Optical Disk Drive and Program Therefor

An optical disk drive, comprising:

• an objective lens for applying a beam from a laser to an optical disk;
• an actuator for driving the objective lens to cause a focal point of the beam applied to the optical disk to move in a focus direction;
• an optical sensor for detecting the beam reflected from the optical disk and outputting the beam as a detection signal;
• a generation unit for driving the actuator to output a shift in the focal point of the beam from the detection signal output from the optical sensor as a focus error signal;
• and
• a servo controller that receives an input of the focus error signal from the generation unit, for driving the actuator to control a focusing position of the beam,
• the servo controller comprising:
• a compensation unit for generating a drive signal for the actuator based on the focus error signal;
• a noise detection unit that receives an input of the drive signal output from the compensation unit, for detecting a noise component by changing a limiter characteristic according to a frequency of the drive signal;
• and
• a correction unit for correcting the drive signal by subtracting the noise component detected by the noise detection unit from the drive signal output from the compensation unit.