| 摘要 |
In the mfr. of a preform from which optical waveguide fibre is drawn is provided. In this method a first soot stream and a second soot stream are separately formed and then directed to and collected on a mandrel. The streams are produced by oxidising separately generated vapour flows at first and second oxidation sites. The flow to the first site contains at least a first precursor (I) and that to the second site contains at least a second precursor (II) but not (I). Also claimed is a method where first and second vapour flows are oxidised into separate first and second soot particle streams. The first vapour flow contains at least (I) and (II). THe second vapour flow contains at least (II) but not (I). Pref. (I) is a cpd, which forms Si02 on oxidn, a metal halide or an organometallic cpd or a combination of precursors for Si02 and Ge02 which combination is formed before delivering the first vapour flow to the oxidn. site. (II) contains precursors for at least one of Ge02, Ti02, rare earth oxide or other meal oxides. (II) is a beta-diketonate complex. |
