Patent ID: 8904827

Claim:
A method for manufacturing an optical preform via an internal vapor deposition process, wherein use is made of a reaction zone and a quartz glass substrate tube having a supply side and a discharge side, wherein the reaction zone is movable over the length of the substrate tube between a supply-side point of reversal and a discharge-side point of reversal, the method comprising the steps of: continuously supplying one or more glass-forming precursors by the internal vapor deposition process to the interior of the substrate tube at the supply side of the substrate tube such that deposition of glass layers continuously takes place on the interior of the substrate tube and components that have not been deposited on the interior of the substrate tube are discharged at the discharge side of the substrate tube, and setting a velocity of the reaction zone during the inside deposition process so that the velocity of the reaction zone over the length of the supply side-to-discharge side is higher than the velocity of the reaction zone over the length of the discharge side-to-supply side.