Patent ID: 7414940

Claim:
An optical disk drive, comprising: an optical pick-up unit; an analog-to-digital converter coupled to receive signals from detectors in the optical pick-up unit and to convert the received signals into digital signals; a digital signal processor coupled to receive the digital signals such that the digital signal processor receives digitized versions of each of the signals from the detectors, the digital signal processor calculating a focus error signal and a tracking error signal from the digital signals; and a driver coupled to control a focus position of the optical pick-up unit wherein the digital signal processor executes an algorithm that determines a gain factor to be applied to the focus error signal, the algorithm including the acts of: commanding the driver to vary the focus position of the optical pick-up unit; determining a peak for a focus sum signal for the varied focus positions; calculating a sum threshold from the peak and a corresponding focus position that provides a focus sum signal corresponding to the sum threshold; commanding the driver to sinusoidally vary the focus position about the corresponding focus position; and processing the focus error signal calculated by the digital signal processor from the sinusoidally varied focus positions to determine the gain factor.