| 摘要 |
PURPOSE:To easily obtain a graded index optical element having concave distribution by firing dry gel having concave dopant distribution without breaking or foaming. CONSTITUTION:When glass is produced by a sol-gel process, pore volume distribution is rendered to gel before drying so that the pore volume is increased from the central part of the gel toward the outside. Since gel having larger total pore volume becomes nonporous at a higher temp., gel is gradually made nonporous from the central part toward the outside by increasing the total pore volume from the central part toward the outside. The gas in the gel is led from the central part to the outside and the breaking and foaming of the gel is prevented. |
