MELTING FURNACE FOR APPARATUS FOR DRAWING OPTICAL FIBER AND SUPPORTING STRUCTURE FOR BASE MATERIAL FOR OPTICAL FIBER

摘要

An optical fibre spinning furnace (10) has inlet and outlet apertures, a heater (24) for heating an optical fibre preform (12) fed in through the inlet aperture, allowing a bare optical fibre (40) to be drawn out of the outlet aperture, a means for establishing a flow of inert gas (28) from within the furnace out of the inlet aperture, and an inlet sleeve (16) in which the inlet aperture is formed. The inner surface of the inlet sleeve has projections and/or indentations (18) which increase its resistance to flow of the outbound inert gas. Also claimed is a method of connecting an optical fibre preform to an auxiliary quartz rod comprising connecting the preform (12) to an auxiliary quartz rod (44) of smaller diameter, inserting an auxiliary quartz tube (48) over the auxiliary quartz rod (44), and mounting the preform (12) and quartz rod (44) and tube (48) to a chuck of an optical fibre spinning apparatus.