Implementation of a Sinusoidal Raster Scan for High-Speed Atomic Force Microscopy

To improve the speed of an atomic force microscope (AFM), one must improve the bandwidth of its components, and the lateral XY scanner is no exception. Sinusoidal raster scans provide a simple way of improving lateral scan rates without the need for additional hardware and/or complex control algorithms. However, a raster scan using a sinusoidal waveform leads to a non-uniform probesample velocity. Uniform spatial sampling of scan data can be achieved in this case by varying the sampling rate as the probe sample velocity varies. In this work, we present a field-programmable gate array (FPGA)-based implementation of a sinusoidal raster scan with uniform spatial sampling for a high-speed atomic force microscope (HS-AFM). Using a home-made HS-AFM scanner and a custom controller, we demonstrate the performance of our approach by imaging Blu-ray disk data tracks in the contact mode. While the results show images comparable to those acquired using the traditional triangular raster scans, mirroring effects are better suppressed in high-speed imaging with sinusoidal scan signals.