Supercritical Angle Fluorescence Microscopy

Supercritical Angle Fluorescence Microscopy

Supercritical Angle Fluorescence Microscopy (SAF) is a technique to detect and characterize fluorescent species (proteins, biomolecules, pharmaceuticals, etc.) and their behaviour very close or even adsorbed or linked at surfaces. The method is able to observe molecules in a distance of less than 100 to 0 nanometer from the surface even in presence of high concentrations of fluorescent species around. Using an aspheric lens for excitation of a sample with laser light, fluorescence emitted by the specimen is collected above the critical angle of total internal reflection selectively and directed by a parabolic optics onto a detector. The method was invented in 1998 in the laboratories of Stefan Seeger at University of Regensburg/Germany and later at University of Zurich/Switzerland.