function [R, theta_t] = fresnel_reflection(n1, n2, theta_i) %% calculates intensity reflection coefficient for s and p polarizations %% for light travelling from material with index of refraction n1 to material with n2 %% theta_i - incident angle in medium 1 with respect to normal, could be a vector %% R - coefficients of reflection array [Rs, Rp] %% theta_t - transmitted/refracted angle in medium 2 with respect to normal if ( size(theta_i)(1) != 1) error('theta_i must be a vector or scalar'); end %% see http://en.wikipedia.org/wiki/Fresnel_equations %% refraction angle or angle of transmitted beam with respect to normal sin_theta_t=n1/n2*sin(theta_i); %% special cases: total internal reflection indx = (abs(sin_theta_t) >= 1); sin_theta_t( indx ) = sign( sin_theta_t(indx) ); theta_t = asin(sin_theta_t); % angle of refraction or transmitted beam cos_theta_t = cos( theta_t ); cos_theta_i = cos( theta_i ); Rs = ( ( n1*cos_theta_i - n2*cos_theta_t ) ./ ( n1*cos_theta_i + n2*cos_theta_t ) ).^2; Rp = ( ( n1*cos_theta_t - n2*cos_theta_i ) ./ ( n1*cos_theta_t + n2*cos_theta_i ) ).^2; R = [Rs; Rp]; end