function [n] = computeRefractiveIndexFromSellmeierCoefficients(wavLen,B1,B2,B3,C1,C2,C3)  
% computes the refractive index of glass from its sellmeir coefficients
% all the coeffifints are in sq. µm and the wavelength in µm
n = sqrt(1 + ((B1*wavLen^2)/(wavLen^2 - C1)) + ((B2*wavLen^2)/(wavLen^2 - C2)) + ((B3*wavLen^2)/(wavLen^2 - C3)));
