INFRARED LENS WITH SMOOTHLY VARIABLE FOCAL DISTANCE Russian patent published in 2015 - IPC G02B13/14 G02B15/16 G02B9/64 

FIELD: physics.

SUBSTANCE: lens comprises, arranged in series along an optical axis, a fixed first component consisting of a positive convex-concave lens, mobile second component, consisting of a first negative convex-concave and a second biconcave lens, and third component comprising a biconvex lens, configured to move along the optical axis, and fixed fourth component, comprising a negative concave-convex lens and an additional positive concave-convex lens, and fifth component consisting of a first negative concave-convex and a second biconvex lens. An intermediate image is formed between the fixed fourth and fifth components. An aperture diaphragm is situated between the fifth component and the image plane.

EFFECT: high smooth zoom ratio with reduced displacement of movable components and remote shrinking coefficient and offset of the aperture diaphragm in the space between the lens and the image plane.

2 dwg, 3 tbl