| 摘要 |
PURPOSE: Provided is a rod in tube(RIT) process for removing moisture in the gap between quartz tube and primary preform by heating under vacuum in manufacturing of optical fiber preforms. CONSTITUTION: The RIT process comprises the steps of: (i) preparing a primary optical fiber preform(10) and a quartz tube(12) with a diameter larger than outer diameter of the primary preform; (ii) inserting the primary preform into the hollow quartz tube and melting the end of the tube with a torch(15); (iii) applying negative pressure to be less than 1atm of pressure between primary preform and quartz tube with a vacuum generator(14) for joining the melted end of the tube and the primary tube and preferably rotating primary preform and quartz tube in a rate of 60rpm or less to improve alignment of primary preform and quartz tube; (iv) moving the torch up and down along the quartz tube over 10min under negative pressure for vaporizing moisture between primary preform and quartz tube, wherein the temperature of the torch is under 2000deg.C and the moving rate is 10mm/min to prevent cracking of quartz tube; (v) moving the torch up and down along the tube for shrinking the tube thermally and fusing quartz tube to primary preform. |
