| 摘要 |
It is an object of the present invention to provide a clad glass composition for graded-index rod lens for covering, during manufacturing, a preform glass composition lens of a graded-index rod lens that does not include PbO, in which the composition substantially does not include PbO, and expressed in mol % includes SiO2: 45 to 65, Na2O: 3 to 30, K2O: 0 to 10, MgO: 0 to 15, BaO: 0 to 20, where Na2O+K2O: 3 to 35 and MgO+BaO: 0 to 25, and furthermore includes B2O3: 0 to 15, ZnO: 0 to 10, TiO2: 0 to 10, Y2O3: 0 to 7, ZrO2: 0 to 7, Nb2O5: 0 to 7, In2O3: 0 to 7, La2O3: 0 to 7, Ta2O5: 0 to 10, where B2O3+ZnO+TiO2+Y2O3+ZrO2+Nb2O5+In2O3+La2O3+Ta2O5: 0 to 20, and a content of at least one of TiO2 and La2O3 is substantially 0 mol %.
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