| 摘要 |
PROBLEM TO BE SOLVED: To enhance the sensitivity to recording light to realize a high speed recording, by setting each of imaginary part of a complex refractive index of a film of a light absorbing layer, average film thickness of the light absorbing layer, and a resultant light absorbing coefficient in appropriate ranges. SOLUTION: The light absorbing coefficient A (Abs) of a light absorbing layer 3 satisfies 0.13<=A<=0.21. In addition, imaginary part k of a complex refractive index of a film of the light absorbing layer 3 at a wavelength of a recording light L1 and an average film thickness dav of the light absorbing layer 3 satisfy 6.0<=k.dav<=12.0. The average film thickness dav of the light absorbing layer 3 satisfies 40 mm<=dav<=85 mm. A certain material can be added to the light absorbing layer 3 so that the imaginary part k of the complex refractive index of the film of the light absorbing layer 3 at the wavelength of the recording light L1 can satisfy 0.1<=k<=2.0. The above-mentioned light absorbing material can contain therein a benzo-type cyanine pigment of 80 Mol% or more. A recording sensitivity deteriorates when A<0.13 or k.dav<6, and a jitter deteriorates when A>0.21 or k.dav>12. |
