| 摘要 |
PURPOSE:To decrease the cracks by a temp. difference and to obtain a base material of a large size by shortening the deposition length of fine glass particle layers successively from the inner to the outer side at the time of forming the fine glass particle layers on a transparent glass rod. CONSTITUTION:The fine glass particle layers are formed on the rod for a transparent core consisting of GeO2-doped silica, etc., by moving an oxyhydrogen burner to which SiCl4, etc., are supplied back and forth in the axial direction of the rod while the rod is kept rotated. The deposition length of the fine glass particle layers is shortened by the prescribed length at both ends each time when the thickness of the deposited fine glass particle layers attains a prescribed thickness. This rod is then put into a furnace and is vitrified to transparent glass. Formation of the fresh fine glass particle layer on the fine glass particle layers at both ends which are cool is obviated according to this method and, therefore, the failure of the fine glass particle layers occurring in the temp. difference between both is prevented. |
