| 摘要 |
PROBLEM TO BE SOLVED: To perform excellent recording/reproducing for light of a prescribed wavelength by deciding so that an absolute value of a complex specific dielectric constant of a recording layer in a recording wavelength of recording light and a reproducing wavelength of reproducing light is satisfied with a specified range. SOLUTION: This medium is constituted so as to sequentially form a translucent reflection layer, the recording layer containing dyestuff absorbing the recording light, a middle layer and a reflection layer on a transparent substrate. The absolute value (r) of (ε) shown by the relation (ε=ε1 -iε2 ) when the number part of the complex specific dielectric constant (ε) of the recording layer in the recording wavelength of the recording light and the reproducing wavelength of the reproducing light is defined as ε1 and the imaginary number part is defined as ε2 is decided so as to be satisfied with r>=10. In such an arrangement, a reflectance when the light of the recording wavelength or below of the recording light, e.g. the reproducing light is made incident from the substrate side is made so as to become 20% or above. Further, the complex specific dielectric constant (ε) of the recording layer is found by using the prescribed relation from the refractive index, the exhaustion coefficient of the recording layer, and the refractive index, and the exhaustion coefficient of the recording layer are decided from the film thickness dependency of the reflectance and the transmissivity for the recording layer formed on a quartz substrate. |
