The mathematical model of the fiber-optic sensor for gas concentration analysis is under study. The sensor is imple-mented as Fabry-Perot interferometer at the end face of the optical fiber by applying a thin polymer film, which permit-tivity depends on the tested gas concentration. It is shown, that a change in the properties of the optical fiber or the at-mosphere permittivity leads mainly to the spectrum contrast changing and does not change the period and the wave-length shift of its comb. The influence of the polymer film thickness, the environment temperature and humidity on the Fabry-Perot spectrum is analyzed. The necessity of using the temperature and humidity compensation sensors is shown. The method, which determines the permittivity in narrow and wide ranges basing on the comb period and the wave-length shift of Fabry-Perot reflection spectrum, is developed. The relative error of measuring the polymer film permit-tivity depending on the film thickness for three wavelength ranges (810−890, 1270−1350, and 1510−1590 nm) is esti-mated. The real achievable relative error in determining the polymer film permittivity is in 0.3–1% FSI, depending on the conditions of the experiment. The mathematical methods and practical recommendations are proposed.
Hussein, S.M.R.H.; Sakhabutdinov, A.Zh.; Morozov, O.G.; Anfinogentov, V.I.; Tunakova, J.A.; Shagidullin, A.R.; Kuznetsov, A.A.; Lipatnikov, K.A.; and Nasybullin, A.R.
"Applicability limits of the end face fiber-optic gas concentration sensor, based on Fabry-Perot interferometer,"
Karbala International Journal of Modern Science: Vol. 8
, Article 5.
Available at: https://doi.org/10.33640/2405-609X.3243
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