Photonics Dictionary: R

A measure of the relative difference in refractive index between two optical materials. Most commonly used in fiber optics where the refractive index contrast, D, is given as follows: where n1 equals...

A closely spaced series of well-known chemicals having a refractive index lying between 1.33 for water and 1.95 for a solution of phosphorus in carbon disulfide. They are used to identify powdered...

The description of the refractive index along a fiber diameter.

The mean square difference in refractive index for two separate points in space.

The ratio of the velocities of light in two adjacent media, neither of which is air.

The quantity equal to the refractive index of one medium divided by that of a second medium.

In gradient index optics, a gradient profile in which the index varies in a direction perpendicular to the optical axis. Radial gradient lenses can focus light even when the lens surfaces are flat,...

Plates of glass containing as many heavy metal oxides as can be dissolved in the glass without causing devitrification. The glass is yellow, very heavy and has a high refractive index. It is almost...

Optical glasses containing the oxides of rare earths such as lanthanum to impart a very high refractive index combined with a low dispersive power.

A device that is used to determine the index of refraction of a gas or liquid through the interference patterns formed by two beams of light, one of which has been transmitted by the sample. A single...

A nonhomogeneity of index in flat glass that is in the form of an approximately plane layer.

Straight line travel. This denotes the fact that light travels in a straight line when traveling through a medium with a constant refractive index.

The ratio of the first focal length of a lens to the refractive index of the medium containing the incident light; the ratio of the second focal length to the refractive index of the medium...

The technique for measuring the index profile of an optical fiber by scanning the entrance face with the vertex of a high numerical aperture cone and measuring the change in power of refracted...

A transparent sphere that has an index of refraction that is different from that of the medium surrounding it; used in optics to demonstrate refraction and astigmatic image formation.

The bending of oblique incident rays as they pass from a medium having one refractive index into a medium with a different refractive index.

An instrument used to measure the refractive index of solids and liquids. Several types exist, the most common being the Abbe refractometer.

The method used to determine the refractive index of a given substance.