STED Microscopy

Synopsis

Optical microscopy is a crucial tool for biological studies of cells and processes therein. In the imaging process, diffraction sets a lower limit on the achievable resolution, which corresponds to a limit of 200nm for optical microscopy. For a long time, modern microscopes have been diffraction limited. STED (STimulated Emission Depletion) microscopy is able to overcome the resolution limit by changing the way in which the sample is illuminated. Fluorescent dyes in the sample are excited and relaxed such that only a well-localized region of the sample fluoresces at a time. Since this excited region can be shrunk arbitrarily, a diffraction limited apparatus can produce images below the diffraction limit.