| 摘要 |
PROBLEM TO BE SOLVED: To enable adequate recording and reproducing of information with light beams from a long wavelength to a short wavelength by forming a phase transition type recording layer which is disposed on a substrate having guide grooves for light beam tracking and is changed in its optical characteristics by the phase transition caused by irradiation with the light beams in such a manner that the film thickness thereof satisfies a specific relation with the wavelengths of the light beams. SOLUTION: The film thickness Y of the recording layer 1 on the protective layer 3 of the optical disk substrate 6 is specified to a range of Y value ±5% (X, Y are nm) by specifying the relational expression to Y=0.064X-17 when the wavelength X of the light beam is 400 to 700 nm. When the wavelength X of the light beam is 270 to 400 nm or >=700 nm, the film thickness Y of the recording layer 1 is set larger or smaller than the range of Y value ±5% of the relational expression. The recording layer 1 is formed by using a GeSbTe based chalcogenide amorphous semiconductor material of which the state is changed when subjected to irradiation with the light beam and disposing the protective layer 2, a reflection layer 4 and the protective layer 5 thereon. As a result, the adequate dealing with the wavelength of the light beam for recording and reproducing is made possible. |
