Comparison of flying height measurement between multi-channel laser interferometer and the capacitance probe slider

The authors studied the dynamics of a capacitance probe slider by measuring the head-disk spacing during CSS (contact-start-stop) cycles and during steady-state flying. They measured the head-disk spacing with both the MCLI and the capacitance probe slider simultaneously and then attempted to correlate the spacing fluctuation results. They first determined the calibration factor by measuring the flying height and the change in the capacitance during the CSS cycle. As expected, it was observed that the change in the capacitance is a nonlinear function of the change in the spacing. However, it was also discovered that the same calibration factor determined by a CSS cycle cannot be applied to calibrate the spacing fluctuation measurements made during steady-state flying conditions. The disagreement is due to spacing averaging caused by the finite size of the capacitance pad