FOUR-ELEMENT LENS Russian patent published in 2024 - IPC G02B9/34 

FIELD: optical instrument making.

SUBSTANCE: lens consists of an aperture diaphragm and two two-lens components separated by an air gap. First lens of the objective lens is a negative meniscus whose concave side faces the object, the second is a biconvex lens, the third is a negative meniscus whose concave side faces the image, fourth is convex-flat and faces the image. Lenses inside the first and second components are separated by especially dispersed liquid media (EDLM): in the first component, a medium meeting conditions 1.404≤n_d≤1.417, 53≤v_d≤56, and in the second component—the medium meeting conditions 1.310≤n_d≤1.330, 80≤v_d≤83.

EFFECT: higher orifice ratio and improved manufacturability.

1 cl, 3 dwg