| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a heat treatment method which lowers the virtual temperature of synthetic quartz glass, shortens the treatment time and enhances productivity. SOLUTION: The synthetic quartz glass having a target virtual temperature is rapidly obtained by setting >=1 intermediate virtual temperatures within a temperature range between an initial virtual temperature and the target virtual temperature in order to lower the virtual temperature of the synthetic quartz glass, holding the synthetic quartz glass at the intermediate heat treatment temperature corresponding to the intermediate heat treatment temperature and stepwise lowering the intermediate virtual temperature, then holding the synthetic quartz glass at the final heat treatment temperature.</p> |
