| 摘要 |
PURPOSE:To obtain the titled rod suitable for the manufacture of an optical fiber having low light transmission loss, by carrying out the dehydration treatment of a porous preform while increasing the temperature stepwise and decreasing the flow rate of chlorine gas in He atmosphere according to the temperature increase. CONSTITUTION:A raw material gas of glass is supplied to an oxyhydrogen burner and hydrolyzed, and the synthesized soot is deposited at the tip of the rotating target quartz rod 1. A porous preform is grown along the axial direction of the quartz rod 1 to obtain a porous preform 2. He gas and chlorine gas are introduced into the electrical furnace 3 surrounding the preform 2, which is dehydrated by rotating the quartz rod 1. In the above dehydration treatment, the treating temperature is raised stepwise, and the flow rate of the chlorine gas in He gas atmosphere is decreased according to the temperature increase. |
