This tutorial explains the principles of STED super-resolution microscopy - from the underlying photo physical processes to the integration into a confocal laser scanning microscope. STED microscopy reduces the area of emitting fluorochromes to sub-diffraction sizes. This reduction is achieved by using the phenomenon of stimulated emission, which was proposed already by A. Einstein and is the basic concept of laser technology. As the focus of the de-exciting light is shaped like a ring (by means of phase-shifted interference), the residual emitting area is circular and much smaller compared to the diffraction limited origin.
Stimulated emission is based on the interplay of fine optics and photo physical processes and delivers super-resolution in a purely optical way – on a confocal platform.