Parameters
wo : radius of the incident beam waist
lam : wavelength
M2 : M square factor (M2)
z : distance from the vertex of the first surface of the lens to the waist of the incident beam
R1 : radius of the first surface of the lens
R2 : radius of second surface of the lens
e : lens thickness
n : refraction index of the lens
wio : half width of the transmitted beam waist
zi : distance from the vertex of the second surface of the lens to the waist of the transmitted beam
