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+%---------------------------------------------------------------
+% PROGRAM: NRI
+% AUTHOR:  Andri M. Gretarsson
+% DATE:    8/5/03
+%
+%
+% SYNTAX: z=NwetonRingsI([w1,w2,R1,R2,P1,P2,lambda,deltaphi],r);
+%
+% Returns the intensity of a set of Newton's rings as a function 
+% of the radial coordinate R. (See e.g. Fundamentals of Physical Optics 
+% by Jenkins and White, 1st ed. Section 4.4).  The Newton's rings are
+% generated by the interference of two coaxial beams with different radii
+% of curvature and/or width.
+%
+% w1       = 1/e field amplitude radius of the 1st of the interfering beams
+% w2       = 1/e field amplitude radius of the 2nd of the interfering beams
+% R1       = Radius of curvature of the phasefront of the 1st of the interfering beams
+% R2       = Radius of curvature of the phasefront of the 2nd of the interfering beams
+% P1       = Radius of curvature of the phasefront of the 2nd of the interfering beams
+% P2       = Radius of curvature of the phasefront of the 2nd of the interfering beams
+% lambda   = Radius of curvature of the phasefront of the 2nd of the interfering beams
+% deltaphi = Radius of curvature of the phasefront of the 2nd of the interfering beams
+% z(k)     = Intensity of the interference pattern at radiusr(k).
+%
+% If x and y are not vectors but matrixes generated by
+% the matlab function meshgrid, then the output variable z
+% is a matrix rather than a vector.  The matrix form allows
+% the function to have a plane as it's domain rather than
+% a curve. To generate a plane domain one uses meshgrid.
+%
+% EXAMPLE:  thetaoffset=20*pi/180;
+%           rseed=[0:0.01:sqrt(0.3)].^2;
+%           thetaseed=[0:1:360]*pi/180;
+%           [theta,r]=meshgrid(thetaseed,rseed);
+%           [x,y]=pol2cart(theta,r);
+%           h=pcolor(x,y,NewtonRingsI([0.01,100,2e3,1e99,1,1,1.024e-6,thetaoffset],r));
+%           colormap('bone');
+%           set(h,'EdgeColor','none');
+%           set(h,'FaceColor','interp');
+%           set(gca,'Visible','off');
+%           set(gcf,'Color','black');
+%           axis square
+%           shg;
+%
+% Last updated: 8/5/03 by AMG
+%
+%---------------------------------------------------------------
+%% SYNTAX: z=NewtonRingsI([w1,w2,R1,R2,P1,P2,lambda,deltaphi],r);
+%---------------------------------------------------------------
+
+function z=NewtonRingsI(params,r)
+
+w1=params(1);
+w2=params(2);
+R1=params(3);
+R2=params(4);
+P1=params(5);
+P2=params(6);
+lambda=params(7);
+deltaphi=params(8);
+a=1/2/R1-1/2/R2;
+
+z = exp(-r.^2/w1).*exp(-r.^2/w2).*...
+    ( sin( (a/2/lambda)* r.^2 - deltaphi) ).^2 + abs(P1-P2);
+\ No newline at end of file