A fast scanning strategy based on trajectory shaping for atomic force microscopy

To improve the scanning speed of an atomic force microscopy (AFM), a smooth scanning pattern is elaborately devised via trajectory shaping in this paper, so as to achieve fast imaging without hardware modification. Specifically, in the proposed scanning method, the piezoelectric actuator tracks a well-designed smooth periodic signal in x-direction, and simultaneously tracks a step signal in y-direction. The advantage of the proposed method is that it does not require additional data reprocessing to construct the morphology of the sample surface, while significantly increasing the scanning bandwidth restricted by the raster scanning method. Particularly, to directly utilize the height data collected by scanning to produce the sample morphology, the forward process in the common raster scanning mode is retained in the proposed method, the tracking signal in the forward process is thus set to a ramp function in x-direction. In addition, to ensure the continuity and smoothness of the entire tracking signal in x-direction, a segment of a sine curve is uniquely determined as the backward tracking signal by position and acceleration constraints, so as to ensure that the forward and backward curves are continuous and acceleration-continuous at the intersection point. Moreover, the frequency spectrum analysis of the designed smooth signal is carried out to exhibit the depressed amplitudes of high-frequency components, which demonstrates that the proposed method is able to reduce the resonance in AFM high-speed scanning, so as to improve the capacity of rapidly generating high-quality images. Finally, convincing comparison experiments are implemented to verify the imaging performance of the designed scanning algorithm.