| 摘要 |
PURPOSE:To eliminate the unbalance of absorbance by specifying the reflectivity of unrecorded parts to two wavelengths lambda1, lambda2 and the reflectivity of the recording marks formed by irradiation with a laser beam. CONSTITUTION:The structure to satisfy the following optical characteristics (lambda1<lambda2) for the two wavelengths lambda1, lambda2, is determined: The structure has the reflectivity 20%<= R10 <=50%, 15%<=(R10-R11)<=30%, 58% R2o, 40%<=(R20-R21), where R10 is the reflectivity of the unrecorded part to the wavelength lambda10; R11 is the reflectivity to the wavelength lambda1 of the recording marks formed by the irradiation with the laser beam. Protective layers 2, 9, a recording layer 3, a protective layer 4 and a reflection layer 5 are successively formed on a substrate and further, the same PC disk is stuck as the protective substrate 7 by an adhesive 6 thereto. The optical constants of the respective layers are measured. The reflectivity over the entire part of the recording medium is calculated when the film thicknesses are changed from such data, by which the optimum film thickness constitution is determined. The absorbance of light is determined from the energy balance of light at the respective boundaries, by which the variations are eliminated. |
