| 摘要 |
PURPOSE:To obtain the titled base material with superior dimensional accuracy, etc. by introducing oxygen, chlorine or the like into a glass pipe to apply an internal pressure, reducing the pipe in diameter by heat treatment, and depositing a glass film on the inside of the pipe by vapor phase chemical reaction. CONSTITUTION:Glass pipe 1 is attached to glass lathe 2, and after sealing one end of pipe 1, gaseous oxygen, chlorine or hydrogen chloride is introduced into pipe 1 from cylinder 5 through the other end to apply an internal pressure. Pipe 1 is then reduced in outside diameter by heating from one end to the other end with oxyhydrogen burner 3 so that the surface of pipe 1 is adjusted to about 1,800-1,900 deg.C. By changing over change-over valve 4, starting material for a glass film is introduced into pipe 1 from feeder 6 to deposit a glass film on the inside of pipe 1 by vapor phase chemical reaction. Thus, a base material for an optical fiber is obtd. The eccentricity and deformation of pipe 1 are corrected, and the resulting base material has enhanced dimensional accuracy, etc. |
