VARIABLE FOCAL LENGTH LENS Russian patent published in 2008 - IPC G02B15/16 

FIELD: optical instrument making.

SUBSTANCE: lens incorporates the first and second group of optical elements arranged in the radiation propagation direction along the lens optical axis, an aperture diaphragm, a third, fourth and fifth groups of optical elements, an optical low-frequency filter and an image pickup. The fifth group of optical elements features a positive optical force and contains a positive bi-convex lens and a negative bi-concave lens, both surfaces of which being aspherical. On varying the focal length, the second group of optical elements allows a linear motion along the lens optical axis towards the aperture diaphragm, while the third group allows a non-linear motion along the optical axis for mechanical compensation of the image plane shift. In variation of the focal length from a wide-angle to a long focal length position, the distances between the first and second groups of optical elements get increased.

EFFECT: smaller sizes, greater relative aperture, angle of vision, higher-quality image.

3 cl, 14 dwg