Correction of Hysteresis in SPM Images by a Moving Window Correlation Method

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 applied to the AFM images 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, cross correlation are calculated between the data inside two windows to find corresponding pixel pairs on two different profiles but the same physical positions along the fast scanning direction. This method is applied to the image distorted by the hysteresis attempting to correct the distortion.