HIGH-APERTURE LENS FOR INFRARED REGION Russian patent published in 2012 - IPC G02B9/34 G02B13/14 

FIELD: physics.

SUBSTANCE: lens can be used in thermal imaging devices whose receivers are sensitive in the infrared region, particularly in the λ=8-14 mcm region. The lens comprises three meniscus lenses and a further biconvex lens between the first and second meniscus lenses. The first lens is a diverging lens and faces the object with its concave surface. The second and third lenses are converging lenses, face the object with their convex surfaces and are spaced apart by an air space, the value of which is not less than 0.8 times the equivalent focal distance of the lens. The lens satisfies the following relationships: 0.3 < |φ₁/φ_eq| < 0.4, 0.3 < φ₂/φ_eq < 0.4, 0.7 < φ₃/φ_eq ^< 0.8, 0.4 < φ₄/φ_eq < 0.5, where φ₁ φ₂, φ₃ denote focal power of the 1^st, 2^nd and 3^rd meniscus lenses, φ₄ is the focal power of the additional biconvex lens and φ_eq is the optical power of the lens.

EFFECT: high aperture ratio while ensuring high quality of the image on the entire field.

1 dwg, 1 app