Refraction close refractionProcess by which a wave changes speed and sometimes direction upon entering a denser or less dense medium, eg a light ray changes direction when refracted by a lens. from a ...

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, ...

However, if this would bring the ray out at more than 90° from the normal, the refraction is not possible. In this situation, the ray is reflected inside the more dense medium, following the law of ...