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The refractive index or index of refraction of a substance is a dimensionless number that describes how light, or any other radiation, propagates through ... more

The angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. ... more

A guided ray (also bound ray or trapped ray) is a ray of light in a multi-mode optical fiber ( type of optical fiber mostly used for communication over ... more

The refractive index is used for optics in Fresnel equations and Snell’s law; while the relative permittivity and permeability are used in ... more

The Fresnel equations (or Fresnel conditions) describe the behaviour of light when moving between media of differing refractive indices. The reflection of ... more

In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can ... more

A lens is a transmissive optical device which affects the focusing of a light beam through refraction. A simple lens consists of a single piece of ... more

Cherenkov radiation, also known as Vavilov–Cherenkov radiation,[a] is electromagnetic radiation emitted when a charged particle (such as an electron) ... more

When an electromagnetic wave travels through a medium in which it gets attenuated (this is called an “opaque” or “attenuating” ... more

The Sagnac effect (also called Sagnac interference), named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is ... more