Real time estimation of equivalent cantilever parameters in tapping mode atomic force microscopy

In this article, a method of imaging is developed, where during tapping-mode operation, equivalent resonant frequency and quality factor can be obtained in real time. It involves exciting the cantilever near its resonant frequency and two other frequencies chosen close to the resonant frequency. It is shown that changes in equivalent cantilever parameters can be registered for topography changes that are less than 1 nm in height and within 400 μs of the change occurring. The estimation time is two orders of magnitude better than current techniques.