Outside diameter controlling method of optical fiber base material

Abstract

Abstract PURPOSE:To obtain an optical fiber base material of a uniform outside diameter by detecting the outside diameter during the deposition process near the end face of growth optically noncontactually and controlling the axial moving speed of the porous base material based on the detection signal thereof in such a manner that the outside diameter becomes constant. CONSTITUTION:In the production of an optical fiber base material by depositing fine glass particles at the tip of a bar-shaped starting material, allowing the bar- shaped fine glass particle deposited body to grow and converting this to transparent glass in a heating furnace, the part A-A' of the deposit is placed in the laser luminous flux 14 which repeats scanning at fixed speed by a laser scanning part 9. The length of the shadow produced thereby is received in a photodetecting part and is electrically processed to a detection signal. This detection signal and the signal corresponding to the present reference outside diameter is inputted to a control circuit 11, which so acts that when the detection signal is smaller than the reference signal the motor drive voltage lowers to decelerate the target 5, thereby approaching the detection signal and the reference signal. If the detection signal is larger than the reference signal, it operates reverse.

Inventors

• 👤 Katsuyuki Imoto
• 👤 Masao Sumi
• 👤 Koji Ishida
• 👤 Yasuo Suganuma

Bibliographic Details