Method for the production of a blank mold for optical fibers

2 2 2 2 In a known method for the production of a blank mold for optical fibers, a fluorine-doped SiOenveloping glass is produced on a core glass cylinder that rotates about its longitudinal axis, wherein a silicon-containing starting substance is fed to a plasma burner, said substance is then oxidized in a plasma flame assigned to the plasma burner to obtain SiOparticles, the SiOparticles are deposited by layers on the enveloping surface of the cylinder of the core glass cylinder in the presence of fluorine and sintered into the enveloping glass. The invention aims at providing an economical method, which builds upon the above-mentioned method, in order to produce a blank mold from which optical multi-mode fibers can be obtained. In comparison with fibers produced according to standard methods, said optical multi-mode fibers are characterized by high initial transmission in the UV wavelength range and good resistance with respect to brief UV radiation, more particularly in the 210-300 nm wavelength range. According to the invention, a plasma flame that irradiates an ultraviolet light having a wavelength of 214 nm with an intensity of at least 0.9 ?W-determined on the basis of plasma flame intensity measurement-is used for the formation and deposition of the SiOparticles on the core glass.