| 摘要 |
PURPOSE:To readily obtain a high-quality porous preform for an optical fiber without adhesion of dust and formation of bubbles, by depositing fine glass particles on the outer peripheral part of a glass rod while taking out the glass rod held in a glass wash liquid therefrom. CONSTITUTION:A glass rod 4 as a starting material is held in a reaction vessel 2 provided with a gas discharge pipe 1, a burner 3 for forming fine glass particles and a wash liquid holding part 7 for holding a glass wash liquid 6, such as dichromate solution acidified with nitric acid, and raw material glass is fed into a flame of the burner 3 to deposit and grow formed fine glass particles on the glass rod 4 which is being rotated. Thereby a porous preform 5 is grown upward. Operation is then performed so that the undeposited part at the bottom of the rod 4 may be always held in the wash liquid 6. The rod 4, as necessary, is taken out of the wash liquid 6 and heated with a drying.vaporizing burner 8 to deposit fine glass particles during deposition thereof to prepare the aimed porous preform for an optical fiber. |
