Parameters
n0 : refraction index of the first medium
n1 : refraction index of the second medium
R : radius of curvature of the surface
x : distance from the surface vertex to the object
D : aperture diameter (located on the refracting surface)
xi : distance from the surface vertex to the image
m : magnification
NA : numerical aperture in the object space
NAi : numerical aperture in the image space
