Fig. 2.5.

TIRF microscopy visualizes virions bound on the membrane surface (gray) within a 100 nm deep evanescent wave (green). Fluorophores in unbound virions are not excited by the evanescent wave, while virions bound to the bilayer are illuminated, denoted here by the bright red color in the center cartoon. Residence times can be determined by the number of frames the virion remains observable, as shown in the images below the cartoons, before the virion unbinds