| Date 08/09/2010 |
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| Script S4_2_1.m | |||
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%==============================================
%A thin film on a lens %============================================== % %refractive indices %of air n0=1; %of the lens n2=1.85; %a variable refractive index for the layer % %............................................ %a graphical approach %............................................ % m=50; n1=linspace(1,1.85,m); %preliminary calculi for reflectivities num1=(n1-n0); den1=(n1+n0); num2=(n2-n1); den2=(n2+n1); %reflectivity on the surface between air and layer R1=num1./den1; %reflectivity on the surface between layer and lens R2=num2./den2; %theis plots function of the refractive index of the layer plot(n1,R1,'ro-', n1,R2,'bd-'),grid on title('Reflectivity bewteen surfaces air-layer (red) and layer-lens(blue)') axis([1 1.85 0 0.3]) % %............................................ %a numerical approach %............................................ % m1=10000; n11=linspace(1,1.85,m1); num11=(n11-n0); den11=(n11+n0); num22=(n2-n11); den22=(n2+n11); R11=num11./den11; R22=num22./den22; for i=1:m1 diff(i)=abs(R11(i)-R22(i)); end [val,ind]=min(diff) n=n11(ind) %the best value for refractive index of the layer %is 1.3602 %found in the position ind = 4238 %where the difference diff between the two reflectivities %is about 0.00002 %============================================== % |
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