Sample-profile estimate for fast atomic force microscopy

In this letter, a design scheme that achieves an optimal tip-sample force regulation with an ideal topography image reconstruction is presented. It addresses the problem of obtaining accurate sample profiles when scanning at high bandwidth while maintaining a constant cantilever-tip sample force in atomic force microscopes. In this design scheme, the objective of maintaining a constant tip-sample force while scanning at high bandwidth does not impose limitations on the reconstruction of the sample topography. It is shown that the proposed scheme provides a faithful replica of the sample at all relevant scanning speeds limited only by the inaccuracy in the model for the atomic force microscope. This provides an improvement over existing designs where the sample profile reconstruction is typically bandwidth limited. Comparison with the existing methods of using the control signal as the image is provided. The experimental results corroborate the theoretical development.