| 摘要 |
PURPOSE:To obtain the titled parent glass material contg. extremely small amt. of impurities, remaining water vapor foams, ununiformity of boundary surface, and chemical defects, etc. in the process for prepg. glass fiber for light transmission by sintering aggregates of fine glass particles by using a specified two stage heating process. CONSTITUTION:Fine glass particles formed by flame hydrolysis are deposited on a revolving glass rod to obtain a desired refractive index distribution forming thus an aggregated body of fine glass particles (circular cylindrical porous parent material for optical fiber). Then, the aggregate of fine glass particles is dehydrated by the primary heating treatment at a temp. range within ca. 950- 1,250 deg.C causing no severe contraction of the fine particles aggregate in an O2 atmosphere contg. chlorine or a chlorine compd. such as CCl4, SOCl2. The material is then heated upto a vitrifying temp., in He atmosphere (pref. contg. <=ca. 50mol% O2), and sintering is executed by maintaining the temp. |
