Parameters
R : radius of curvature of the refracting surface
D : clear aperture of the refracting surface ( located on the surface and not in the plane tangent to the surface and passing through the apex S )
n0 : refraction index of the first medium
n1 : refraction index of the second medium
x : distance from the refracting surface apex to the object point
l : longitudinal spherical aberration
dy : transversal spherical aberration
