Discrete and Continuous Models and Applied Computational ScienceDiscrete and Continuous Models and Applied Computational Science2658-46702658-7149Peoples' Friendship University of Russia named after Patrice Lumumba (RUDN University)2518310.22363/2658-4670-2020-28-4-378-397Research ArticleSolving the inverse problem for determining the optical characteristics of materialsLovetskiKonstantin P.<p>Candidate of Physical and Mathematical Sciences, assistant professor of Department of Applied Probability and Informatics</p>lovetskiy-kp@rudn.ruZhukovAndrey A.<p>PhD, lead analyst of “ITL Consulting” company</p>a.zhukov@itlc.ruPaukshtoMichael V.<p>- DSc., Physics & Mechanical Engineering, co-founder and CTO of Fibralign Corporation</p>mpaukshto@fibralignbio.comSevastianovLeonid A.<p>Doctor of Physical and Mathematical Sciences, professor of Department of Applied Probability and Informatics</p>sevastianov-la@rudn.ruTiutiunnikAnastasiia A.<p>Candidate of Physical and Mathematical Sciences, lecturer of Department of Applied Probability and Informatics</p>tyutyunnik-aa@rudn.ruPeoples’ Friendship University of Russia (RUDN University)ITL ConsultingFibralign Corporation1512202028437839709122020Copyright © 2020, Lovetski K.P., Zhukov A.A., Paukshto M.V., Sevastianov L.A., Tiutiunnik A.A.2020<p>The paper describes a methodology for determining the optical and physical properties of anisotropic thin film materials. This approach allows in the future designing multilayer thin-film coatings with specified properties. An inverse problem of determining the permittivity tensor and the thickness of a thin film deposited on a glass substrate is formulated. Preliminary information on the belonging of a thin-film coating to a certain class can significantly reduce the computing time and increase the accuracy of determining the permittivity tensor over the entire investigated range of wavelengths and film thickness at the point of reflection and transmission measurement Depending on the goals, it is possible to formulate and, therefore, solve various inverse problems: o determination of the permittivity tensor and specification of the thickness of a thick (up to 1 cm) substrate, often isotropic; o determination of the permittivity tensor of a thin isotropic or anisotropic film deposited on a substrate with known optical properties. 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