Direct tip-sample interaction force control for the dynamic mode atomic force microscopy

A control method, in which the tip-sample interaction force of each tapping cycle is directly regulated, is proposed for dynamic mode atomic force microscopy. It does not rely on the steady-state relationship between the cantilever's oscillation amplitude and tip-to-sample distance, and therefore the cantilever's transient dynamics and the time delay of rms-dc converter are irrelevant. Experimental results clearly demonstrate that the proposed method regulates the tip-sample interaction force for each tapping cycle and time delay effect is eliminated. Computer simulations also show that the proposed method reconstructs a step change in topography within two tapping cycles, independent of the cantilever's transient dynamics.