Atomic force microscopy with inherent disturbance suppression for nanostructure imaging

Scanning probe imaging is often limited by disturbances, or mechanical noise, from the environment that couple into the microscope. We demonstrate, on a modified commercial atomic force microscope, that adding an interferometer as a secondary sensor to measure the separation between the base of the cantilever and the sample during conventional feedback scanning can result in real-time images with inherently suppressed out-of-plane disturbances. The modified microscope has the ability to resolve nanometre-scale features in situations where out-of-plane disturbances are comparable to, or even several orders of magnitude greater than, the scale of the topography. We present images of DNA in air from this microscope in tapping mode without vibration isolation, and show improved clarity using the interferometer as the imaging signal. The inherent disturbance suppression approach is applicable to all scanning probe imaging techniques.