| 摘要 |
PROBLEM TO BE SOLVED: To produce a preform for an optical fiber having stable characteristics while preventing the characteristics from being changed at the intermediate treatment steps of its production process. SOLUTION: The preform for an optical fiber is produced by spraying the raw material of the optical fiber containing a dopant onto a starting base material S from a burner 2 for a core to accumulate a core base material in the axial direction, spraying another raw material of the optical fiber from a burner 3 for a clad to accumulate a clad base material and then dehydrating and sintering. The production repeating this procedure is carried out by measuring the distribution of the refractive indexes of the core base material of the base material produced with a preform analyzer 7, calculating the difference between the difference of the measured refractive indexes and the target difference of the refractive indexes using a sequencer 6, converting this difference into a correction value of the dopant supply amount and correcting the amount to be supplied to the dopant on the basis of the correction value through a regulator 5. |
