PROJECT TITLE :

Real-Time Reconstruction of Multimode Tip Motion of Microcantilevers in Dynamic Atomic Force Microscopy

ABSTRACT:

A modal projection filtering method is proposed for the dynamic atomic force microscopy (AFM) to accurately reconstruct the multimode tip motion of the AFM microcantilever from the single measurement signal of the optical lever methodology in real time. The optical lever technique is inherently a slope detection methodology, wherein each individual dynamic mode pertinent to the slope detection principle of the measurement system has its own distinct measurement sensitivity as a result of of the distinctive dynamic mode form per a mode. The proposed modal projection filtering technique uses the experimentally identified multimode dynamic model of the AFM microcantilever together with the calibrated measurement sensitivities of individual dynamic modes to style the modal projection filters to extract the responses of individual dynamic modes from the one measurement signal. The tip motion of the AFM microcantilever is then accurately reconstructed by using a linear superposition of the extracted responses of multiple dynamic modes. The designed modal projection filters were implemented in a very field programmable gate array for real-time computation with an update rate of 1 MHz. Laptop simulations and experimental investigations were performed to validate the principle of and to demonstrate the performance of the proposed method.