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State-of-the-art atomic force microscopes (AFMs) are designed to capture images of structures as small as a fraction of a nanometer - a million times smaller than the width of a human hair. Atomic force microscopes typically scan samples using an ultrafine probe, or needle, that skims along the surface of a sample, tracing its topography, similarly to how a blind person reads Braille.
http://news.mit.edu/2015/new-microscope-real-time-videos-nanoscale-1214