| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent recording and reproducing characteristics with a high reflectivity and high modulation degree by providing the surface of a transparent disk-like substrate formed with pregrooves of a track pitch in a specific range with a recording layer which contains dyestuffs capable of recording information by irradiation with a laser beam and is specified in the relation of the complex refractive index of the recording layer to the wavelengths of the laser beams for recording and reproducing and the thickness of the recording layer to a specific range. SOLUTION: The surface of the transparent disk-like substrate formed with the pregrooves of 0.6 to 0.9 μm in the track pitch is provided with the recording layer contg. the dyestuffs capable of recording the information by irradiation with the laser beam and a reflection layer. The recording layer is so formed as to attain 0.53<nRd/λR<0.77, 0.005<kW, kR<0.35 with respect to the wavelengths λW, λR (nm) of the laser beams for recording and reproducing, where nR and kR denote the absolute values of the real number part and virtual number part of the complex refractive index of the recording layer with respect to the wavelength λR of the laser beam for reproducing; kW denotes the absolute value of the virtual number of the recording layer with respect to the wavelength λW of the laser beam for recording and d denotes the thickness of the recording layer. |
