LARGE-APERTURE LENS Russian patent published in 2010 - IPC G02B9/60 

FIELD: physics, optics.

SUBSTANCE: large-aperture lens can be used in night vision devices. The large-aperture lens has a positive and a negative meniscus along the beam path whose convex sides face the object side, an aperture diaphragm, a negative component made from a biconcave and a biconvex lens glued together, a biconvex lens and a positive meniscus whose concave side faces the image. The focal distance of the lens, radii of certain surfaces, thickness of the second meniscus, the Abbe number and refraction indices of the last three elements are related through expressions given in the formula of invention.

EFFECT: increased aperture ratio and viewing angle with good image quality.

1 dwg, 2 tbl