M.V. Koltsov, A.S. Raevskii, S.B. Raevskii

Application of Fresnel lenses, which unlike conventional lenses have a complex stepwise structure, can be one solution to the problem of focusing the cosmic microwave background radiation at the ultra-sensitive sensors. Fresnel lenses as the focusing element for the electromagnetic radiation at ultra-sensitive sensors can be used in BOOMERanG, Millimetron and other projects. The description of the ray-trace method of calculation and analysis of the Fresnel lenses, the algorithm of the calculation program and the simulation results based on this method are given in the paper. The highly specialized software that allows simulating the path of the rays in the source-lens system was realized to solve the problem of the optimal Fresnel lens creation. Three versions of Fresnel lenses were considered: two collecting and one scattering. For each the ribbed surface profile was calculated for a different number of faces and different focal length. The ray path in the lenses was considered. The effectiveness of the power transmission of radiation through the lens, the uniformity of the radiation after passing through the lens and especially the passage of waves with different polarizations were estimated. The results of these investigations may be useful for the design of the terahertz antenna systems.