Fast objectives for thermal viewers

This paper discusses the requirements imposed on fast objectives for thermal viewers that operate in combination with detector arrays in the IR region (λ=8-14μm). Based on third-order aberration theory, a technique is proposed for calculating germanium lens objectives. Optical layouts and characteristics are given for a number of specific objectives with relative apertures of D:f′=1:0.75-1:0.8 and angular fields of view of 2ω=10°-60°, developed and fabricated at OAO LOMO.