Also employed in binoculars and fiber optics, FTP, name this phenomenon in which light rays approaching a boundary between two media at angles greater than the critical angle remain within the medium with a higher index of refraction.
Microscopes employing this phenomenon are used to observe single fluorescent molecules and detect their distance from a flat surface.  Such microscopes take advantage of the Goos-Hanchen effect, also known as the "frustrated" form of it, in which a small amount of the energy in an evanescent wave is slightly scattered by the presence of a sphere with a different refractive index.  Also employed in binoculars and fiber optics, FTP, name this phenomenon in which light rays approaching a boundary between two media at angles greater than the critical angle remain within the medium with a higher index of refraction.
Microscopes employing this phenomenon are used to observe single fluorescent molecules and detect their distance from a flat surface.  
total internal reflection