| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method of a glass preform capable of preventing heat deformation of a quartz core tube, even in the case where the quartz core tube is not crystallized (devitrified) when dehydrating/sintering the glass preform.SOLUTION: In a production method of a glass preform 12 for making the glass preform 12 transparent by heat treatment after inserting the glass preform 12 into a quartz core tube 2, the first heating temperature at which heat treatment is performed before devitrification of the quartz core tube 2 is set at a lower temperature than the second heating temperature at which heat treatment is performed after the devitrification of the quartz core tube 2. |
