Head-disc dynamics of low resonance laser textures-a spectrogram analysis

Spectrogram analysis provides a systematic way to study the head-disc interface dynamics and demonstrates how the frequency spectrum varies during the head take-off or landing. The regular pattern laser texture has strong input excitations, which includes not only the fundamental frequency of bump pitch density but also the higher order harmonics. When the excitation frequencies intercept the system resonance frequencies, such as the slider/sensor body natural frequencies, the sensor output is amplified, which causes a false reading in the glide testing and glide avalanche measurement. Spiral-line laser texture solves the problem of resonance by completely removing the source of excitation