Identification and open-loop tracking control of a piezoelectric tube scanner for high-speed scanning-probe microscopy

Fast and precise positioning is a basic requirement for nanotechnology applications. Many scanning-probe microscopes (SPM) use a piezoelectric tube scanner for actuation with nanometer resolution in all three spatial directions. Due to the dynamics of the actuator, the imaging speed of the SPM is limited. By applying model-based open-loop control, the dynamic behavior of the scanner can be compensated, reducing the displacement error, topographical artifacts, modulation of the interaction force, and modulation of the relative tip-sample velocity. The open-loop controlled system enables imaging of up to 125-μm-sized samples at a line scan rate of 122 Hz, which is about 15 times faster than the commercial system.