Fluorescence polarization filtering for accurate single molecule localization

Single-Molecule Localization Microscopy (SMLM) has become one of the most important methods of super-resolution fluorescence microscopy. It is based on the precise localization of single molecules in wide-field microscopy images. It is well known that the localization accuracy can show a significant bias if the imaged molecules have a fixed orientation and are located either close to an interface or not exactly within the focal plane of the microscope. In this Letter, we propose a simple solution to this problem, which is based on polarization-resolved imaging. This method can be easily implemented into any existing SMLM setup, and we demonstrate its performance by imaging single dye molecules embedded into a polymer film, which fixes their orientation in space.