VARIABLE FIELD OF VIEW HIGH-APERTURE LENS FOR THERMAL IMAGER (VERSIONS) Russian patent published in 2015 - IPC G02B9/62 G02B15/14 G02B13/14 

FIELD: physics.

SUBSTANCE: lens according to both versions comprises four components, the second and fourth of which are fixed and have two fixed positions each. The first component is in the form of a positive meniscus whose concave surface faces the image plane, the third component is in the form of a positive meniscus whose convex surface faces the image plane, and the fourth component is positive and is in the form of two menisci whose convex surfaces face each other. In the first version, the second component includes a biconcave lens and a negative meniscus facing the biconcave lens with its convex surface. In the second version, the second component is in the form of two negative menisci facing each other with their concave surfaces. Relationships given in the claim are satisfied.

EFFECT: wider angular field, high aperture ratio in narrow field of view mode, providing quasi-equal aperture ratio values when changing the field of view, short relative length of the lens while providing high image quality.

5 cl, 12 dwg, 2 tbl