The refractive index of the ice at the laser wavelength must be known
in order to measure the thickness. In our method of computation the refractive
index of the film is derived from the amplitude of the interference curve.
Transmittance spectra were taken at different thicknesses (0.05-3 micrometers) with the electric vector parallel (p polarized) and perpendicular (s polarized) to the incidence plane. Optical constants have been derived, using a non-linear least squares method, in such a way they satisfy the Kramers-Kronig relation and give the best agreement with the transmittance spectra at oblique incidence for p and s polarizations measured at different thicknesses. This procedure can clearly seperate the contribution of n and k to the spectrum. The experimental set-up, the method of computation and the theoretical model are described in detail in the following article:
G.A. Baratta and M.E. Palumbo, Infrared optical constants of CO and CO2 thin icy films, JOSA A, 15, 3076-3085, 1998. Please refer to this article when using datafiles from this page.
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