INFRARED OBJECTIVE LENS WITH TWO FIELDS OF VISION AND REMOTE APERTURE DIAPHRAGM Russian patent published in 2010 - IPC G02B13/14 G02B15/16 G02B9/64 

FIELD: physics.

SUBSTANCE: objective has fixed positive first and last components between which there is a movable negative meniscus whose convex surface faces the image plane and a positive component. The first component contains a positive and a negative meniscus whose concave side faces the image plane. The last component is in form of two positive menisci whose convex surfaces face each other, and a negative meniscus whose concave side faces the image plane. The movable component includes a divergent and a convergent lens and a negative meniscus whose convex side faces the image plane lying tightly in front of the divergent lens of this component. The aperture diaphragm is placed between the objective lens and the image plane. The entrance pupil is superposed with the first surface of the objective lens.

EFFECT: exclusion of aspherical and diffraction optical elements, reduced diameter of the objective lens and distance from the aperture diaphragm to the image plane with maintenance of high aperture ratio, drop in magnification and image quality.

8 dwg, 1 tbl