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S. Ito, M. Poik, J. Schlarp, G. Schitter:
"Atomic Force Microscopy Breaking Through the Vertical Range-Bandwidth Tradeoff";
IEEE Transactions on Industrial Electronics, (2020), 9 pages.

This paper proposes a mechatronic system design for atomic force microscopes (AFMs) in order to realize a large range and high control bandwidth of the vertical probe motion by a flexure-guided voice coil actuator. The first mechanical resonant frequency of the actuator is decreased to 67Hz for a large motion while the second resonant frequency is maximized to 1.15kHz. The frequency band between the resonances enables two-degree-of-freedom control with a position sensor to realize a control bandwidth of 881Hz, which is 13 times higher than the first resonance that is the limitation of conventional AFMs. The closed-loop actuator achieves a positioning resolution of 1.7nm and a nonlinearity of 0.02% for a motion range of 700μm. Consequently, the actuator realizes a range-bandwidth product of 617kHzμm, breaking through a theoretical limit of piezoelectric actuators (567kHzμm). The high performance of the actuator is further confirmed by 400μm topography measurement in the constant force mode with a bandwidth of 197Hz. The achieved resolution of the topography measurement is 2.9nm, and it is demonstrated by successfully imaging nanostructures on a CD-ROM disk.

Atomic force microscopy , Mechatronics , Nanopositioning , Precision engineering , Design for control

http://dx.doi.org/10.1109/TIE.2020.2982113

https://publik.tuwien.ac.at/files/publik_288567.pdf