HIGH-SPEED THREE-LENS OBJECTIVE FOR IR SPECTRUM Russian patent published in 2017 - IPC G02B13/14 G02B9/16 G02B13/18 

FIELD: physics.

SUBSTANCE: lens can be used in thermal imagers with matrix photosensitive cells sensitive to the spectral range from 8 to 12 mcm. The lens contains three meniscuses. The first and third meniscuses-positive face concave surfaces to the plane of the image and made of germanium. The concave surfaces of the meniscuses are conical: the conic constant of the first meniscus is from 1 to 2.4, and the third meniscus is from (-1.9) to (-5.9). The second negative meniscus is concave surface to the plane of the image and made of material with a refractive index from 2.2 to 2.8. Operating the equations: ϕ₁=(0,71÷0,8)ϕ, ϕ₂=-(0,46÷1,17)ϕ, ϕ₃=(1,63÷2,16)ϕ, where ϕ₁, ϕ₂, ϕ₃ - relative optical force of the first, second, third meniscuses; ϕ -the optical power of the lens; D2/L=0,21÷0,41; D4/L=0,15÷0,36 where D2, D4 - Air gaps between first and second and the second and third meniscuses; L is the length of the lens.

EFFECT: improvement of image quality and reduced length of the lens.

4 cl, 11 dwg