A.R. Bestugin – Dr.Sc.(Eng.), Professor, Director of Institute of radio engineering, electronics and communication  of Saint-Petersburg State University of Aerospace Instrumentation
E-mail: fresguap@mail.ru

Yu.A. Novikova – Ph.D.(Phys.-Math.), Associate Professor, Department of Physics, 
Saint-Petersburg State University of Aerospace Instrumentation
E-mail: Nov-Jliana@yandex.ru

M.B. Ryzhikov – Ph.D.(Eng.), Associate Professor, Department of Radio Technical and Optoelectronic Complex, Saint-Petersburg State University of Aerospace Instrumentation
E-mail: maxrmb@rambler.ru

I.A. Kirshina – Ph.D.(Econ.), Associate Professor, 
Saint-Petersburg State University of Aerospace Instrumentation
E-mail: zlata@aanet.ru

The relevance of the researches conducted in work is connected with need of increase in efficiency, reliability and increase in terms of operation of the radio optical systems working in real atmospheric conditions. The film coverings of optical antennas applied now used on reception and radiation in the infrared range of lengths of waves demand increase in moisture resistance and mechanical durability at temperature influences. It is connected with the fact that the most often used films of BaF2 fluorides which are characterized by low index of refraction in infrared area of a range are unstable at temperature drops. Increase in operational characteristics has to be realized without deterioration in their optical transparency as it is possible in wider part of a range of near and average infrared range of lengths of waves. It demands search and introduction in structure of multilayered interferential coverings of films from the new perspective materials increasing reliability indicators. It is impossible to prove prospects of application of such films without research of their optical properties. For definition of their optical constants the spektrofotometrichesky method based on the analysis of ranges of reflection and transmission of films is used. Existence of strips of absorption distorts ranges of reflection and transmission and complicates definition of optical constants. In work was the experimental calculation method which allows to consider effect of absorption is used and to receive more exact estimates of the studied parameters. On its basis results of theoretical calculations and experimental measurements for the new film executed from SrYF4 which can serve for creation of the highly effective clarifying coverings in the range of lengths of waves from 1.3 to 12 microns are received.

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