diffractiongratingspectrum.m

the geometry of a diffraction grating, a common illustration in textbooks of optics, spectroscopy,

% Self-running demonstration of a diffraction grating spectrum
% by addition of sinewaves from the superimposition of 
% reflections from multiple grooves, with phase shift due to incremental 
% path length difference between waves from the adjacent grooves.
% Shows build-up of resultant diffraction pattern as superimposed waves 
% are added.  Note: For a clearer presentation, drag the figure1 
% and figure2 windows so they do not overlap. 
% Tom O'Haver, [e-mail], March 2006
clear
% N = Number of grooves in grating (Try 2 to 30): 
N=10;
% Suggestion: start out with N=2; the "spectrum" is just a sine 
% wave in that case, the ultimate in low resolution!). Then try N=3, 4,
% 5...  what happens as N increases.  Real gratings have N = 1000's
format compact
clf
hold off
start=cputime;
x=[0:.1:pi];  % x-axis for one cycle of sine wave (wavelength=2