Method for recording and erasing optical information.

摘要

A read/write optical disk system for performing high-density recording, reproduction and erasing of information signals by utilizing reversible structural changes between the crystalline and amorphous states of a chalcogenide glass film or the like and a recording, reproducing and erasing method therefor. In the method of this invention, during the period of recording and erasing, respectively, an exposed film area is first heated beyond its melting point to obtain a random state of its atomic arrangement and the rate of cooling from this melted state is controlled so as to obtain a recorded state or an erased state. This method is realized in the system by arranging a plurality of laser spots of different intensities and lengths in proximity to each other on the same track thereby ensuring high-quality erasing involving no danger of any incomplete erasure.