| 摘要 |
PROBLEM TO BE SOLVED: To facilitate production by eliminating the inconvenience in a process for production of a preform for an optical fiber. SOLUTION: A jacket tube 1 is held by a chuck 6b and auxiliary pipes 5, 6 are connected to respective ends. A VAD rod 2 connected with an auxiliary bar 4 is inserted into the jacket tube and an auxiliary rod 3 formed with through-holes 3a, 3a is connected to the top end thereof. The VAD rod is held by chucks 6a, 6c in the parts of the auxiliary bar and the auxiliary rod. The openings of the auxiliary pipes are closed. While the inside of a hermetic space 8 is maintained at a reduced pressure state through the through-holes by force suction from the opening of the auxiliary rod, the jacket tube and the VAD rod are successively heated from the lower side to the upper side and are successively integrated by welding both ends. Since the VAD rod is supported at both ends, the VAD rod may be easily and accurately positioned to the same axis as the axis of the jacket tube. The production is facilitated by eliminating the inconvenience in the process for production of the preform for the optical fiber. |
