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The beam propagates along the Z axis. Its intensity distribution in the plane perpendicular to Z is elliptical and the axis of the ellipse are coinciding with X and Y axis. The beam propagation is calculated independantly in each XZ and YZ plane with the parameters which are effective in the considered propagation plane. In the present case, the beam waists in the XZ and YZ planes are considered to have the same position. The page calculates in each propagation plane the rayleigh range, the half width and divergence of the beam as well as the wavefront radius as functions of the distance to the waist, the half width of the waist and the wavelength.