| 摘要 |
PURPOSE:To obtain the titled glass filter suitable for a TV camera or the like by adding Se, C, SnO and an organic reducing agent or the like to an SiO2-Na2O-BaO-As2O3 series basic glass and heat-treating the mixture in the specified temp. CONSTITUTION:The basic glass consisting of 57-70% (by wt%) SiO2, 12-24% Na2O and/or K2O, 5-18% BaO, 0-10% one or more kinds selected from among MgO, CaO, SrO and ZnO, 0-5% B2O3, 0-3% Al2O3, 0-4% TiO2 and 0.2-0.5% As2O3 is prepared. Then 0.08-0.5pts. SeO, 0-0.5pts. MnO2, 0.2-0.8pts. C, 0.05-0.4pts. SnO and 0-0.5pts. organic reducing agent selected from among potassium hydrogentartrate, saccharose and starch are added to 100pts. basic glass. Thereafter the titled filter is obtained by heat-treating the mixture at the temp. of the collapsing point and above, the softening point and below of glass.
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