OBJECTIVE WITH FOCUS DISTANCE CHANGING IN DISCRETE WAY Russian patent published in 2002 - IPC

FIELD: optical engineering. SUBSTANCE: device has three parts. The first part is fixed. It has positive meniscus turned towards the object with its convex side. The second and the third parts are mounted to enable one to make input into and output from optical system so that only one of them is present in the system. The second part has negative and positive meniscus turned towards the object with its convex side. The third part has three lenses the first of which is flatoconcave and turned towards the object with its concave side, the second one being flatoconvex and turned towards the image with its convex side and the third one being positive meniscus turned towards the object with its convex side. EFFECT: high quality of image in wide vision fields and with spectrum bandwidth being from 8 to 12.5 mcm. 1 dwg