| 摘要 |
PROBLEM TO BE SOLVED: To surely cause reversible phase transition even when a recording film having a high phase transition rate is used, by forming the recording points with a single pulse or a plurality of pulses having the pulse width shorter than the period for the center of an energy beam spot passing from one end of a recording spot to the other end. SOLUTION: While an optical disk is rotated at a specified rotation rate, the laser light power is increased from a readout power level to a crystallization power level in an area for recording and then the power is varied. The power is increased for a short time to the level of amorphous transition in the region to be changed into an amorphous state according to an information signal. The time width when the laser power in increased to the amorphous level is specified to about 3/4 of the period when the center of the light spot passes from one end to the other end of the corresponding amorphous point (the region having lower crystallinity than in the surrounding area). The irradiated region of a disk is melted by irradiation of the laser light in the amorphous power level and then rapidly cooled to change into the amorphous state. |
