Experimental visualization of air bearing mode shapes

Air bearing vibrations at nanometer clearance levels are a limiting factor for reduction of head-media spacing. This paper presents a method for measuring both natural frequency and mode shape of the entire head gimbal assembly at frequencies typically associated with air bearing vibration. An acoustic emission sensor is used to provide a reference signal to a scanning laser Doppler vibrometer system. The good correlation between the acoustic signal and structural motion enables mode shapes to be constructed and animated. The motion of the gimbal and load beam during contact-induced air bearing vibration is found to be significant. We use this experimental method to show differences in system response depending on the air bearing design for thermally actuated heads.