OPTICAL SYSTEM FOR THERMAL IMAGING DEVICE HAVING TWO VIEWING FIELDS Russian patent published in 2015 - IPC G02B13/14 G02B15/02 G02B9/64 

FIELD: physics.

SUBSTANCE: optical system consists of three components arranged along an optical axis. The first fixed component comprises a first negative and a second positive convex-concave lens and a negative concave-convex third lens. The second movable component is configured to enter and exit an optical path and comprises first and second negative concave-convex lenses and an additional third biconvex lens. The fixed third component comprises a first positive and a second negative concave-convex lens and a third positive convex-concave lens and a fourth positive concave-convex lens. The movable second component is mounted in the space between the fixed first and third components.

EFFECT: high ratio of variation of the viewing field and remote shrinking coefficient while maintaining image quality.

1 dwg, 3 tbl