| 摘要 |
PURPOSE:To produce a base material of optical fiber having uniform composition and refractive index by closing an end near an introducing side of a gas of a reaction tube and providing an introducing means for raw material gas held at a retained temp. to near the closed end of the reaction tube. CONSTITUTION:An end of a quartz hollow reaction tube 21 is closed and a supporting bar 21a is attached thereto, which is fitted to a rotating mechanism 2. An introducing port 24 for raw material gas 22 is bored on the side wall of the tube near the closed end of the tube. An annular rotary connector 23 having an introducing port for gas is attached airtightly and freely movable around the outside periphery of the tube 21 to the neighborhood of the board gas inlet port 22. Further, a heat-retaining cover 25 is applied to the reaction tube 21 to the area near said attachment. The raw material gas for forming a glass layer is introduced into the reaction tube through the annular rotary connector 23, and the tube wall is locally heated by moving an oxyhydrogen burner 3. In this stage, there is no fear of causing liquefaction nor stagnation of the raw material gas in any part of the reaction tube except the zone where the deposition of the glass is to be caused. Therefore, a layer 4 of deposited glass having uniorm glass compsn. and refractive index is formed to a specified thickness in the longitudinal direction of the reaction tube 21. |
