blob: 347d60be5130b229303643e858ffa9f955de737b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
|
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
|
