Method of making a tubular member for optical fiber production using plasma outside vapor deposition

摘要

Tubular members suitable for optical fibre preforms are made by providing a high frequency plasma source 40 including a coil moveably positioned along the length of the target substrate 30 and spaced 30-55mm therefrom, introducing a plasma gas eg air with a hydroxyl content of less than 2 ppm along line 42 to form a plasma, introducing a source gas comprising SiCl4 having a hydroxyl content of less than 0.5 ppm along line 44 into the region of the plasma and depositing a reaction product of the gases on to the target to form a tubular member 34 whilst maintaining the spacing between the target and the coil.