| 摘要 |
PROBLEM TO BE SOLVED: To shorten the initial soot buildup time in a soot formation stage of the production. SOLUTION: This production comprises a stage for forming soot by using a starting member 10 that is provided with a smaller diameter section in the lower part and has a hollow structure, so that the soot diameter (d1 ) in an equilibrium state, the core diameter (d2 ) in an equilibrium state, the diameter (da ) of the smaller diameter section of the starting member 10 and the diameter (dc ) of the starting member 10 on the upper side of a glass fine particle deposition section meet the relational expressions, da <d1 and dc >=d2 . At this time, the soot formation is desirably started in such a state that the temp. of the starting member on the upper side of the glass fine particle deposition section is >=400 deg.C. |
