The waveguide (1) has a tubular or hose-like housing (3), where the housing consists of metal. The housing includes an input opening, an output opening, where a centre line (M) extends from the input opening to the output opening. Polished quartz spheres (5) are lined up along the centre line (M), in the interior of the housing (3), where the spheres are made of polished quartz. The light is guided on account of the refraction of a light beam upon entering and exiting from the transparent spheres.