The resonant behavior of segmented piezoceramic tubes

Segmented piezoceramic tubes are widely used as the scanning actuators in scanning probe microscopes. A good understanding of the tube behavior is necessary in order to implement the electronic feedback control that is required for image scanning. Previous studies of the tubes have given contradictory results for the phase change between the driving signal and mechanical displacement at the lowest resonance frequency. In addition, the commonplace method of measurement of resonance frequency by piezoelectric self-excitation occasionally gives anomalous results. In this paper, new measurements are described, which explain some of these anomalies. The measurements of off-axis resonant response are reported. The resonant behavior is shown to depend on the mounting of the tube base, as well as the tube itself. A potential pitfall in the common method of resonance measurement by self-excitation is shown to exist.