| 摘要 |
PURPOSE:To enable complete recording and erasing by using a recording medium whose optical constant is decreased by heating and rapid cooling and increased by heating and slow cooling. CONSTITUTION:A recording medium whose optical constant is changed before and after recording is used. The optical constant is decreased by heating and rapid cooling, resulting in a decrease in the reflectance and an increase in the transmittance, and it is increased by heating and slow cooling, resulting in an increase in the reflectance and a decrease in the transmittance. For example, a thin chalcogenide glass film or a TeOx-base thin film is formed on a substrate such as a glass or plastic sheet by vapor deposition, sputtering or other method to obtain the recording medium. When information is recorded, light is irradiated with high power to melt the irradiated part, and the part is rapidly cooled. When the recorded information is erased, light is irradiated with high power to melt the irradiated part, the power is reduced at once, and the part is slowly cooled while irradiating light with low power.
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