| 摘要 |
1,200,527. Optical glass. ERNST LEITZ G.m.b.H. 3 Sept., 1968 [28 Oct., 1967], No. 41822/68. Heading ClM. Glass having anomalous fractional dispersion is obtained by melting a frit comprising, in weight per cent : 5-20 of one or more metaphosphates of alkali-metals; 50-75 of metaphosphates of one or more of Mg, Ca, Sr and Ba; 2-15 TiO 2 ; 2-15 BeO; the balance, if any, consisting of other compatible constituents. Up to 7% of either or both of potassium arsenate and potassium fluorotitanate, and/or up to 10% of BaO, may also be present.
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