Experimental Investigation of the Bernoulli Head/Disk Interface

The Bernoulli head/disk interface is investigated using interferometry as well as the measurement of acoustic emission, normal force, and disk deflection. The dependence of head-to-disk spacing on radial head position and velocity for upper and lower heads is measured by monochromatic light interferometry. Acoustic emission measurements are used to study intermittent contacts between head and flexible disk. The normal force between the head and the disk h measured and is found to correlate with the acoustic emission signal. The disk deflection characteristics show that the normal force at the head/disk interface is related to the vertical displacement of the head. The normal force at the head/disk interface is determined from the relative disk deflection using the disk stiffness in the normal direction and compared with the measured force.