REPLAY METHOD AND REPLAY DEVICE

摘要

A recording medium having formed therein track groups having a plurality of adjacent information recording tracks formed using a shorter track pitch (Tp1) than a track pitch corresponding to an optical cutoff specified by the wavelength of an irradiated laser light and the NA of a radiating optical system. A track group pitch (TpG) of the track groups is longer than the track pitch corresponding to the optical cutoff. Difference signals for each radial contrast signal obtained by each reflected-light information for two replay laser spots radiated on the track groups are used as tracking error signals. At least one replay laser spot is made to be on-track on one of the information recording tracks and data is replayed from the reflected light information thereof, by tracking servo control using these tracking error signals.