JPH0425215B

1. A method of manufacturing optical fibres, in which glass layers are deposited on the inner wall of a glass tube heated at a temperature between 1 100 and 1 300 degrees C, by passing a reactive gas mixture through the glass tube at a pressure between 1 and 30 mbar, while a plasma is reciprocated strokewise in the interior of the glass tube, after which the glass tube, after a sufficient number of glass layers has been deposited, is collapsed so as to form a solid preform from which optical fibres are drawn, characterized in that the heated glass tube is continuously rotated during the deposition of the glass layers, the direction of rotation being reversed every time the direction of movement of the plasma is reversed, and in that at each reversal of the direction of rotation the glass tube is first rotated through an angle smaller than or equal to 180 degrees around its longitudinal axis before the rotation and the movement of the plasma start again, the angle being selected such that imperfections caused by an asymmetrical energy distribution in the plasma are compensated.