Control Strategies Towards Faster Quantitative Imaging in Atomic Force Microscopy

Atomic force microscopes provide unprecedented access to surfaces at the nanometer level both for imaging and for local surface modifications. Precise positioning, accurate control of interaction forces and speed are critical issues when operating these instruments. This paper summarizes how modern model-based control strategies lead to higher permissible imaging speeds, improved control over the interaction forces and better tracking of surface features compared with conventional proportional-integral-controlled atomic force microscopes. In particular, H∞- and l1-optimal methods are applied to control both lateral scanning motions and vertical positioning. Various experimental results verify the achieved performance.