Stefan W. Hell is a German physicist, director of the Max Plank Institute for Biophysical Chemistry in Göttingen, Germany. Born in Romania, he did his undergraduate and postgraduate studies in Heidelberg, where he received his doctorate in 1990. It was during his postgraduate project with Siegfried Hunklinger that he became interested in ways to improve the resolution of confocal and fluorescence microscopy, and this became the focus of his research activity in the following years.
From 1991 to 1993, he stayed in Heidelberg to work at the European Molecular Biology Laboratory. There, he developed the fundamentals of 4Pi-microscopy, which allows improving the axial resolution of a confocal microscope.
Toward the end of 1993, he moved to Turku, in Finland, where he led his own research group in the Department of Medical Physics. During this period, he proposed stimulated emission depletion (STED) microscopy, which would later break the 200 nm barrier in resolution established by Ernst Abbe over a century before.
In 1997, he went back to Germany, this time in Göttingen at the Max Plank Institute for Biophysical Chemistry, where he established the Nanophotonics department and where he became a director in 2002. In Göttingen, he further developed STED microscopy and focused on other microscopy techniques derived from it. His interests are still in improving microscopy techniques and in applying them to study biological systems. For his pioneering work on microscopy, he has been awarded numerous prizes, including the Prize of the International Commission in Optics in 2000, the Otto-Hahn-Prize in 2009, the Gothenburg Lise-Meitner Prize, and the Körber European Science Award in 2011.