OPTICAL DISK AND METHODS FOR RECORDING AND REPRODUCING ESSENTIAL INFORMATION OF OPTICAL DISE

摘要

An optical disc and methods for recording essential information in and reproducing essential information from an optical disc are provided. The optical disc includes as a pattern of crystalline and amorphous marks storing essential information. The essential information recording method involves: heating an amorphous recording layer above the temperature of crystallization by radiating a beam according to a photoelectrically converted signal; and slowly cooling the heated recording layer to the temperature of crystallization or below to form a pattern of crystalline and amorphous marks. The essential information reproducing method involves: radiating a beam onto a pattern of crystalline and amorphous marks in which essential information of the optical disc is recorded; receiving the beam reflected from the pattern of crystalline and amorphous marks and photoelectrically converting the received beam to detect a signal; filtering the detected signal through a high-pass filter; and reproducing the essential information of the optical disc from the filtered signal. Essential information can be recorded in a recordable optical disc by phase change using an existing disc initializing apparatus after deposition of a recording layer and before initialization of the optical disc. Therefore, an additional recording apparatus and process is not necessary, and no damage caused by a high energy of laser occurs in the optical disc.