| 摘要 |
In the manufacture of an optical cable element comprising a tube of plastics material loosely housing at least one optical fibre, a water-impermeable medium in a liquid or semi-liquid state is applied to an advancing optical fibre immediately upstream of an extruder in such a way and under such a pressure that the advancing optical fibre with water-impermeable medium therearound passes into the extruder. After a tube of polymeric material has been extruded around the advancing optical fibre and the surrounding water-impermeable medium in such a way that the internal diameter of the tube is greater than the overall diameter of the optical fibre and the extruded tube has been drawn down and so treated that the molecules are longitudinally oriented, the space in the tube not occupied by the optical fibre is filled with water-impermeable medium of a jelly-like nature.
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