Estimator based multi-eigenmode control of cantilevers in multifrequency Atomic Force Microscopy

Today, multifrequency Atomic Force Microscopy is a popular technique to extract properties of a sample surface other than the topography through different channels. Such channels are represented by the higher eigenmodes and harmonics of the flexural vibrations of the cantilever. In one method two or more eigenmodes are actuated simultaneously, whereas another method captures the harmonics excited from the first eigenmode tapping the surface. In this paper, we present a compensation strategy to modify the dynamics of two transverse eigenmodes independently. The modeling, compensator design, implementation and imaging performance on a polymer sample is outlined. In particular low Q factors in the first and high Q factors in the second eigenmode indicate a strong improvement in material contrast mapping. As the imaging bandwidth depends on the Q factor of the first eigenmode, the imaging rate is increased simultaneously.