OPTICAL DISK DRIVE WITH SPHERICAL ABERRATION MEASUREMENT AND METHOD OF MEASURING SPHERICAL ABERRATION IN AN OPTICAL DISK DRIVE

摘要

The invention relates to an optical disk drive. The optical disk drive has an objective lens to be driven by a focus actuator with a focus offset for focusing an incident beam onto an optical disk into a spot with a spherical aberration, and a processor to derive a first and a second characteristic from a sensor output signal and obtain a spherical aberration correction value (SA) from a pre-determined function, the pre-determined function defining a spherical aberration correction value in dependence on a focus offset difference value (DeltaFO). The focus offset difference value (DeltaFO) is determined from a difference between a second optimal focus offset at which the second characteristic is optimal and a first optimal focus offset at which the first characteristic is optimal. The spherical aberration correction value (SA) can be used to achieve a correction to the spherical aberration of the spot.