| 摘要 |
In the production of preforms for optical waveguides (optical fibres) by the process, in which a substrate tube is coated on the inside and collapsed, the collapsing operation can be accelerated if a relatively thin substrate tube is used. In order nevertheless to achieve an adequate preform thickness, the invention proposes melting a tube onto the rod produced by collapsing, so that the material of the original substrate tube is thickened. Since silica glass can only be sealed onto silica glass with great difficulty, the interior surface of the tube to be sealed-on is preferably coated with a silica glass material of low softening point. This internal coating can also be supported or replaced by coating the silica glass rod with a silica glass layer of lower softening point before the tube is sealed on. The invention is generally applicable to the sealing of a tube onto a rod in connection with the production of preforms for optical waveguides, irrespective of the process by which the rod is produced. <IMAGE> |
