| 摘要 |
<p>PURPOSE:To obtain an optical fiber low in transmission loss by specifying the temp. drop of an optical fiber from a neck-down part and the time required to cool the optical fiber and then coating the fiber with resin. CONSTITUTION:An optical fiber preform 1 is inserted into a drawing furnace 4 provided with a furnace core tube 10, a heater 2 and an insulating mateial 3, and the tip of the preform is heated above the softening point. The heated and softened optical fiber leaving the drawing furnace is passed through a protective tube 11, the outer diameter is monitored by a measuring device 5, then the optical fiber is coated with a resin by a die 6, the resin is cured by a resin curing furnace 7, and the optical fiber is wound on a bobbin by a winder 8. In this process, the optical fiber from a neck-down part 20 is cooled to 600 deg.C in 0.25 to 0.5sec by appropriately adjusting the length of the protective tube 11, and the optical fiber is cooled by a forced cooler and coated with the resin.</p> |
