PREPARATION OF OPTICAL FIBER

摘要

A glass body prodn. process comprises: (a) depositing glass soot by flame hydrolysis on a substrate to form a glass soot boule; (b) partially sintering the boule in a helium atmos. in a furnace; and (c) completing sintering of the boule to obtain a glass preform and annealing the preform, both operations being carried out in the furnace in an atmos. which is free of externally applied helium and which comprises an inert gas (pref. nitrogen) that is heavier than helium. Also claimed is optical fibre mfr. involving the above process.