A moving window correlation method to reduce the distortion of SPM images
Wei Chu, Joseph Fu, Ronald G. Dixson, Ndubuisi G. Orji, Theodore V. Vorburger
Many scanning probe microscopes (SPMs), such as the scanning tunneling microscope (STM) and atomic force microscope (AFM), use piezoelectric actuators operating in open loop for generating the scans of the surfaces. However, nonlinearities mainly caused by hysteresis and drift of piezoelectric actuators reduce the positioning accuracy and produce distorted images. A moving window correlation method is proposed in this paper to determine and quantify the hysteresis. This method requires both trace and retrace profiles to be recorded. With a window imposed on each of the profiles, correlations are implemented between the data inside two windows to find corresponding pixel pairs on two different profiles but the same physical positions along the fast scanning axis (x). The x-distances between pixel pairs are calculated and then a simple correction scheme is applied to reduce the distortion.