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From: sumane@anaconda.stanford.edu (Thilaka Sumanaweera)
Newsgroups: comp.graphics
Subject: Re: ray tracing refraction
Message-ID: <6517@polya.Stanford.EDU>
Date: 31 Jan 89 22:19:40 GMT
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Reply-To: sumane@anaconda.stanford.edu (Thilaka Sumanaweera)
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Organization: Stanford University
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> Is index of refraction linear with wavelength?

Maxwell's equations yeild the following:
Complex index of refraction of a given material:

		M = n - jK

where,	n = m  e  { 1 + sqrt[ 1 + square( L s / 2 pi c e) ] } / 2
             r  r

	K = m  e  { -1 + sqrt[ 1 + square( L s / 2 pi c e) ] } / 2
             r  r



	m = Relative permeability of the material
         r
	
	e = Ralative permittivity of the material
         r
	L = wavelength of light
	s = conductivity of the material
	pi= 3.14...
	c = speed of light in the material
	e = permittivity of the material

Source: Principles of Optics - Born and Wolf, Pergamon Press 1959

For dielectric materials like glass, s = 0. Therefore K = 0
leaving only the real part for a good approximation.

Hope this is helpful.

Thilaka