| 摘要 |
PURPOSE:To produce a preform for optical fiber, capable of providing a preform for optical fiber having no separation of core material from a molded article formed on the outside of the core material, no cracking, no fragment, no crack, etc., and low content of impurities. CONSTITUTION:A production of a preform for optical fiber comprises a process for fitting a core material composed of a quartz-based material to a mold and packing quartz-based powder to the mold, a process for molding the quartz- based powder under pressure to give a porous preform and a process for purifying and transparently vitrifying the porous preform to give a preform for optical fiber. In the operation, quartz-based powder having an average particle diameter smaller than that of quartz-based powder used in the region except the region including both the ends of the porous preform is used as the quartz-based powder used in a region including both the ends of the porous preform. |
