function[f3,dx3,dy3,x3,y3]=fresnel(f0,M,N,dx0,dy0,z,lambda)
k=2*pi/lambda;
du=1./(M*dx0);dv=1./(N*dy0);
u=ones(N,1)*[0:M/2-1-M/2:-1]*du;
v=[0:N/2-1-N/2:-1]'*ones(1,M)*dv;
f3=ifft(fft2(f0).*exp(-i*pi^2*(u.^2+v.^2)*z));
dx3=dx0;dy3=dy0;
x3=ones(N,1)*[-M/2:M/2-1]*dx3;
y3=[-N/2:N/2-1]*ones(N,1)*dy3;