Measurement and nonlinear correction for micro-displacement of piezoceramic tube

A simple way to measure and correct the micro-displacement of a piezoceramic tube used in an Atom Force Microscope (AFM) is proposed. The X/Y micro-displacement is detected by an eddy current meter and it is amplified by 100 times to improve the detection sensitivity. The relationships between the displacements of piezocaramic tube and the control voltages are obtained, and the highest resolution of displacement is calculated to be 0.4 nm. According to the working feature of the tube, the nonlinear correction is realized by applying non-equidistant control voltage sequences to scanning equidistant pixel, in which non-equidistant control voltage sequences with different pixel resolutions are obtained through interpolation based on the measured displacement-voltage relationship. The experimental results show that the maximum hysteresis error of full scale is reduced from 10.1% to 0.4%. It is concluded that the proposed method can adjust the scan frequency and pixel resolution easily, and can reduce the complexity of correction algorithm greatly.