| 摘要 |
PURPOSE:To obtain a high-quality single-mode optical fiber not contg. any bubble and with its axial center aligned with that of a core. CONSTITUTION:A preform 1 having a preform clad part 1B on the outer periphery of a preform core part 1A and consisting of a quartz column, a covering tube 30 consisting of a quartz tube having the hollow hole into which the preform 1 with the upper part held and hung with a covering tube chuck 17 is loosely inserted and having an inner diameter larger than the outer diameter of the preform 1 by >=1mm and a dummy rod 20-1 with the lower end face connected to the upper end face of the preform 1 so that both axial centers are aligned and consisting of a quartz column with the upper part held by a chuck 16 and suspended in the covering tube 30 are used. A means for aligning the axial center of the rod 20-1 with that of the covering tube 30 and a means for discharging the air between the preform 1 and covering tube 30 to the outside are formed, the preform is inserted and suspended in the hollow hole of the covering tube 30, the lower parts of the preform 1 and covering tube 30 are heated and softened, and the preform is drawn. |
