Parameters
lam : wavelength
e : thickness of the Fabry Perot
n : refraction index of the Fabry Perot
k : number of the dark or bright fringe ( counted from the center )
ib : angle of incidence for the bright fringe number k
mb : order of the bright fringe number k
id : angle of incidence for the dark fringe number k
md : order of the dark fringe number k