INFRARED THREE-LENS OBJECTIVE Russian patent published in 2018 - IPC G02B13/14 G02B9/16 

FIELD: physics.

SUBSTANCE: objective contains three menisci, the first of which is positive, the second one - negative, the third one - positive. All menisci face the image plane with their concave surfaces. The concave surface of the first meniscus is aspherical with a conical constant ranging of 0.28 to 0.52. The first meniscus is made of germanium, the second one is made of chalcogenide glass IRG-22 or IRG-25, and the third one is made of IRG-26 chalcogenide glass or IKS-25 oxygen-free glass. The following relations are hold: ϕ₁ = (0.77÷1.00)ϕ, ϕ₂ = -(2.00÷2.45)ϕ, ϕ₃ = (2.80÷3.20)ϕ, where: ϕ₁, ϕ₂, ϕ₃ - the relative optical forces of the first, the second, and the third menisci, respectively; ϕ - the optical power of the objective. D2 = (0.58÷0.86)f', where: D2 - the air gap between the first and the second menisci; f' - the focal length of the objective.

EFFECT: increasing the processability of the objective, improving the image quality, reducing the size and weight of the objective.

2 tbl, 6 dwg