Fremgangsmåde til udførelse af en PCVD-pådampningsproces

摘要

A method for carrying out a PCVD deposition process, said method comprising the steps of : i) providing a glass substrate tube; ii) supplying one or more glass-forming gasses to the substrate tube of step i); iii) inducing a plasma by means of microwave radiation on at least a part of the substrate tube of step ii) to induce deposition of one or more glass layers onto the interior surface of the substrate tube; wherein at least one plasma-reactive gas is supplied to the substrate tube during step iii) in one or more pulses as a function of the axial position of the plasma along the length of the substrate tube, characterized in that one single pulse is supplied of plasma-reactive gas and wherein the length and position of said pulse is selected to fall in a longitudinal position corresponding to a deposition oscillation, said deposition oscillation being a variation in the thickness or composition of the deposited glass over the length of the substrate tube.