| 摘要 |
PROBLEM TO BE SOLVED: To reduce a time necessary for contracting a glass fine particle deposited body and for making it transparent without causing axis deviation. SOLUTION: The method of heating the glass fine particle deposited body G obtained by depositing glass fine particles on a glass rod G1 and making it transparent includes: a degassing step for heating the glass fine particle deposited body under a reduced atmosphere to remove a gas in the glass fine particle deposited body; a first preliminary contracting step for heating the glass fine particle deposited body G at a temperature in a range within≥1,350°C and≤1,420°C until the difference between the outer surface temperature of the glass fine particle deposited body G and the temperature of the boundary of the glass fine particle deposited body G and the glass rod G1 reaches≤100°C; a second preliminary contracting step for heating the glass fine particle deposited body G at a temperature by≥10°C and≤60°C higher than that in the first preliminary contracting step after the preliminary contracting step; and a vitrifying step for making the glass fine particle deposited body G transparent by heating the glass fine particle deposited body G at a temperature in a range of≥1,480°C and≤1,600°C after the second contracting step. COPYRIGHT: (C)2009,JPO&INPIT
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