WIDE-APERTURE LENS Russian patent published in 2002 - IPC

FIELD: optical engineering. SUBSTANCE: device has two positive parts. The first part has concavo-concave and convexo-convex negative lenses the first of which is convexo-convex one and the second one is negative meniscus turned towards the object with its concave side. Relations are selected between objective focal distances and its parts, thickness values and air gaps. Relative aperture is not less than 1:2, angular vision field is greater than 11 deg and optical system length is less than 1.4 f. EFFECT: high quality of point image on the axis and in field mode. 3 dwg