Abstract: The invention relates to an irradiation device which is employed in particular in an arrangement for cladding a filamentary body 5, and to a method of cladding such a filamentary body 5, which irradiation device comprises a light source 1 and at least one optical conductor 4 which is provided with a light-entrance window at a first end and a light-exit window at a second end, the light-entrance window being directed to the light source.A cylinder lens 6 is positioned between each light-exit window and the location of the object to be irradiated during operation of the device.Preferably, the first end of the optical conductor 4 is sealed into the wall of a lamp envelope and the cylinder lenses are provided in the wall of a mainly cylindrical body 7 through which a filamentary body 5 which is to be clad can be led.