| 摘要 |
PURPOSE:To prepare a parent material for optical fiber having given transmission properties, preventing cracks during preparation, by blowing a high-temperature gas upon a core part from a nozzle for blowing the high-temperature gas set between a burner for core and a burner for clad. CONSTITUTION:The base material 2 is dropped close to the bottom of the reactor 1. A combustible gas and a raw material gas for forming glass for core are fed to the burner 3 for core, respectively, and the raw material gas for forming glass is hydrolyzed in fire produced by burning the combustible gas. The formed soot 11 for core is attached to the bottom of the base material 2 and gorwn to give the porous preform 12 for core. The preform 12 is pulled up while being rotated, it is heated and shrinked by the jetting gas 13 from the nozzles 4 and 5 for blowing the high-temperature gas, to give the porous preform 14 having the lessened diameter. A combustible gas and a raw material gas for forming glass for clad are then fed to the burner 6 for clad, respectively, the prepared soot 15 is attached to the peripheral surfaces of the perform 12 and 14 to give a clad part, so that the porous preform 16 is obtained. |
