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Date 06/09/2010
Script S4_2_8.m
Download Script S4_2_8.m
%==============================================
%Fabry_Perot interferometer 1
%==============================================
%
%the wavelength 0.435 microns (the blue line of a mercury-vapor lamp)
lambda=0.435;
%the thickness d in microns
d=1e+003;
%angles of incidence in degrees and in radians
tetag=0.5:0.0001:3;
teta=tetag*(pi/180);
%the very large number max of the angles
max=length(teta)
%three values of reflexivity
ro=[0.3 0.6 0.9];
%
%the array with 3 row and max columns is initialized
%setting zero values in all positions
Ir=zeros(3,max);
%
%==============================================================
%values of Ir for different reflexivity are computed
for j=1:3
ro1=ro(j);
j
%corresponding values od refractivity
%and their squares
tau1=1-ro1;
ro1q=ro1^2;
tau1q=tau1^2;
%
%maximum of Ir is always equal to one
%
%the minimum is given by the following formula
%for the assigned value of reflectivity
minIr=tau1q/((1+ro1)^2)
%
%corresponding phase shifts fi
k=2*pi/(lambda);
fi=(k*2*d)*cos(teta);
%the relative intensity Ir
num=tau1q;
den1=1+ro1q;
den2=2*(ro1*cos(fi));
den=den1-den2;
%the row j is set to values of Ir for the assigned reflexivity
Ir(j,:)=num./den;
end
%==============================================================
%
%plots of Ir for the considered reflexivity
plot(tetag,Ir(1,:),'r-')
title('Ir when ro is 0.3. Now minimum is about 0.29'),figure
plot(tetag,Ir(2,:),'b-')
title('Ir when ro is 0.6. Now minimum is about 0.06'),figure
plot(tetag,Ir(3,:),'g-')
title('Ir when ro is 0.9. Now minimum is about 0.001')
%==============================================
%
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