FAST INFRARED LENS Russian patent published in 2020 - IPC G02B13/14 G02B9/50 

FIELD: optics.

SUBSTANCE: fast infrared lens comprises four components, of which the first and fourth are positive meniscies whose concave surfaces face the image plane are made of germanium, second component is a negative meniscus whose concave surface faces the image plane, is made from zinc selenide, the third component is a negative plane-concave lens which faces the image plane with a flat surface. Third component is made of germanium. First surface of first component is aspherical with conical constant equal to zero, and coefficients of correcting polynomial 2.9871×10^-9, 1.6143×10^-12, -1.7686×10^-17. Relative optical forces of components and air gaps satisfy ratios specified in the claim.

EFFECT: high aperture ratio at high image quality.

1 cl, 4 dwg, 3 tbl