SPECKLE computes size of speckle pattern
SYNTAX; speckle;
by Chuck DiMarzio Northeastern University August 2009
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Light from a laser is focused to a spot on a ground glass. We want to know the size of the speckles on a screen some distance away.
Contents
Set parameters
lambda=532e-9; % Doubled Nd:YAG d0=2.7e-6/2; % Waist diameter with NA=0.25 b=pi*d0^2/4/lambda; % Rayleigh range z=(-5:0.05:5)*b; % Vary z through focus zscreen=0.3; % Distance to screen %
Compute beam diameter at glass, speckle diameter, and plot
dglass=d0*sqrt(1+(z/b).^2); % beam diameter on the glass dspeckle=4/pi*lambda./dglass*zscreen; % speckle diameter on the screen % fig1=figure;plot(z*1e6,dspeckle*1e3);grid on; moose=axis; axis([moose(1:2),0,moose(4)]); xlabel('z, Distance from Focus, \mu m'); ylabel('d_{speckle}, mm');
