PROJECTION LARGE-APERTURE LENS Russian patent published in 2011 - IPC G02B9/64 G02B13/24 

FIELD: physics.

SUBSTANCE: projection large-aperture lens comprises fourteen lenses and an aperture diaphragm lying between the fifth and sixth lenses. The first lens is a negative meniscus whose concave side faces the image. The second lens is a negative meniscus whose concave side faces the object. The third, fourth, seventh, ninth and eleventh lenses are biconvex. The fifth, sixth and twelfth lenses are biconcave. The eighth lens is a positive meniscus whose concave side faces the object. The tenth lens is a positive meniscus whose concave side faces the image. The fourteenth lens is a negative meniscus whose concave side faces the object, and its convex surface is non-spherical. The fourth and fifth lenses, the sixth and seventh lenses, as well as the eleventh and twelfth lenses are glued together.

EFFECT: high illuminance on the edge of the image field relative the centre, high aperture ratio, reduced distortion at the edge of the field of vision, increase in the modulus of the linear magnification coefficient.

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