A method and apparatus for calibrating a glide head and
detector system performs a pre-screening to ensure the quality of the glide head and the
piezoelectric sensor in the detection
system. The glide head and the
piezoelectric sensor detect a
signal when the glide head makes contact with the disk, such as a magnetic recording disk. Calibration of the detection
system utilizes a specially made bump disk that has asperities of desired height and size that protrude out of a flat disk surface. The glide head is flown over the bump disk, and by gradually reducing the disk
spinning velocity, the head is brought closer to the disk and eventually into contact with the asperity. The onset of contact, as detected by the
piezoelectric sensor, defines a disk
spinning velocity for the head to fly at the desired height. In order to decouple the glide head flying characteristics and the piezoelectric quality and
transfer function from other factors that affect the calibration of the detection system,
laser pulses are directed at the glide head. Head vibrations are introduced in the glide head and detected by the piezoelectric sensor. The head excitations are recorded as a
spectrogram in which the
resonance frequencies are observed. From the amplitude and frequency readings, head
resonance frequencies are identified and the piezoelectric sensor response is characterized. This allows the pre-screening of the head /
sensor system and the decoupling of the glide head flying characteristics and the piezoelectric sensor quality from the asperity integrity effects on the calibration of the detection system.