APPARATUS FOR PREPARING PARENT MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:To control inside pressure of a reaction tube precisely with good response by feeding back the directly measured inside pressure of the reaction tube to a blower and to control the pressure of introduced gas. CONSTITUTION:An accumulated glass layer is formed in a reaction tube 1 heated by a heater 4 setting simultaneously the pressure inside of the reaction tube by 10mm H2O column higher than the external pressure by a setter 13. The set value is inputted together with measured value of a pressure measuring device 7 to an operator 12. The number of revolution of the blower 10 is controlled through a driving part 11 so as to be in direct proportion to the pressure difference between the set value of the setter 13 and the measured value of the measuring device 7, thus controlling the pressure of introduced gas introduced from a gas introducing port 8. By this method, a parent material for optical fiber having no fluctuation of outside diameter is obtd.