PURPOSE: To increase a transfer speed by correcting a position shift between a spot and each of tracks of an optical disk due to a difference in curvature between the inner and outer peripheries of the track or the eccentricity of a disk, and recording, reproducing, or erasing information in parallel.
CONSTITUTION: Variable wavelength lasers 1a - 1c are used and the wavelength of laser light is varied at a high speed by spots 11a - 11c by using the frequency dependency of the diffracted light projection angle of an optical system for position shifts between the spots 11a - 11c and the track due to the difference in curvature between the inner and outer peripheries of the track or the eccentricity of the disk 13, thereby moving the light spots 11a - 11c at right angles to the track within fine ranges. While the disk is irradiated with the light spots 11a - 11c of information input and output linearly and slantingly almost in parallel to the track, tracking and focusing control is performed at the same time to record, reproduce, or erase the information on adjacent tracks in parallel. Consequently, the transfer speed of the information is increased.
SHIBA MASATAKA
YOSHIDA MINORU
