Abstract: A system to monitor write power calibration values in an optical drive to detect media and lens contamination, and take appropriate remedial action when contamination is found. A laser device writes data to an optical medium housed in the optical drive by imparting a laser beam upon the medium. The laser device provides the laser beam with a level of output power selected in accordance with a W/C value. A controller generates and repeatedly updates the W/C value, and provides it to the laser device. The controller samples the W/C value at selected times, and compares it to a predetermined value. If the W/C value exceeds the predetermined value, the controller executes a specific operational sequence. For example, the controller may issue a contamination warning. When the W/C value exceeds a second predetermined value, the controller may logically write-protect the optical medium, or shift the medium to another optical drive.

Abstract: A magnetooptical disk has two axially space-apart translucent recording layers. Each translucent recording layer is axially closer to an outer surface of the disk than to the other recording layer. This geometry enables closely axially disposing a magnetic field biasing means to each of the recording layers from opposite axial sides of the disk, respectively. Laser beams are axially introduced into the disk to pass through one of the translucent recording layers in a defocussed state to reach a second recording layer in a focussed state. In this manner, recording in the second layer is effected by a modulated magnetic bias field using a constant intensity laser beam. Two sets of laser beams and magnetic biasing means are provided for recording on both data in both of the recording layers.

Abstract: An apparatus and method are provided for tracking the number of permanent and temporary errors, and spare sectors used as a result of the errors, on a per disk and per drive basis. During read/write operations, a determination is made as to whether the number of spares used to replace defective sectors on a disk, together with the number of spares used to replace defective sectors during formatting, exceeds a predetermined limit. This limit can be different depending upon the type of disk in use, rewritable or WORM. If the limit is exceeded, diagnostics are executed to ascertain the cause of the excess usage and appropriate corrective action, such as requesting that the disk and drive lens be cleaned, is initiated. Moreovers, an attempt can be made to recover used spare sectors on a rewritable disk.

Abstract: A magnetooptical disk has two axially space-apart translucent recording layers. Each translucent recording layer is axially closer to an outer surface of the disk than to the other recording layer. This geometry enables closely axially disposing a magnetic field biasing means to each of the recording layers from opposite axial sides of the disk, respectively. Laser beams are axially introduced into the disk to pass through one of the translucent recording layers in a defocussed state to reach a second recording layer in a focussed state. In this manner, recording in the second layer is effected by a modulated magnetic bias field using a constant intensity laser beam. Two sets of laser beams and magnetic biasing means are provided for recording on both data in both of the recording layers.