Patent ID: 6474109
Filing Date: 2002-11-05
Classification: C03B

Abstract:
A device for drawing optical fibres from a preform, comprising:a furnace comprising a tube for heating one end of said preform to the drawing temperature thereof, which tube comprises: i) a central tube, ii) an upper extension tube connected to the lower part of said central tube so as to obtain a gas tight seal against an ambient atmosphere exterior said furnace, wherein the upper extension tube comprises an inlet for an inert gas in the top region of the upper extension tube, as a result of which the preform and the fibre to be drawn therefrom are surrounded by an inert gas, iii) a lower extension tube connected to said upper extension tube in such a manner that a gas tight seal against an ambient atmosphere exterior said furnace is obtained, iv) a tube outlet connected to said lower extension tube, means for drawing the fibre, means for supporting the preform in the furnace, wherein the tube outlet is conical in shape, wherein the internal diameter of the end of the tube outlet is smaller than the internal diameter of the upper extension tube so as to prevent the ingress of ambient atmosphere and turbulence and swirling within the tube outlet, which tube outlet includes a number of outlet openings for inert gas disposed on the circumference of said conical shape.