The noise of coated cantilevers

Abstract

In atomic force microscopy, cantilevers with a reflective coating are often used to reduce optical shot noise for deflection detection. However, static AFM experiments can be limited by classical noise and therefore may not benefit from a reduction in shot noise. Furthermore, the cantilever coating has the detrimental side-effect of coupling light power fluctuations into true cantilever bending caused by time-varying thermal stresses. Here, we distinguish three classes of noise: detection, force, and displacement noise. We discuss these noises with respect to cantilever coating in the context of both static and dynamic AFM experiments. Finally, we present a patterned cantilever coating which reduces the impact of these noises.