Scanning probe microscopy with inherent disturbance suppression

We introduce a general approach for inherently suppressing out-of-plane disturbances in scanning probe microscopy that enables higher-resolution imaging, particularly in noisy environments. In this approach, two distinct sensors simultaneously measure the probe–sample separation. One sensor measures a spatial average over a large sample area while the other responds locally to topography underneath the nanometer-scale probe. When the localized sensor is used to control the probe– sample separation in feedback, the spatially distributed sensor signal reveals only topography. We implemented this approach on a scanning tunneling microscope using a microcantilever with an integrated tunneling tip and interferometer. For disturbances applied normal to the sample, we measure −50 dB of disturbance suppression at 1 Hz, compared to 0 dB with conventional imaging. © 2004 American Institute of Physics. [DOI: 10.1063/1.1812377]