Control of vertical axis of a video-speed AFM nanopositioner

This paper presents the combination of active and passive damping control techniques to increase the vertical tracking bandwidth of a fast nanopositioner for video-speed atomic force microscopy (AFM). The passive damping technique utilizes an inertial counterbalance arrangement to mechanically cancel the low 20-kHz vertical resonant mode of the nanopositioner; and the active control technique employs an integral resonant control technique to augment damping to resonant modes at 60 kHz and above. The combined damping techniques increases the vertical tracking bandwidth from 2.3 kHz to 28.1 kHz. This allow high-quality AFM images to be recorded at video speed, i.e. up to 1000 Hz line rate without noticeable image artifacts.