Clad glass composition for graded-index rod lens, graded-index rod lens, and method for manufacturing the same

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+La₂to 20, and a content of at least one of TiO₂ and La₂O₃ is substantially 0 mol %.