OBJECTIVE WITH VARIABLE FOCAL DISTANCE Russian patent published in 2008 - IPC G02B15/16 

FIELD: optics; objectives.

SUBSTANCE: objective consists of four groups of optical elements, an aperture diaphragm, low-pass optical filter and an image detector, all arranged in series along an optical axis. The first, third and fourth groups have positive optical power, and the second group has negative optical power. The aperture diaphragm, third and fourth groups are rigidly joined together and are made with provision for non-linear displacement along the optical axis. The position of the first group, low-pass optical filter and the image sensor remains fixed. The second group is made with provision for linear displacement along the optical axis. The first group consists of serially arranged convex-concave divergent meniscus lens, bi-convex lens with an aspherical surface and convex-concave convergent meniscus lens. The second group consists of convex-concave divergent meniscus lens with an aspherical surface, bi-concave lens and a concave-convex convergent lens with two aspherical surfaces. The third group consists of a bi-convex lens and a concave-convex divergent meniscus lens with an aspherical surface. The fourth group consists of concave-convex divergent meniscus lens and a concave-convex convergent meniscus lens.

EFFECT: making a compact objective, with small dimensions combined with high luminosity, lager field and high quality of image.

5 cl, 7 dwg