ATHERMALISED HIGH-APERTURE INFRARED LENS Russian patent published in 2016 - IPC G02B13/14 G02B9/34 

FIELD: instrument making.

SUBSTANCE: invention can be used in imaging devices. Lens comprises four single menisci whose concave side faces image. First meniscus is positive, second is positive, made from material with negative temperature coefficient of refraction index, third is negative, made from material with positive temperature coefficient of refraction index and low value of dispersion, fourth is positive. Between focus distances of lenses, following relationships are satisfied: F₁/F₀ = 1.7÷2.2; F₀/F₂ = 0.15÷0.55; |F₃|/F₀ = 1.6÷3.0; F₄/F₀ = 0.6÷1.0; where F₁, F₂, F₃, F₄, F₀ - focal distances of first, second, third, fourth components and lens respectively.

EFFECT: technical result is lens image quality improvement over a wide temperature range with a large relative aperture and field of view angle.

6 cl, 6 dwg, 1 tbl