fluorescence microscopy fluorescence microscopy assay total internal reflection fluorescence microscopy TIRFM TIRF microscopy Microscopy where the specimen (a fluorophore) can be made to fluoresce (emit energy as visible light) by illuminating it with light of specific wavelength. The light is totally internally reflected to generate an evanescent wave at the glass microscope slide-water interface. The evanescent wave selectively illuminates and excites fluorophores in a restricted region of the specimen allowing fluorophores on the surface to be imaged (normally the fluorescence of surface fluorophores is overwhelmed by background fluorescence). CHMO:0000094