Parameters
R1 : radius of curvature of the first surface
R2 : radius of curvature of the second 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 )
e : center thickness
n0 : refraction index of the first medium
n2 : refraction index of the last medium
n1 : refraction index of the lens
x : distance from the apex of the first surface to the object point
l : longitudinal spherical aberration
dy : transversal spherical aberration
