PRODUCTION OF PREFORM FOR OPTICAL FIBER

摘要

PURPOSE:To obtain preform for optical fiber as an excellent sintered material free from cracking by separating a stream of nonadherent particles along the surface of porous preform synthesized by a specific state and depositing glass fine particles in the axial direction of starting raw material. CONSTITUTION:Glass raw materials containing at least SiCl4 and GeCl4 and a combustion gas are mixed, burnt by a burner and glass fine particles are deposited in the axial direction of a starting raw material or core rod to synthesize porous preform. Then the porous perform is sintered and made transparent to produce preform for optical fiber. In the production, the following treatment is carried out. Namely, an inert gas is sprayed upon the porous preform from the opposite side of the burner based on the central axis of the porous preform. By the spraying, a stream of nonadhering or nondepositing particles are separated from the porous preform and the glass fine particles are deposited to give the aimed preform.