| 摘要 |
PROBLEM TO BE SOLVED: To provide a reliable glass base material for an optical fiber by preventing interface staining between a core rod and a glass tube, avoiding intrusion of an OH group and efficiently carrying out collapse. SOLUTION: In the method for manufacturing the glass parent material, a glass tube 31 with a core rod 32 inserted inside is inserted in a heating furnace 33 provided with a heating means, the pressure in the heating furnace is maintained to the level of a first pressure which is positive pressure while the pressure in the glass tube is maintained to the level of a second pressure which is in the range of the first pressure and the atmospheric pressure, and the glass tube 31 is gradually heated from one end so that the core rod 32 and the glass tube 31 are welded. COPYRIGHT: (C)2003,JPO
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