| 摘要 |
PROBLEM TO BE SOLVED: To substantially inhibit waste of materials by easily stabilizing outer diameter of a drawn glass preform as soon as its drawing is started. SOLUTION: In the processes for manufacturing and drawing the glass preform, a starting seed rod 11 having a low-viscosity part 11a at its tip made of e.g. quartz containing at least one chosen from F, Cl, B and P is used. When heated to an elevated temperature (2,000°C), the low-viscosity part 11a shows a viscosity lower than that of pure quartz but equal to or higher than that at a minimum viscosity part of the glass preform 10. At a part where drawing is started in a drawing step, variation in the outer diameter is reduced by reducing elongation difference between the starting seed rod 11 and a sintered body 13 resulting from their viscosity difference. COPYRIGHT: (C)2004,JPO
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