Patent ID: 7995439

Claim:
An optical disc apparatus comprising: a reproducing light source that emits a reproducing light beam not to be converged to a single spot at a time of convergence onto an optical disc having a recording layer including one or more mark layers where a plurality of recording marks representing respective pieces of information are arranged on a virtual plane and a reflection surface for reflecting the reproducing light beam to be used for reproducing the pieces of information; an objective lens that changes an angle of divergence of the reproducing light beam into substantially collimated light from an irradiation surface side opposite to the reflection surface with the recording layer interposed between them in the optical disc and projects collimated light so as to include a target position in a target mark layer; a reproducing light detecting section that has a detection region at a confocal point with the target position of the reproducing light beam passing through the recording layer, reflected by the reflection surface and passing through the recording layer and the objective lens once again to detect a quantity of light in the detection region; and a reproduction processing section that recognizes the presence or absence of a recording mark at the target position according to an outcome of detection in the detection region in order to reproduce a corresponding piece of information.