Phase changing recording medium with amorphous points each formed by a pair of high power and low recording pulses

摘要

A spatially-independent N amorphous point train is formed by pulse width modulation of a laser to record information in a sample-servo optical disk drive used for a personal computer. Amorphous points are each formed by a pair of a high-power recording pulse WH and a lower power recording pulse WL for rewrite, conducted together with erasing of previous information by pairs of a high-power erasing pulse EH and a lower power erasing pulse EL with power relationships enabling integration of power per pulse of WH and WL with respect to time to substantially equal integration of power of EH and EL with respect to time, and control of recording pulse power such that a high-power level WH1 for all but a leading amorphous point is greater than a high-power level WH2 of the leading amorphous point, so that a low power level WL1 of all but a trailing amorphous point is less than a low power level WL2 of the trailing amorphous point. The time width of the high-power recording pulse is substantially equal to a time width of the lower power recording pulse and a time width of the high-power erasing pulse is substantially equal to a time width of a lower power erasing pulse. Laser power is adjusted in accordance with a power change from start to end of a train and in accordance with a recorded test pattern, periodically.