| 摘要 |
An optical element comprises zones of different refraction power or curvature in order to achieve a desired pattern of brightness distribution. In Particular, a darker spot in a central illumination region of an illuminating arrangement including a cold light reflector lamp the light of which is supplied over a fiber optic light guide should be avoided. The optical element has a rotational symmetric annular zone of low or no curvature the outer ring diameter of which being larger and the inner ring diameter being smaller than the diameter of the light exit surface of the fiber optic light guide. A second rotational symmetric zone has a stronger curvature than the first zone. This second zone is situated within the inner ring diameter of the first zone. Both zones face the light exit surface of the light guide. A third zone has a curvature different to the curvatures of the first and second zones, and is situated at the light exit side of the optical element. This third zone is opposite both to the second zone in a rotational symmetric manner and, at least in part, to the first zone in radial relationship.
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