Quantitative Measurements of Electromechanical Response with a Metrological Atomic Force Microscope

TL;DR

This paper introduces a metrological AFM combining optical beam deflection and laser Doppler vibrometry to enable precise, quantitative measurements of cantilever displacement and velocity, improving electromechanical characterization.

Contribution

It presents a novel AFM setup that integrates OBD with LDV for accurate, direct measurements of cantilever motion, advancing quantitative electromechanical analysis.

Findings

Successful measurement of cantilever velocity and displacement.

Quantitative assessment of piezoelectric sensitivity.

Enhanced accuracy in electromechanical experiments.

Abstract

An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance and tends to be mechanically robust. However, it represents an 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, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy (PFM). As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity, a longstanding goal in the electromechanical community.