Patent ID: 7652967

Claim:
A single-sided triple layer optical disc comprising: a light transmission layer; a first recording layer and a second recording layer which are accessed with a first laser beam; and a third recording layer which is accessed with a second laser beam, these layers being arranged in that order in a direction in which the laser beams enter, wherein the distance of the light transmission layer from a light incidence plane to the first recording layer is a minimum of 550 μm, the distance between the first recording layer and the third recording layer is a maximum of 72 μm, the distance between the second recording layer and the third recording layer is a minimum of 15 μm, the distance between the first recording layer and the second recording layer is about 31 to 40 μm, the reflectivities of the first recording layer and the second recording layer with respect to the first laser beam are 18% or more, the ratio between the reflectivities being about 1.15 or less, and the areal recording density of the third recording layer is three times or more as high as the areal recording density of the first recording layer and the second recording layer.