Patent ID: 7389520

Claim:
An optical disc with a center hole, the optical disc comprising: a signal substrate; a signal recording layer for storing data; a transparent protective layer having a 10 μm to 200 μm thickness disposed over said signal recording layer; and a protrusion projecting from a surface of said transparent protective layer, wherein a signal area of the optical disc is located over said signal recording layer, a clamping area of the optical disc is located between the signal area and the center hole, and said protrusion is disposed at an area of the optical disc between the center hole and the clamping area, wherein the data is recorded to and/or read from the signal recording layer using an optical head with a 0.7 to 0.9 numeric aperture, and a wavelength of light for recording and/or reading the data in said signal recording layer is 410 nm or less.