| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a glass preform minimizing variation of a refractive index profile in the axis direction. SOLUTION: In the method for manufacturing a glass preform according to the present invention, a glass particle deposit 3 is previously formed in the circumference of a core rod 2 so that the outer diameter of the effective part of a porous glass preform G2 gradually increases from the lower end side toward the upper end side by adjusting the flow rate of a raw material gas for a burner 21. The part near the lower end (A-side) which is the part having a smaller outer diameter of the effective part of the porous glass preform G2 is precedently sintered with a heater 4 and then the porous glass preform G2 is sintered from the lower end side toward the upper end side to convert it to a transparent glass. COPYRIGHT: (C)2007,JPO&INPIT
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