The FAST module: an add-on unit for driving commercial scanning probe microscopes at video rate and beyond.

We present the design and the performance of the FAST (Fast Acquisition of SPM Timeseries) module, an add-on instrument that can drive commercial scanning probe microscopes (SPM) at and beyond video rate image frequencies. In the design of this module, we adopted and integrated several technical solutions previously proposed by different groups in order to overcome the problems encountered when driving SPMs at high scanning frequencies. The fast probe motion control and signal acquisition are implemented in a way that is totally transparent to the existing control electronics, allowing the user to switch immediately and seamlessly to the fast scanning mode when imaging in the conventional slow mode. The unit provides a completely non-invasive, fast scanning upgrade to common SPM instruments that are not specifically designed for high speed scanning. To test its performance, we used this module to drive a commercial scanning tunneling microscope (STM) system in a quasi-constant height mode to frame rates of 100 Hz and above, demonstrating extremely stable and high resolution imaging capabilities. The module is extremely versatile and its application is not limited to STM setups but can, in principle, be generalized to any scanning probe instrument.