MANUFACTURE OF PREFORM FOR OPTICAL FIBER

• Main Authors: KAMIYA TAMOTSU, TOYODA KUNIHIKO, FURUYA NORIAKI
• Format: Patent
• Language: English
• Published: 01.07.1985
• Subjects: CHEMISTRY; GLASS; MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES; METALLURGY; MINERAL OR SLAG WOOL; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

PURPOSE:To prevent the expanding and bursting of a reaction tube at the position by keeping the internal pressure of the reaction tube in the vicinity of the position on the supply sie of a glass material where the forward trip of a burner is started higher than the external air pressure and lower than the internal pressure of the other part in an internal CVD method. CONSTITUTION:A reaction tube 2 is rotated, and a glass material is supplied from one end. A burner 5 is travelled rightward, and high-pressure air is supplied into a control chamber 3 by a fan 13 to keep the internal pressure of the chamber 3 at P1 which is necessary for keeping the equilibrium with the shrinking force of the reaction tube 2. when the burner 5 reaches the terminal of the forward trip and strikes against a limit switch 6b, the opening degree of a motor valve 14 is decreased and the flow rate of the high-pressure air is reduced to keep the internal pressure of the control chamber 3 at P2 which is lower than the pressure P1 and slightly higher than the external air pressure. The pressure P2 is kept until the burner 5 collides against a limit switch 6a on the other side and changes its direction and a specified time elapses. The pressure P1 is increased to P2 after a specified time.