LENS WITH DISCRETE CHANGE OF FOCAL LENGTH Russian patent published in 2008 - IPC G02B15/02 

FIELD: physics.

SUBSTANCE: lens has three focal lengths and contains four components. The first, second and fourth components are positive, while the third one is negative. The second component together with the fourth one provide possibility of data input and output from optical system and are designed different for two focal lengths. The first component consists of biconvex and biconcave lenses glued to each other, and positive lens made of glued positive and negative meniscus elements with their convex surfaces facing toward the object side. The second component comprises single biconcave lens and positive single meniscus element with its convex surface facing toward the object side. The third component consists of mutually glued negative meniscus element, its concave surface facing toward the object side, and the positive meniscus element? Its concave surface facing toward the object side. The fourth component includes mutually glued biconvex lens and negative meniscus element with its concave surface facing toward the object side, and positive lens made of mutually glued biconvex and biconcave lenses.

EFFECT: increased linear field of view and relative aperture.

2 cl, 2 dwg