Total internal reflection–fluorescence correlation spectroscopy (TIR-FCS) is an emerging technique that is used to measure events at or near an interface, including local fluorophore concentrations, ...

In TIRF microscopy, fluorescent molecules are in a sample in an aqueous environment that is near a solid with a high refractive index, usually a glass coverslip. At what is called the critical angle, ...

Such a thick layer can be observed when the liquid is held within a transparent container and the observer is looking at the top most portion of the liquid from the sides of the transparent container.