Patent ID: 8345521

Claim:
An optical disc apparatus comprising: a light separator configured to separate a light beam emitted from a light source into a main beam and a sub-beam; an objective lens configured to, when the light beam is condensed and irradiated to an optical disc having a uniform recording layer in which a track is formed by record marks, irradiate at least part of the sub-beam to an area where the main beam is not irradiated in a radial direction which is defined as a direction of radius of the optical disc; and a signal generating unit configured to generate a mark layer distance signal, representing a distance between a focus of the light beam and a mark layer to which the track belongs, based on a return light beam resulting from at least one of the main beam and the sub-beam, which has been irradiated to the track; wherein the mark layer distance signal is a corrected pull-in signal having a signal level that increases as the distance between the focus of the light beam and the mark layer decreases.