In the region of a distal end at its circumference the waveguide is formed transparent to the radiation which impinges onto the surface of the waveguide at suitable angles, and in the region of the distal end in the inside of the waveguide there are arranged scatter elements which scatter radiation transmitted by the waveguide in the direction of the distal end in a direction with a proximally directed component which exits the circumference of the waveguide. Alternatively, radiation entering into the waveguide at the circumference of the waveguide in a direction with a distally directed component is transmitted by the waveguide in the direction of the proximal end, as well as to its use and to a method for its manufacture.