| 摘要 |
PURPOSE:To obtain a base material for an optical fiber having a uniform ratio between the core diameter and the outside diameter by placing a means of decreasing the flow speed of gaseous starting material in the vicinity of the gaseous starting material inlet of a glass tube so as to form a glass-deposited film having a uniform thickness. CONSTITUTION:The gaseous starting material introducing end 22 of a glass tube 21 attached to a glass lathe 23 is rotatably seal-connected to a gaseous starting material feeding pipe 26 through a connecting member 29 and a decelerator 27 having semicircular through holes 28. Gaseous starting material from the pipe 26 is fed into the tube 21 through the holes 28 of the decelerator 27 like arrows 30 to decrease the flow speed, and it is allowed to flow through the tube 21 in the longitudinal direction as a turbulent flow at a low flow speed. By locally heating the tube 21 with a heating means 24 mounted on a moving stand 25, a vapor phase chemical reaction is caused to deposit a glass film on the inner wall of the tube 1. |
