A servo system that calibrates a cross-talk gain parameter in a tracking error
signal to focus error signal crosstalk correction is provided. The cross-talk gain
parameter can be optimized such that the effects of a perturbation applied to the
tracking servo loop on an adjusted focus error signal, i.e. a focus error signal
that has been corrected for crosstalk, is minimized. The optimized cross-talk gain,
then, can be set to the cross-talk gain of a set of cross-talk gains that results
in the lowest value of a frequency component of the adjusted focus error signal
while a perturbation at the frequency is being applied to the tracking servo loop.