| 摘要 |
PURPOSE:To improve fatigue resistance and deterioration resistance by heating uncoated fiber prepared by melt spinning of optical fiber preform, passing the uncoated fiber through a reaction furnace into which a specific gas is introduced and coating the surface of the uncoated fiber with pyrolytic carbon by CVD method. CONSTITUTION:An optical fiber preform 1 is subjected to melt spinning by a wire drawing furnace 15 to give uncoated fiber 2 at 700-1,400 deg.C, which is sent to a reaction furnace 16 equipped with branched tubes 6, 7 and 9, a sealing gas such as N2 is fed from the branched tubes 6 and 9, a mixed gas of a hydrocarbon and a chlorine catalyst in ratio of number of molecules of 20-70% is sent from the branched tube 7 and a coating film of pyrolytic carbon is formed by CVD method. Wire drawing rate is controlled so that the outer diameter of coated fiber is measured by a laser device 17 and becomes a given dimension. The fiber having passed the laser device 17 is cooled and coated with a resin by a die 19. |
