Filtration of IR radiation by three-component polymer-crystalline systems

We have investigated the regularities in forming the spectral characteristic of three-component polymeric-crystalline polytetrafluorethylene-Ge-LiF interference systems in the wide IR spectral region 0.8–160 µm. The efficiency of suppressing short-wave radiation by structurally asymmetric imerference systems consisting of polytetrafluorethylene and quasihomogeneous layers with a high refractive index is shown. Two of this kind of three-layer systems are sufficient for suppressing background radiation within the wavelength interval from the visible range to ∼35 µm owing to multiple reflection at the boundaries of elementary Ge and LiF layers that form quasihomogeneous layers (λ ∼ 1.7–17.0 µm) and also due to absorption in the Ge (λ<1.7 µm) and Lif (λ ∼ 17–35 µm) layers.