Patent ID: 7365932

Claim:
A disk drive comprising: (a) a disk having a plurality of servo sectors comprising servo information, the servo sectors defining a plurality of servo tracks; (b) an actuator arm; (c) a head attached to a distal end of the actuator arm; (d) a voice coil motor for rotating the actuator arm about a pivot; (e) an optical sensor that generates a first position signal representing a position of the actuator arm with respect to the disk, wherein the first position signal is substantially unaffected by a vibration mode of the actuator arm; and (f) control circuitry that: processes the servo information to generate a second position signal representing a position of the head with respect to the disk, wherein the second position signal comprises a significant component due to the vibration mode of the actuator arm; substantially rejects the significant component due to the vibration mode of the actuator arm in response to the first and second position signals; and generates a control signal applied to the voice coil motor in response to the first and second position signals.