Contact force detection on a minute aperture mounted optical contact slider using an acoustic emission sensor

Abstract

Advances in the digital network society require both higher density and higher transfer rates in all sorts of storage systems. Especially in optical recording, the trend toward higher density and larger capacity requires novel surface-recording technologies that can drastically diminish head-to-medium spacing, resulting in an improvement in spatial resolution and, finally, a higher recording density. To this end, we have already proposed a novel contact optical head slider that is able to almost cancel the suspension load by generating hydrodynamic pressure, thus realizing a lower net contact force. Evaluating the dynamic contact force is requisite in realizing its stable sliding operation and higher signal readout performance. In this study, a continuous acoustic emission (AE) signal was utilized to detect the dynamic contact force. AE signal modulation was compared with the applied out-of-plane acceleration on a medium generated by a spindle combined piezo-electric actuator. It was clarified that the detected AE modulation amplitude was approximately proportional to the applied acceleration, and that utilizing AE modulation will be a useful method for evaluating dynamic contact force.