T. Walsh, A. Labuda, M. Kocun, R. Proksch
Keywords: atomic force microscopy, AFM, piezoresponse, PFM, electromechanics, nanomechanics, cantilever, metrology
Summary:An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion — the so-called “last axis”. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever; this method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an inherently indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed for a myriad of applications, including but not limited to, in-situ measurements of cantilever oscillation modes for piezoresponse force microscopy. Here, we demonstrate an application of how this instrument has been used for accurate and repeatable quantification of piezoelectric sensitivity — a longstanding goal within the electromechanical community.