High-speed large-range dynamic-mode atomic force microscope imaging: Adaptive tapping approach via Field Programmable Gate Array

This paper presents a software-hardware integrated approach to high-speed large-range dynamic mode imaging of atomic force microscope (AFM). High speed AFM imaging is needed to interrogate dynamic processes at nanoscale such as chemical reactions. High-speed dynamic-modes such as tapping-mode AFM imaging are challenging as the probe tapping motion is highly sensitive to the highly nonlinear probe-sample interaction during the imaging process. The existing hardware-based approach via bandwidth enlargement, however, results in a substantialy restricted imaging area that can be covered. Contrarily, software-based approach, for example, the recently developed adaptive multiloop mode (AMLM) technique has demonstrated its efficacy in increasing the tapping-mode imaging speed without loss of imaging size. However, further improvement has been limited by the the hareware bandwidth and the online signal processing speed and computation complexity.Thus, in this paper, the AMLM technique is furhter enhanced to optimize the probe tapping regulation and integrated with the FPGA platform to further increase the imaging speed without loss of imaging quality and range. AFM imaging experiment is presented and discussed to illustrate this integrated approach.