We investigated the resonant absorption capacity of a one-dimensional photonic crystal, the relationship between the resonant frequency and the width of its absorption band, and the composition and thickness of the layers forming it. Frequency oscillations of radiation reflection from 2.5-layer semimetal-dielectric-metal film structures caused by interference on the film thickness were studied. We measured the infrared reflection spectra of Bi87Sb13 film samples on mirror-smooth substrates with a reflective metal (Al, Ti) layer and a dielectric layer MgF2+LiF or SiO2+Si3N4). We have developed samples that absorb up to 99.5% of radiation at maximum and integrally up to 60% of resonant thermal radiation. The composition of structures for interfacing with silicon technologies and constructing matrices of sensitive bolometric receivers has been optimized. We have proposed the implementation of active selective thermal imaging systems with matching the source and receiver of radiation simultaneously in frequency and frequency band. The analogy of the absorbing properties of film structures and the properties of human eye cells was shown. Keywords: bismuth, film, IR, interference, eye color sensitivity.

The infrared transmission and reflection spectra of a series of samples of bismuth films of different thicknesses on identical single-crystal silicon substrates were measured. Transmission and reflection oscillations caused by interference on the film thickness are investigated. Properties of Si-plates are estimated. Refractive index and absorption index of bismuth are calculated. Keywords: bismuth, film, IR, interference.