| 摘要 |
PURPOSE:To well record and erase information in all areas from an inner peripheral part to a outer peripheral part by setting the layer thickness of a dielectric layer provided between a recording film and a reflective layer so that it is thicker in the outer peripheral part than the inner peripheral part. CONSTITUTION:The layer thickness of the dielectric layer is made thicker in the outer peripheral part than the inner peripheral part. A dielectric layer 2 which consists of an SiO2 and has about 150nm thickness, a recording film 3 which consists of materials where 5% Ge and 10% Sn are added to a TeOx (x 1.1) and has about 50nm thickness, a dielectric layer 4 consisting of an SiO2, and a reflective layer 5 which consists of an Al thin film and has about 50nm thickness are formed on a polycarbonate disk-shaped transparent substrate 1 having a guide groove 8, and a protective substrate 7 is provided on the reflective layer 5 with an adhesive between them. The layer thickness of the dielectric layer 4 is so continuously changed that it is thinner in the inner peripheral part and is thicker in the outer peripheral part and this thickness is about 80nm in the position of 60mm diameter and is about 150nm in the position of 110mm diameter. |
