Sellmeier dispersion equation

The index of refraction of synthetic vitreous siUca at 20°C has been fitted to a three-term Sellmeier dispersion equation for wavelengths from 0.2139 to 3.7067 pm (184), where n is the refractive index and X is the corresponding wavelength in micrometers. 

Refractive Index. The refractive indices of the bulk polymers were measured by using an Abbe s refractometer at room temperature. In order to measure the refractive indices at several wavelengths, an interference filter was inserted in the refractometer. Two or three measurements were made at each wavelength and averaged. Usually, the refractive-index data were fit to a three-term Sellmeier dispersion equation of the form (P) ... 

Dispersion of the refractive index of the amorphous film can be analyzed based on the Sellmeier equation,as follows ... 

From Tables 3, 5, and 6 it is seen that refractions change in some inverse manner with the wave-length A of the light by which they are measured the variations originate, of course, in the refractive indices entering the Lorentz-Lorenz function (1). Since 1827, a number of equations have been developed to describe dispersions of refractive indices n (Wood, 1934, and Partington, 1953, give historical and other details) of these, those due to Cauchy (9) and Sellmeier (10) appear to be best known and most used... 

Conventional polymers, in general, show ordinary dispersion, in which the orientation birefringence increases with the wavelength. This behavior can be expressed by the following equation, which was proposed based on the Sellmeier relation [20-22], as follows ... 

The Sellmeier equation is a later development of Cauchy s work that handles anomalously dispersive regions, and more accurately models a material s refractive index across the ultraviolet, visible, and infrared spectrum. 

Sellmeier Equation An empirical relationship between refractive index and wavelength for a particular transparent medium. The equation is used to determine the dispersion of light in the medium. It was first proposed in 1871 hy W. Selhneier, and was a development of the work of Augustin Cauchy on Cauchy s equation for modeling dispersion. 

The usual form of the equation for glasses is n2(A) = i+ + +, where n is the refractive index, X is the wavelength, and Bi,2,3 and Q.2.3 are experimentally determined Sellmeier coefficients (Schott (2007) Refractive index and dispersion. Technical information document TlE-29). These coefficients are usually quoted for X in micrometers. Note that this X is the vacuum wavelength not that in the... 

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