Resonant controller for fast atomic force microscopy

The imaging performance of the atomic force microscope (AFM) in higher scanning speed is limited to the one percent of the first resonant frequency of it´s scanning unit i.e., piezoelectric tube scanner (PTS). In order to speed up the functioning of the AFM for high speed imaging, a resonant controller with an integral action has been applied in the both x and y axis of the PTS for damping the resonant mode of the scanner and improve the tracking performance. The overall closed-loop system with this scheme has higher bandwidth with improved gain and phase margin than the existing PI controller. It can reduce the cross coupling of the scanner and allows faster scanning. To measure the performance improvement of the proposed scheme a comparison has been made between the proposed controller scanned image and the existing AFM PI controller scanned image.