in one or more target sectors. Such initiation is based upon a determination that an inappropriate write power level may have been used in the attempted data writing.