| 摘要 |
PURPOSE:To manufacture a preform for an elliptic core optical fiber by periodically changing the distance between a heating source and a tube as a starting base material in a method of manufacturing a preform for an optical fiber by utilizing a vapor phase chemical reaction. CONSTITUTION:Tube 10 such as quartz tube or Vycor tube as a starting base material is set to glass lathe 11 and rotated at a fixed speed. While heating the whole tube with heating source 12, starting material gases such as SiCl4 and GeCl4 mixed with a carrier gas such as O2 are introduced into tube 10 to deposit additive- contg. sootlike quartz on the inner wall of tube 10. At this time, source 12 is moved from side to side in the arrow 13 direction (the longitudinal direction of tube 10) and vertically moved in the arrow 14 direction (the diametrical direction of tube 10) to form glass film 15 consisting of a thick-walled part and a thin-walled part on the inside of tube 10. Thus 10 is then evacuated, softened by raising the temp., and collapsed to remove the hollow. Thus, a perform having an elliptic core part is obtd. |
