Parameters
lam : wavelength
e : thickness of the Fabry Perot
Ref : reflectance of the Fabry Perot surfaces
n : refraction index of the Fabry Perot
i : angle of incidence
FSR : free spectral range
SRW : space between two consecutive resonant wavelengths ( FSR in the wavelength space )
lamFP : closest resonant wavelength to lam
dlam : FWHM for a resonant wavelength
Fin : Finesse of the Fabry Perot
Ref_max : maximum reflectance of the Fabry Perot