DEVICE AND METHOD FOR FORMING OPTICAL-FIBER PREFORM BY COMBUSTION-LESS HYDROLYSIS

摘要

PROBLEM TO BE SOLVED: To prevent the deposition of a glass grain on the wall of a reaction chamber and to improve a heat-transmission effect by producing a temp. gradient in the reaction chamber and increasing the temp. gradient from an inlet zone to an outlet. SOLUTION: A reaction chamber 14 is demarcated by the tapering side walls 14a and 14b and the end wall. The distance (d) between a vapor outlet 27 of the reaction chamber 14 and a target 26 is controlled to 10-100 mm which is sufficient for the glass grain from a glass aerosol to deposit on the target 26. The reactants transported from pipes 35a and 35b are respectively supplied to an injection chamber. The reactant before being injected is held in a vessel 36 appropriately heated by an electric resistor 37. The temp. difference of at least 100 deg.C is produced between the inlet of the reaction chamber 14 and the outlet zone to prevent the deposition of the grain on the wall of the reaction chamber 14. The reactant is preferably supplied to the reaction chamber 14 at about 700-750 deg.C, and the reactant is set at about 1000 deg.C at the outlet of the reaction chamber 14 to produce a temp. gradient.