| 摘要 |
PURPOSE:To suppress secondary pollution by water and produce optical fiber having high strength by making possible to successively perform surface treatment and drawing of preform for fluoride optical fiber with installing fluorine gas supplying chamber in upper part, and discharging chamber and inert gas supplying chamber in lower part of a furnace core tube. CONSTITUTION:Preform 13 for fluoride optical fiber is set in a furnace core tube 12 drawn with heating and softening by a heater element 11 to form fluoride optical fiber 14. In said process, F2/Ar mixed gas is introduced from gas introducing tube 21 into gas suppling chamber 17 installed in upper part of the furnace core tube 12 and simultaneously dried N2 gas is introduced into inert gas supplying chambers installed in lower part of the furnace core tube 12, connected in series with shutters 24 and communicated through fiber drawing holes 24a, then gas introduced to inside of the inert gas supplying chamber is discharged through upper discharging chamber 25 to isolate atmosphere in the furnace core tube from outside air and subject the preform 13 to OH- removing treatment, thus the preform is drawn. |
