| 摘要 |
PURPOSE:To obtain a medium having large reproduction output by providing a spacer layer having specified characteristic between a recording layer and a substrate at a thickness near which the incidence-reflection factor of the substrate, becomes minimum in the state where the recording layer is not formed. CONSTITUTION:Percentage modulation of the medium can be heightened by providing a spacer layer 30 between the substrate 10 and recording layer 20. A part of incident light 100 through the substrate 10 is reflected at the interface between the substrate 10 and spacer 30 and at the interface between the spacer 30 and air, and becomes reflected light 200. Magnitude of the reflected light depends on refractive index and thickness of the spacer layer 30. Accordingly, material and thickness of the spacer layer 30 is selected to make the reflected light small. That is, it is necessary that refractive index of the spacer layer 30 is smaller that refractive index of the substrate 1.59, and the thickness is made to such a thickness that minimizes the magnitude of the reflected light 200. |
