OPTICAL DISC AND OPTICAL DISC REPRODUCTION DEVICE

摘要

An optical disc and an optical disc reproducing device are provided to reproduce record marks in different sizes below a resolution limit by using a plane having discontinuous refractive indices, and to keep laser power for super-resolution reproduction constant regardless of the size of the record mark. An optical disc comprises a substrate(1) having a recording layer(3) for recording information on the substrate, and a material layer(5) with a viscosity variable by laser beam irradiation, depending on light intensity or temperature. The material layer has a specific area whose viscosity is relatively lower than other area by irradiating laser beam with intensity above a threshold light intensity, or increasing temperature of the specific area above a predetermined temperature. Optical constant is remarkably changed at the boundary between of the specific area and other area.