NEAR-IR SPECTRUM LENS Russian patent published in 2019 - IPC G02B13/14 G02B9/12 G02B11/16 

FIELD: instrument engineering.

SUBSTANCE: lens can be used in observation instruments and television viewing systems. Lens for near infrared spectrum includes an aperture diaphragm and three components. First component is a positive meniscus whose convex surface faces the object and is glued from a biconvex lens and a biconcave lens. Second component is a positive meniscus whose convex surface faces the object and is glued from a biconvex and biconcave lens. Third component is a negative meniscus whose convex surface faces the image and is made of glass with a low dispersion index and a low value of the refractive index temperature coefficient. Following conditions are met: F₁/F₂=1.0÷5.0; F₂/F₀=0.6÷1.8; F₃/|F₀|=0.7÷1.4; L₂₃/F₀=0.2÷0.5; where F₁, F₂, F₃, F₀ – focal distances of first, second, third components and lens, respectively; L₂₃ is distance between second and third components.

EFFECT: reduced length of the lens and high image quality in a wide range of temperature variation.

3 cl, 4 dwg, 3 tbl