Process for the production of a glass fiber light waveguide

In a process for the production of glass fiber light waveguides, said process including a chemical vapor deposition process in which a glass layer is formed in a cycle including flowing a gas through a glass tube from one end to the other to deposit a glass forming substance on an inner surface of the tube and subsequently transforming the glass forming substance into a layer of glass, repeating the cycle to obtain the desired number of glass layers, subsequently forming the internally coated glass tube into a rod, and then drawing an optical fiber from an end of said rod, the improvements comprising during each cycle of depositing the glass forming substance and then transforming it into a glass layer, applying a gas pressure to the interior of the tube with the gas pressure being increased relative to the external environment of the tube, wherein the step of transforming the glass forming substance into a glass layer includes rotating the tube, locally heating the tube to create a heating zone to transform the deposit into the glass layer, moving the heating zone along a predetermined path on the tube, and selectively changing at least one of the direction of rotation of the tube and the rotary position of the starting point of the path after each cycle so that the effects of anisotropy of the glass layers is largely eliminated.