Patent ID: 7688702

Claim:
A single-sided dual-layer optical disc comprising: an optically transparent layer; a first recording layer accessed by a red laser beam having a center wave length of 650 nm; an intermediate layer; and a second recording layer accessed by a blue-violet laser beam having a center wave length of 405 nm, wherein the optically transparent layer, the first recording layer, the intermediate layer, and the second recording layer are sequentially disposed in a laser beam incidence direction, wherein a thickness of the optically transparent layer, which is a distance from a light incident surface to the first recording layer, is 550 to 575 μm, wherein a thickness of the intermediate layer, which is a distance between the first and second recording layers, is 29 to 47 μm, wherein a surface recording density of the second recording layer is at least 3 times that of the first recording layer, wherein a reflectivity of the first recording layer with respect to the red laser beam incident on the optical disc is greater than or equal to 45%, and wherein a reflectivity of the second recording layer with respect to the blue-violet laser beam incident on the optical disc is greater than or equal to 8%, wherein the reflectivity of the first recording layer with respect to the red laser beam is larger than the reflectivity of the second recording layer with respect to the blue-violet laser beam, and wherein a transmittance of the first recording layer with respect to the blue-violet laser beam is larger than a transmittance of the first recording layer with respect to the red laser beam.