WIDE-APERTURE LENS Russian patent published in 2004 - IPC

FIELD: optical objectives.

SUBSTANCE: wide-aperture lens includes five lens. First and third lens are positive ones; second and fifth lens are plano-concave negative ones with concavity turned to object; fourth lens is convex-plain one, it has convexity turned to object and thickness consisting 0.4 -0.6 of focal distance of lens. Fifth lens is mounted with possibility of motion along axis and its optical intensity consists 0.6 - 0.4 of that of lens. Invention provides compensation of astigmatism and of image curvature.

EFFECT: compensation of fluctuation of focal length of lens from nominal value due to enlarged technological admissions for lens thickness, for air gaps and dispersion of glasses.

1 dwg