OPTICAL FIBER DRAWING FURNACE AND DRAWING METHOD

摘要

PURPOSE:To provide the optical fiber drawing furnace and drawing method capable of decreasing the fluctuations in the outside diameter of an optical fiber at the time of drawing. CONSTITUTION:This optical fiber drawing furnace is constituted to introduce an inert gas 17 into a furnace core tube 103 and to draw an optical fiber preform 12 inserted into this furnace core tube 103 by heating and melting this preform. This furnace core tube 103 consists of a cylindrical furnace core tube 101 and a funnel-shaped furnace core tube 102 which is disposed while having a spacing S2 on the inner side in the lower part of this cylindrical furnace core tube 101 and has a shape complying with the drawing shape of the optical fiber preform 12. The aperture in the upper part of the funnel-shaped furnace core tube 102 and the inside of the cylindrical furnace core tube 101 are communicated with each other.