Patent ID: 7580327

Claim:
An optical head operable to record or reproduce signals on a first optical recording medium including only one recording layer and on a second optical recording medium including a plurality of recording layers, the optical head comprising: a light source; and a spherical aberration correction device arranged between the optical recording medium and the light source; wherein the spherical aberration correction device corrects spherical aberration of a recording layer disposed at a first predetermined distance on the first optical recording medium and a second predetermined distance on the second optical recording medium, before recording or reproducing signals, the first predetermined distance being a distance from a light-incident surface of the first optical recording medium to the one recording layer included therein and the second predetermined distance being a distance from a light-incident surface of the second optical recording medium to one of the plurality of recording layers included therein, and the first predetermined distance and the second predetermined distance are the same distance, and wherein, after driving the spherical aberration correction device so as to correct spherical aberration of the recording layer included in the first optical recording medium or the second optical recording medium, focus control is performed.