% reseau de diffraction close all clear rad = 180/pi; % une longueur d'onde lambda = 700e-9 N = 4000 a = 0.01 / N b = 0.5e-6 theta_i = 10/rad; theta = [-1 : 0.00001 : 1]; beta = pi*b/lambda * sin(theta + theta_i); alfa = pi*a/lambda * (sin(theta) + sin(theta_i)); I = 1/ N^2 * (sinc1(beta)).^2 .* (sin(N*alfa) ./ sin(alfa)).^2; figure plot (theta*rad,I,'r'); xlabel ('\theta (deg)'); grid on tit = ['\lambda = ' num2str(lambda*1e9) ' nm - a = ' num2str(a*1e6) ' \mum - b = ' num2str(b*1e6) ' \mum']; title (tit) figure; plot(alfa/pi,I, 'r'); xlabel ('\alpha/\pi') title ('diagramme avec échelle \alpha/\pi') % plusieurs longueurs d'onde lam = [450:50:700]*1e-9 col = 'bcgymr'; figure; hold on for i = 1:length(lam) beta = pi*b/lam(i) * sin(theta + theta_i); alfa = pi*a/lam(i) * (sin(theta) + sin(theta_i)); I(i,:) = 1/ N^2 .* (sinc1(beta)).^2 .* (sin(N*alfa) ./ sin(alfa)).^2; plot (theta*rad, I(i,:), col(i)) end xlabel ('\theta (deg)'); hold off; grid on; legend ('bleu','turquoise','vert','jaune','orange','rouge')