function [n]=BK7(wavel)
% Refractive index of glass BK7 using the formula from refractiveindex.info
% The wavelength must be in microns

wavel2=wavel*wavel; % la formule d�pend du carr� de la longueur d'onde
n2=1+(1.03961212*wavel2)/(wavel2-0.00600069867)+(0.231792344*wavel2)/(wavel2-0.0200179144)+(1.01046945*wavel2)/(wavel2-103.560653);
n=sqrt(n2);