Winfried Denk (born 12 November 1957) is a German physicist, director of the Max Planck Institute of Neurobiology in Martinsried, close to Munich. He is noted for being the first to implement two-photon microscopy while a postdoctoral fellow in Watt W. Webb's lab at Cornell University in 1990. Denk later (1994) recognized that two-photon microscopy has unique properties for imaging live cells deep in highly scattering tissues. His second major invention is a machine that automatically acquires three-dimensional images at a resolution of a few nanometers. This technique, known as Serial Block-Face Scanning Electron Microscopy (SBFSEM or SBEM), has been commercialized by the company Gatan.He received Rosenstiel Award in 2013 for their invention of multiphoton fluorescence microscopy and its application to illuminating the function of brain microcircuits.