Parameters
wx : half width of the incident beam waist in the XZ plane
wy : half width of the incident beam waist in the YZ plane
z : distance from the waist
lam : wavelength
zox : Rayleigh range in the XZ plane
zoy : Rayleigh range in the YZ plane
wx_z : half width of the beam in the XZ plane at a distance z from the waist
wy_z : half width of the beam in the YZ plane at a distance z from the waist
divx : half divergence of the beam in the XZ plane
divy : half divergence of the beam in the YZ plane
Rx_z : wavefront radius in the XZ plane
Ry_z : wavefront radius in the YZ plane
