LARGE-APERTURE LENS Russian patent published in 2009 - IPC G02B9/34 G02B13/14 

FIELD: physics, optics.

SUBSTANCE: invention concerns lenses operating in long-range infrared range of wavelengths, and can be applied in thermal vision devices. Lens consists of four components, the first one being a single positive meniscus lens with concave side oriented towards image side. Second component is a single negative meniscus lens with convex side oriented towards image. Third and fourth components are single positive meniscus lenses. Third lens is oriented towards image with its convex side. Fourth lens is oriented towards image with its concave side. First and third components are made of germanium. Second and fourth components are made of zinc selenide. All optic surfaces are spherical and meet the requirement: |R₂| = |R₅|; |R₃| = |R₆| = |R₈|; |R₅| > |R₆|, where: R₂, R₃, R₅, R₆, R₈ are radii of second, third, fifth, sixth and eighth optic surfaces respectively.

EFFECT: improved manufacturability, increased focal distance and aperture ratio at high image quality.

1 dwg