FOUR-ELEMENT LENS Russian patent published in 2012 - IPC G02B9/12 

FIELD: physics.

SUBSTANCE: lens has, on the beam path, a double-lens component glued from a converging-meniscus lens whose convex side faces the object and a divergent-meniscus lens whose concave side faces the image, a single biconcave lens and a single biconvex lens. An aperture diaphragm is located behind the last biconvex lens. Radii of optical surfaces, refraction indices and dispersion coefficients of optical material of the lenses and the focal distance of the lens satisfy the certain relationships given in the claim.

EFFECT: high aperture ratio, larger field angle in the object space and high technological effectiveness.

3 cl, 1 dwg, 2 tbl