| 摘要 |
PURPOSE:To industrially and stably produce the title glass having a specified refractive index, a specified Abbe's number, specified anomalous dispersibility and satisfactory optical durability by using metaphosphates, fluorides and oxides of rare earth elements satisfying a specified compsn. CONSTITUTION:This optical glass consists of, by weight, 20-32%, in total, of 15-32% Al(PO3)3, 0-10% Ba(PO3)2, 0-10% Sr(PO3)2, 0-10% Ca(PO3)2 and 0-10% Mg(PO3)3 (metaphosphates), 55-75%, in total, of 20-70% BaF2, 5-40% SrF2, 0-15% CaF2, 0-10% MgF2, 0-5% AlF3 and 0-5% GdF3 (fluorides) and 5-22%, in total, of 5-22% Gd2O3, 0-7% La2O3, 0-10% Y2O3 and 0-10% Yb2O3 (oxides of rare earth elements) and has such optical characteristic values as 1.54-1.60 refractive index (nd) and 68-75 Abbe's number (nud) and anomalous dispersibility represented by >=0.537 partial dispersion ratio.
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