Fluorescence can be characterized by its intensity, position, wavelength, lifetime, and polarization. The more of these features are acquired in a single measurement, the more can be learned about the sample, i.e., the microenvironment of the fluorescence probe. Polarization-resolved fluorescence lifetime imaging-time-resolved fluorescence anisotropy imaging, TR-FAIM-allows mapping of viscosity or binding or of homo-FRET which can indicate dimerization or generally oligomerization.