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Evaluation of Thermal Tolerance in Initializing Thin Optical Discs

We simulated a temperature change in thin phase-change optical discs that have various substrate thicknesses in order to evaluate the thermal tolerance of a polycarbonate substrate during DC sheet beam initialization. We simulated the temperature change by applying a finite difference method to the partial differential equation for heat conduction. In discs with substrates on both sides, the difference between the sums of the given heat while the temperature of each substrate is more than or equal to glass transition temperature for a disc with a 100-µm-thick substrate on both sides and a disc with a 5-µm-thick substrate on one or both sides, was within 5%. The sum of the given heat to the substrate for a disc with a substrate on one side, was about 1.5 times larger than that for a disc with substrates on both sides. These results showed that the initialization margin needed to obtain a good-quality initialization state with no thermal damage to the substrate is smaller for a disc with a substrate on one side than for that with substrates on both sides.