HIGH-APERTURE WIDE-ANGLE LENS FOR INFRARED SPECTRUM (VERSIONS) Russian patent published in 2010 - IPC G02B9/60 G02B13/14 

FIELD: physics.

SUBSTANCE: objective has a first negative meniscus whose convex surface faces the object space, a second positive lens, a third negative meniscus whose concave surfaces faces the object space, a fourth positive lens and a fifth positive meniscus whose concave surface faces the image plane, and an aperture diaphragm. In the first version the aperture diaphragm lies between the fifth meniscus and the image plane, the second lens is a meniscus whose concave surface faces the image plane, and the fourth lens is biconvex. The lenses have relative optical power of (0.20-0.26), (0.16-0.26), -(0.12-0.15), (0.12-0.15), (0.15-0.20) respectively. The distance between the first and second lenses is not greater than 12 times the focal distance of the objective. In the second version the aperture diaphragm lies between the second and third lenses, the second lens is biconvex and the fourth is a meniscus whose convex surface faces the fifth lens. The lenses have relative optical power of -(0.24-0.28), (0.24-0.28), -(0.12-0.15), (0.12-0.15), (0.15-0.20) respectively. The distance between the first and second lenses is not greater than 9 times the focal distance of the objective.

EFFECT: increased image scale, reduced size and mass with retention of the aperture ratio and high image quality.

2 cl, 4 dwg, 2 tbl