Parameters
i : angle of incidence
lam : wavelength
no : refraction index of the incident medium
nc : refraction index of the AR coating
n : refraction index of the substrate
k : order of the AR coating layer
th : thickness of the AR coating minimizing the reflection at the given angle of incidence i
Rp : reflectivity for TM polarization
Rs : reflectivity for TE polarization
Run : average reflectivity corresponding to an unpolarized wave
