| 摘要 |
863,352. Optical glass compositions. LEITZ G.m.b.H., E. Sept. 3, 1959 [Sept. 20, 1958], No. 30099 /59. Class 56. An optical glass having a high refracture index, mean dispersion and an anomalous partial dispersion comprises lead phosphate and/or lead borate and boric acid, the glass being made from a mix in which, in addition to the lead phosphate, lead borate and boric acid, oxides of the second main and secondary group such as alkaline earth oxides, zinc and/or cadmium oxides, aluminium oxides, tantalum and/or niobium oxide, zirconium oxide and lantharum oxide are contained. Preferred percentages by weight are lead borate and/or lead phosphate 45 to 70 ; boric acid 10 to 30 ; tantalum oxide 2 to 15; aluminium oxide 8 to 15; zinc and/or cadmium oxide 0 to 15; zirconitun oxide 0 to 15 ; alkaline earth oxide (particularly CaO) 0 to 15; rare earth oxide 0 to 7. The alkaline earth oxide is preferably in the form of the tantalate. Particular examples are given.
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