function [Mt, Ms] = TTflipped(R, a1)
% [Mt, Ms] = TTflipped(R, a1)

if length(R) > 1
    Rt = R(1);
    Rs = R(2);
else
    Rt = R;
    Rs = R;
end

% index of refraction
N = 1.45;

% mirror thickness
thickness = (3/8)*0.0254;

% RoC of AR surface
R_a = Inf;

% incident and transmitted angles in radians
a1r = a1*pi/180;
a2r = asin(sin(a1r)/N);
a2 = a2r*180/pi;

% initial transmission at AR
[Mari_t, Mari_s] = transmission(R_a, a1, 1, N);

% propagation through bulk
L = thickness/cos(a2r);
Mbulk = [1 L/N; 0 1];

% reflection at HR
[Mhr_t, Mhr_s] = mirror(R, a2, N);

% exit transmission at AR
[Mare_t, Mare_s] = transmission(-R_a, a2, N, 1);

% overall M
Mt = Mare_t * Mbulk * Mhr_t * Mbulk * Mari_t;
Ms = Mare_s * Mbulk * Mhr_s * Mbulk * Mari_s;