An ultraviolet radiation curing system is disclosed for treating a substrate, such as fiber optic cable or silicone tubing. The system comprises a processing chamber allowing transport of a continuous piece of substrate to be treated. As the substrate moves through the processing chamber, ultraviolet radiation from a plasma lamp activated by a microwave generator treats the surface of the substrate. The system comprises two elliptical reflectors of different sizes so that larger diameter substrates may be efficiently treated with ultraviolet radiation. The system may also comprise an ultraviolet-transmissive conduit enclosing the substrate and split into a first portion and a second portion, where the second portion is movable from the first portion to open the conduit and allow insertion or alignment of the substrate within the conduit and processing chamber.