Parameters
wo : radius of the incident beam waist
z distance from the curved refracting surface vertex to the waist of the incident beam
lam : wavelength
R : radius of the curved refracting surface
n0 : refraction index before the surface
n1 : refraction index after the surface
M2 : M square factor (M2)
wio : radius of the refracted beam waist
zi : distance from the curved refractive surface vertex to the waist of the refracted beam