IR OBJECTIVE WITH SMOOTHLY CHANGING FOCAL LENGTH Russian patent published in 2007 - IPC G02B13/14 G02B15/16 

FIELD: optical engineering.

SUBSTANCE: objective with smoothly changing focal length has motionless first component, having positive concave-convex lens being capable of movement along optical axis, disposed in series with movable second component supplied with negative concave-convex lens, and third component made in form of negative concave-convex lens, motionless fourth component made in form of positive concave-convex lens, and fifth component having first and second positive concave-convex positive lenses. First component additionally has negative concave-convex lens, third negative biconcave, fourth positive biconvex and fifth positive convex-concave lenses. Second surface of first lens of fifth component is made aspheric.

EFFECT: increased time of change in focal length; reduced length of objective; improved quality of image.

3 cl, 1 dwg