The amplitude of the light transmitted by a Michelson interferometer
may be determined by summing the amplitudes resulting from the two
routes through the instrument. If the partially reflecting beamsplitter
divides incident light equally between the two paths, the difference in
path length between the two routes for normal incidence is s, and the
rays of wavelength λ make an angle ϑ to the mirror normals, derive
expressions for the relative amplitudes of these two contributions.
Hence derive the overall fractions of the amplitude and intensity that
are transmitted by the interferometer, as functions of λ, s and ϑ.