DOUBLE LENS Russian patent published in 2021 - IPC G02B9/10 G02B13/14 

FIELD: optical systems.

SUBSTANCE: lens can be used both in visual optical systems and in IR systems. The lens consists of two single biconvex lenses and a negative meniscus facing the image with a bulge. The radii of a biconvex lens are equal in absolute magnitude. There are the following ratios: 0.3≤|R₁|/f'≤0.48; 0.25≤|R₃|/f'≤0.45; 1.5≤|R₄|/f'≤7; 0.07≤|R₃|/|R₄|<0.8, where R₁, R₃, R₄ are the radii of the first, third, and fourth optical surfaces in the course of the rays; f' is the focal length of the entire lens.

EFFECT: increase in the focal length, the diameter of the entrance pupil and the angular field in the space of objects with high image quality.

1 cl, 1 dwg, 2 tbl