Patent ID: 7570548

Claim:
An optical pickup comprising: a laser light source; a spherical aberration compensation unit that adds a spherical aberration of a variable amount to a laser beam emitted from said laser light source; an objective lens that focuses the laser beam to which said spherical aberration has been added, onto an optical disk; an optical detector that receives the laser beam reflected on the optical disk; a signal processing unit that generates a readout signal, tracking error signal and focus error signal from the output of said optical detector; an actuator that drives said objective lens based on said focus error signal and said tracking error signal; and a nonvolatile memory from which data can be electronically read out; wherein the focus error signal is almost zero when the readout signal jitter reaches a minimum; and wherein data concerning a difference between the spherical aberration when the readout signal jitter reaches a minimum and the spherical aberration when the tracking error signal amplitude reaches a maximum is recorded in said nonvolatile memory.