Abstract: An optimizing of a gain in a servo control loop (21) of an optical drive is performed for the control of an actuator for focusing and tracking a laser beam (10) for reading or writing data from/to optical discs (1), wherein the actuator is controlled by a servo controller (20) in the control loop (21), by means of an algorithm performing the steps: predetermining a reference oscillation level for the servo control loop (21), iteratively checking if a power output from the control loop (21) used as an dissipation level value is less than the reference oscillation level, increasing the gain in the servo control loop in each iteration step until said dissipation level value is equal to or greater than the reference oscillation level and then decreasing the gain in the control loop by a margin value.

Abstract: A method and apparatus for a feedback loop (30) used with a servo controller (14) to control an actuator (13, 17) of an optical disc drive. The gain (18) in the feedback loop (30) determines the bandwidth of the actuator (13, 17) in accordance with predetermined parameters for predetermined intervals. High rotational disk speeds, especially during writing, necessitate that the actuator servo controller feedback loop have a high loop gain and can become critical. Higher gains will cause oscillations in the loop. Loop gain spread from sources such as detector sensitivity differences on recorded and non recorded areas, is controlled by setting the control gain at an initial value lower than the maximal value in order to avoid oscillations. The control gain is then adjusted to a maximum value by means of an AGC mechanism. This AGC mechanism is activated for short periods of times to adjust the gain.