Optical disk recording device using two modulated laser beams for recording information data

摘要

An optical disk data storage system uses two lasers to write data on the disk, preferably using pulse width modulation (PWM). The lasers direct two independently controllable laser beams to the disk to form two spots that are spaced apart a fixed distance along the data track. Each laser is independently controlled by a modulator that causes the laser to emit the laser beam in a highly pulsed manner. The two laser beams can be simultaneously and independently pulsed along a single track and each beam may be pulsed on any given write clock period and at any of several different power levels. The pulsed lasers write spots of substantially the same size on the disk. The PWM run lengths are recorded on the disk as marks comprising either a single isolated spot or a series of contiguous or overlapping spots. The pulsing of the two lasers is synchronously interleaved so that either adjacent marks (mark-interleaved writing) or adjacent mark edges (edge-interleaved writing) are alternately written by the two lasers. In this manner, an amount of time elapses between the writing of successive marks or mark edges, thereby significantly reducing the effect of thermal buildup by allowing time for the data layer in the optical disk to cool.