Independent measurement of air-bearing pitch, roll, and vertical modulation

We describe a method of measuring the dynamic changes in pitch and roll angle of air-bearing sliders used in hard disk drive magnetic recording. The technique provides simultaneous, single-point measurements of the dynamic changes in pitch angle, roll angle, and vertical position. We apply the technique to characterize the dynamic responses of a slider reacting to an idealized disk defect and demonstrate how different translation and rotational modes get excited sequentially. Spectrogram analysis is then applied to illustrate the changes in frequency content of the three different modulation modes. We model the slider response as an impulse response to provide experimental determination of response frequencies and damping factors. We perform these analyses as a function of rotational velocity and find that response frequencies increase and damping factors decrease with decreasing velocity. These analyses provide insight into factors controlling slider dynamics and demonstrate the utility of the technique.