| 摘要 |
PROBLEM TO BE SOLVED: To reproduce and/or record an optical recording medium having the different thickness of an optically transparent layer in the non-aberration state. SOLUTION: A laser beam from a light source of a laser diode 11 is supplied to a condenser lens 14 through a beam splitter 13 and an aberration compensating mechanism 16. The condenser lens 14 forms a minute spot on the recording surface of an optical recording medium. Optical disks 21A, 21B having thicknesses of optically transparent layers 22A, 22B different from each other, e.g. 1.2mm and 0.6mm are used when information recorded in the optical disk 21 is read out, an aberration compensating lens 17a of the aberration compensating mechanism 16 is changed over/selected and the spherical aberration due to the optically transparent layer 22A is compensated. When information recorded in the optical disk 21B is read out, an aberration compensating lens 17b of the aberration compensating mechanism 16 is changed over/selected. |
