An investigation of the ''take-off'' characteristic of tri-pad sliders using phase demodulated laser interferometry

The interaction between a tri-pad slider and a rigid disk during ''take-off'' is characterized using phase demodulated laser interferometry and acoustic emission (AE). A double peak was observed in the AE signal during the ''take-off''. A biquadratic surface fit for the air bearing surface was used and it was found that the transition between the first peak and the second peak corresponds to a change in contact location from the rails to the tri-pad of the slider. The second peak is shown to correspond to a change in contact location from the leading to the trailing edge of the third pad. As the disk linear velocity increases, the tri-pad slider increases its pitch angle, but remains in contact with the disk, pivoting on the trailing edge of the tri-pad.