% File: http://web.mit.edu/8.13/matlab/Examples/singleslit.m % Date: 2008-June-13 % Author: Scott Sewell %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % From Eugene Hecht's Optics: 4th Edition, Equation 10.17 % singleslit(b,l,f) plots the single slit diffraction pattern for % a slit of width 'b' in mm % a wavelength of 'l' in nm % a slit-to-screen distance of 'f' in m. % Produces a plot of intensity versus screen position in mm. % I(theta) = I(0)sinc^2(Beta) where Beta = pi b/l % One can see that 'Beta' is a relative measure of the width of the % diffracting slit and the wavelength of light %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% b1=.1; b2=.05; l=632; f=0.5; theta=[-.02:.0001:.02]; beta1=pi*(b1/1000)/(l/1e9).*sin(theta); beta2=pi*(b2/1000)/(l/1e9).*sin(theta); y1=(sin(beta1)./beta1).^2; y2=(sin(beta2)./beta2).^2; plot(theta*f*1000,y1); hold on; plot(theta*f*1000,y2,'--'); legend('100\mum slit','50 \mum slit'); title('Diffraction pattern from a HeNe laser through a single slit at 50cm distance'); xlabel('Position on Screen [mm]') ylabel('Intensity');