Feedforward compensation of piezo nonlinearity for high-precision high-speed atomic force microscopy.

Atomic force microscopy (AFM) enables nanoscale characterization and has been widely applied to a broad range of systems. Over the past two decades, advances in high-speed AFM have enabled not only the imaging of static structures but also the direct observation of nanoscale dynamics in real time. However, because the tip or sample is typically scanned using piezoelectric actuators, nonlinearities in their response to the input signal can introduce image-scaling errors of up to 20-30%. Consequently, there is a strong demand for a method to correct piezoelectric nonlinearity that can reliably support quantitative dynamic structural measurements. Here, we propose a simple software-based feedforward method to generate scan waveforms that can be readily implemented. We identify four distinct sources of positioning error in piezo scanners and demonstrate that these errors can be compensated, achieving an order-of-magnitude improvement in positioning accuracy compared with uncompensated operation. Because the proposed method is software-based and requires no additional hardware, it preserves imaging speed and is well suited for high-speed AFM. It is also compatible with a wide range of AFM and other scanning probe systems.