| 摘要 |
PROBLEM TO BE SOLVED: To suppress lowly production cost by use of helium gas, in a production method of a glass preform by sintering and transparentizing a porous glass preform.SOLUTION: A production method of a glass preform by sintering and transparentizing a porous glass preform 3 comprising an effective part 3a and an ineffective part 3b includes: a first step for sintering the effective part 3a, while supplying helium (He) gas into a sintering furnace 1; and a second step for sintering the ineffective part 3b, while supplying at least either of nitrogen (N) gas and argon (Ar) gas into the sintering furnace 1. |
