Field Programmable Analog Array (FPAA) based control of an Atomic Force Microscope

For topography measurements and faster imaging with the AFM a high control-bandwidth is required. This paper presents an analog implementation of a model-based controller for a high-speed Atomic Force Microscope (AFM) using a new type of control hardware. The vertical positioning axis of the AFM scanner is modeled, and the imaging bandwidth is improved by means of model-based control. The new feedback controller, which is designed in the H_infin -framework, is implemented on a Field Programmable Analog Array (FPAA), which enables operation of the model-based controlled AFM system at a feedback bandwidth on the order of 100 kHz. Measured results demonstrate that the closed-loop system recovers from a step-like disturbance within 7 microseconds. Recorded AFM images verify a significant performance improvement of the model-based controlled system over the analog proportional-integral (PI) controlled AFM.