Self-oscillation mode induced in an atomic force microscope cantilever

Abstract

We developed a technique to excite the self-oscillation of a commercially available metal-coated cantilever and detect the deflection simultaneously with only a single optical fiber. The technique is based on the fact that the light transmitted to a cantilever in the fiber-optic interferometer induces the photothermal positive feedback to the cantilever oscillation. The model analysis on the cantilever oscillation shows that the product of the slope of an intensity curve and the thermal coefficient of deflection of the cantilever should be greater than the product of the damping parameter and the dynamic heat capacity to excite the self-oscillation, which was confirmed by experiment. It can be used either to excite the self-oscillation in the frequency modulation atomic force microscopy or to avoid it in normal force microscopy. (C) 2002 American Institute of Physics.