Conventional fluorescence microscopy is a versatile tool to perform functional cell biology analysis. Fluorophores are being coupled to antibodies which bind to their corresponding proteins in the cell. By analyzing the fluorescence signals in the microscopy image, one can get insight to  the distribution of the chosen proteins inside the cell.

However, in terms of nano-science and detailed insight into biological processes on a molecular level, convential fluorescence microscopy is stretched to its limit.

In an epifluorescence microscope the lateral resolution is determined by the diffraction limit, i.e. you cannot distinguish two molecules having a distance less than ~200nm from each other. In a confocal setup it is possible to improve the resolution slightly, but not sufficient to detect single molecules.

In Conventional Fluorescence Microscopy the Full-Width-at-Half-Maximum (FWHM) of the Point-Spread-Function (PSF) >200nm. Signals of adjacent dyes overlap, therefore single molecules cannot be resolved

Using SPDM, randomly activated dyes are „optically isolated“, i.e. no overlap of the signal of adjacent molecules can occur

The locations of the optically isolated fluorophores are determined by the localization algorithm with a precision down to 20nm

All localizations found in a stack of usually ten thousands of images are displayed in a single reconstructed super-resolved image