Optical fibre drawing from preform - involves fibre cooling, with gas stream controlled by gas pressure cushion

摘要

In optical fibre drawing from a solid preform, in which the drawn fibre is cooled from the drawing temp. by a gas stream in a direction opposite the drawing direction, the cooling gas velocity is controlled by an additional gas cushion which pref. opposes the motion of the cooling gas. Appts. for carrying out the process includes a double-walled water-cooled tube (1) with iris diaphragms (7,15) for top and bottom confinement of the fibre passage space, a gas inlet (11) for the pressure cushion being provided at the fibre inlet end of the tube. ADVANTAGE - The fibre is cooled in an almost stationary cooling gas column, so that fibre vibration is avoided and gas consumption is reduced even at high fibre prodn. speeds.