Dear thin film experts,

I'm looking for an incoherent (multiple beam interference by summing
up the intensities and not the field amplitudes) emissivity model for
a film on a substrate (e.g. the system substrate/film/air) which
converges (!) towards the emissivity of the substrate for decreasing
film thickness.

Does anyone know how the different situations 'film'
and 'no film' can be modelled? Mostly an indirect approach is used
('e=1-R').

Does anyone have experience with the direct McMahon-type
incoherent emissivity model?

I have the problem that using the incoherent approach by
Gardon/McMahon (due to Pigeat et al., Phys.Rev.B, vol.57, 15,
pp.9293-9300 (1998) and Alok/Thakur, Appl. Energy 15, pp.1-13 (1983))
I don't get the result presented by Pigeat et al.

Thanks in advance!