PRODUCTION OF OPTICAL FIBER PREFORM AND APPARATUS THEREFOR

摘要

PURPOSE:To produce an optical fiber preform having high quality easily at a high speed, by forming a porous glass layer on the sidewall of a rotating glass rod using flame hydrolysis process and converting the porous layer to transparent glass layer by heating at a high temperature. CONSTITUTION:A glass rod 2 is supported and rotated by a supporting and rotating device 1. A porous glass layer 3 is formed on the sidewall of the glass rod 2 using a flame stream 7 containing glass soot and ejected from a moving synthesis torch 4. The porous glass layer 3 is heated and sintered at about 1,500-1,600 deg.C with a synthesis torch 5 following the motion of the first synthesis torch 1 to obtain a transparent glass layer 6. The synthesis torches 4, 5 are furnished with flame gas and glass raw material gas from a feeder 10. The diameter of the formed transparent glass layer 6 is measured by a diameter gauge 9 using a laser beam and compared with a prescribed diameter by a comparator 13. The feeding rate of glass raw material of the feeder 10 is controlled by the comparison result to attain a preform having prescribed diameter. An optical fiber preform having high dimensional accuracy can be produced in high reproducibility by this process.