WIDE-ANGLE INFRARED LENS Russian patent published in 2018 - IPC G02B13/14 G02B9/34 

FIELD: optics.

SUBSTANCE: lens can be used in thermal imagers sensitive in spectral range from 8 to 12 mcm. Lens contains four meniscus, of which the first, second and fourth in the course of the ray are positive, and the third is negative. All meniscus by concave surfaces face image plane. Concave surface of the first meniscus is aspherical with a conical constant ranging from 2 to 14. First and fourth meniscuses are made of germanium, the second - from oxygen-free glass IKS-25 or from chalcogenide glass IRG-26, the third – from zinc selenide. Air gaps between the first and second, second and third menisci are no more than 0.06 focal length of the lens. Following relationships are satisfied: ϕ₁=(0.42÷0.58)ϕ, ϕ₂=(0.04÷0.33)ϕ, ϕ₃=-(0.32÷0.48)ϕ, ϕ₄=(1.17÷1.27)ϕ, where: ϕ₁, ϕ₂, ϕ₃, ϕ₄ – relative optical forces of the first, second, third and fourth menisci, respectively; ϕ – optical power of the lens.

EFFECT: expansion of the field of view without deteriorating image quality.

1 cl, 5 dwg, 1 tbl