| 摘要 |
PROBLEM TO BE SOLVED: To continue the forming of an optical element by restoring the forming surfaces of forming dies with less time loss in spite of oxidation without the need for applying coating films on the forming surfaces even if the forming surfaces are oxidized. SOLUTION: The optical element is formed by pressing the optical element by a pair of the forming dies in the state of heating the glass blank and a pair of the forming dies. The optical element is formed by heating the forming dies at a temp. below the yield point temp. of the glass blank and the oxidized layers of the forming die surfaces generated by this formation are removed by polishing and, thereafter, the forming of the optical element is continued. The forming surfaces are hardly oxidized at the temp. below the yield point and the easy removal is made possible in spite of the oxidation.
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