| 摘要 |
PURPOSE:To allow the recording of information at a high degree of many values by setting the product of the thickness and refractive index of a medium layer approximately at integer times the half wavelength of the wavelength to generate multiple interferences by the luminous flux with which the medium layer is irradiated. CONSTITUTION:Reflecting layers 12a, 12b, 14a, 14b consisting of multiple layers are formed by alternately stacking layers having the high refractive index and layers having the low refractive index at a specified optical path length thickness. Dielectrics, such as SiO2, Si3N4, MgF4, and Al2O3, are used as the material of the respective reflecting layers. The product of the thickness of the medium layer and the refractive index of the medium layer is about integer times the half wavelength of the wavelength to generate the multiple interferences with the luminous flux with which the medium layer is irradiated. The high SNR and the high degree of the many values are obtd. and the efficient reproduction is executed. |
