| 摘要 |
PURPOSE:To obtain the titled fiber having minimum strength and small static fatigue by putting a quatrz glass rod having a predetermined refractive index distribution inthe radius direction into a high silicic acid tube followed by melt spinning. CONSTITUTION:Preform 11 having a predetermined refractive index distribution in the radus direction and consisting of core and clad is put into high silicic acid glass tube 12 and kept at a suitable temp. with heaters 14a, 14a' while evacuating gap 13. Fiber 15 is then manufactured by melt spinning. Glass tube 12 is obtd. as follow: a phase separated glass tube of Na2O-B2O3-SiO2 or other type is formed by a pulling method or a lowering method, or a glass layer is laminated on a refractory mandrel of carbon ot the like, and the mandrel is drawn out to form a tube, which is then subjected to phase separation heat treatment, leached with a hot acid soln., and washed. The resulting SiO2 porous glass contg. a little B2O3 is dried and heat solidified to collapse micropores, giving a transparent glass tube. |
