Optical disk, aberration correction method and optical disk apparatus

摘要

The invention provides an optical disk wherein a spherical aberration caused by a displacement of the thickness of a transparent substrate of the optical disk can be corrected without giving rise to an increase in scale of the apparatus or an increase of the cost. The recording face of an information recording layer of the optical disk on which a very small spot for recording or playing back information is formed is covered with the transparent substrate. A particular region is provided at a portion of a lead-in region formed in a disk innermost circumference region of the recording face of the information recording layer, and a particular pattern with which a spherical aberration of a very small spot appearing in accordance with a displacement of the thickness of the transparent substrate from a prescribed value is formed in the particular region.