INFRARED LENS WITH PASSIVE THERMALIZATION Russian patent published in 2017 - IPC G02B13/14 G02B9/34 

FIELD: physics.

SUBSTANCE: lens contains four menisci fixed in an aluminium alloy casing. The first meniscus is positive, has an aspherical concave surface and is made of germanium. The second meniscus is positive, has an aspherical concave surface and is made of an oxygen-free glass IKS-25 or chalcogenide glass IRG-26. The second meniscus is negative, made of zinc selenide. The fourth meniscus is positive, made of an oxygen-free glass IKS-25 or chalcogenide glass IRG-26. All menisci face the image plane with their concave surfaces. The following conditions are met: ϕ₁:ϕ₂:ϕ₃:ϕ₄=(0,006÷0,1):(1,1÷1,5):-(1,1÷2,7):(1,1÷2,0), where ϕ₁, ϕ₂, ϕ₃, ϕ₄ - the relative optical forces of the first, the second, the third and the fourth menisci, respectively; K1=2,3÷10, K2=0,55÷1,8, where K1, K2 are the asphericity coefficients of the concave surface of the first and the second menisci, respectively.

EFFECT: increasing the field of view, increasing the relative aperture, improving the image quality, simplifying the optical scheme and increasing the transmission coefficient of the lens.

5 dwg, 6 tbl