Abstract: An optical disc apparatus, which discriminates types of optical discs having different thicknesses of transparent layers by using the same wavelength of laser light, includes an aberration correction unit for correcting spherical aberration, an objective lens for condensing the laser beam onto a recording surface of an optical disc, an actuator for moving the objective lens with respect to the optical disc, a signal detection unit for delivering a focus error signal or a sum light signal, a control unit for controlling the aberration correction unit, the actuator and the signal detection unit.

Abstract: A disk device includes: an optical pick-up, operable to reproduce data recorded in a disk; a flaw detector, operable to output a flaw detecting signal when a flaw formed on the disk is detected; and a jump controller, operable to control a track jump of the optical pick-up including a first track jump and a second track jump subsequent to the first track jump. A timing of starting to control the track jump corresponding to a still reproduction mode is determined based on a rotational position of the disk. When the flaw detecting signal is outputted in a time period in which the jump controller controls the first track jump corresponding to the still reproduction mode, the jump controller sets a timing for stating the second track jump to a timing different from a timing for starting the first track jump.

Abstract: An optical disc apparatus for recording information on a rewritable optical disc having a power calibration area (PCA) moves an optical pickup for optimum recording power calibration (OPC) from an innermost end to outward of the PCA, and stores an address where RF signal is first detected. If the stored address coincides with an address at the innermost end of the PCA, or if a usable area between the two addresses is smaller than to enable one-time OPC, the apparatus obtains an optimum recording power by overwriting on a used area at or near the innermost end of the PCA, and performs DC erase using the obtained optimum recording power. This enables DC erase and restoration of the PCA back to a usable area even if the PCA has no usable area at its innermost end, and even if it is difficult to detect a usable area in the PCA.