lda0 0.5[um] Wavelength
k0 2*pi/lda0 "Wave number"
f 150[um] "Focal length"
R f/2 "Radius of curvature of lens surface"
D 50[um] "Lens diameter"
m 1 "Fresnel lens order"
z0 sqrt(R^2-(D/2)^2) "Lens base position in Z"
sag R-z0 "Unfolded lens sag"
n 1.5 "Refractive index"
d m*lda0/(n-1) "Folded lens sag for m-th order"
M 16 "Digitization level"
dm d/M "Step height per level"
N floor(sag/d)+1 "Number of zones"
Nmesh 5 "The number of mesh elements per wavelength"
Nx 256 "Sampling resolution"