Mother glass composition for graded index lens
AssigneeNippon Sheet Glass Co., Ltd.
InventorsTetsuro Yoshii, Shigeo Kittaka, Tadashi Koyama
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Abstract
An SiO2-TiO2-Li2O-Na2O-based glass composition containing no lead oxide having incorporated therein specific amounts of specific components which are selected from oxides of the metal elements having an atomic number of 30 (Y) to 73 (Ta) and which hardly cause coloration of glass. The glass composition has a desirable refractive index, hardly undergoes devitrification, and hardly develops cracks on ion exchanging and is suitable as glass for a graded index lens.
Claims8
A mother glass composition for graded index lenses comprising the glass components:
- 45 to 65 mol % of SiO2;
- 2 to 12 mol % of TiO2;
- 2 to 22 mol % of MgO;
- 0 to 16 mol % of BaO;
- 8 to 10.5 mol % of Li2O;
- 5 to 12 mol % of Na2O;
- and
- 1 to 15 mol %, in total, of ZnO, Y2O3, ZrO2, Nb2O5, In2O3, La2O3 and Ta2O5, provided that the content of ZnO is 1 to 5 mol %, the total content of ZnO, ZrO2, Y2O3 and La2O3 is 3 to 10 mol %, and the content of each of Y2O3, ZrO2, Nb2O5, In2O3, La2O3, and Ta2O5 is 0 to 7 mol %.
A graded index lens comprising a mother glass composition, wherein the mother glass composition comprises the glass components:
- 45 to 65 mol % of SiO2;
- 2 to 12 mol % of TiO2;
- 2 to 22 mol % of MgO;
- 0 to 16 mol % of BaO;
- 8 to 10.5 mol % of Li2O;
- 5 to 12 mol % of Na2O;
- and
- 1 to 15 mol %, in total, of ZnO, Y2O3, ZrO2, Nb2O5, In2O3, La2O3 and Ta2O5, provide that the content of ZnO is 1 to 5 mol %, the total content of ZnO, ZrO2, Y2O3 and La2O3 is 3 to 10 mol %, and the content of each of Y2O3, ZrO2, Nb2O5, In2O3, La2O3 and Ta2O5 is 0 to 7 mol %.
Dependencies are inferred from the claim text.