Abstract: An optical system forms an image of a light source, such as a short arc lamp, particularly of a high numerical aperture, via a spherical, concave reflector onto the entrance surface of a light guide. The reflector is asymmetrically arranged to the light source, and the latter has a relative large angular distance from the axis of symmetry of the reflector, so that the light guide in the path of reflected rays has also a large angular distance from this axis of symmetry and, hence, from the hot light source. In the path of rays between the light source and the spherical, concave reflector is a cylindrical lens, preferably a circular cylindrical lens, of positive diffraction.

Abstract: An optical system forms an image of a light source, such as a short arc lamp, particularly of a high numerical aperture, via a spherical, concave reflector onto the entrance surface of a light guide. The reflector is asymmetrically arranged to the light source, and the latter has a relative large angular distance from the axis of symmetry of the reflector, so that the light guide in the path of reflected rays has also a large angular distance from this axis of symmetry and, hence, from the hot light source. In the path of rays between the light source and the spherical, concave reflector is a cylindrical lens, preferably a circular cylindrical lens, of positive diffraction.

Abstract: An attachment lens is provided for an annular fiber optic illumination system which extends along a rotational axis for distributing the intensity of light beams emanating annularly from a light emanating surface of the fiber optic illumination system onto an object to be illuminated. The attachment lens comprises a ring-shaped optical element to be arranged concentrically with respect to the annular light beams and the rotational axis in a desired distance from the light emanating surface of the fiber optic illumination system. The ring-shaped optical element has a first rotationally symmetrical zone of a refractive power which increases towards the rotational axis for the annular light beams emanating from the fiber optic illumination system, and a second zone substantially for light beams which are aligned or parallel to said rotational axis. The second zone is adjacent the first zone and concentric to it and substantially free of any refractive power.

Abstract: 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.