| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical glass for precision press molding, high in refractive index and dispersion properties, slight in coloration of glass, having, a lightweight, capable of being subjected to precision press molding, containing no lead oxide capable of readily providing an optical glass with characteristics of a high refractive index and high dispersion properties and no TiO2 at all. SOLUTION: This optical glass comprises a composition consisting of 17 31 wt.% of P2 O5 0-7 wt.% of B2 O3 , 19-31 wt.% of the total of P2 O5 and B2 O3 , 0-15 wt.% of BaO, 0-6 wt.% of Li2 O, 6-16 wt.% of Na2 O, 9-17 wt.% of the total of Li2 O and Na2 O, 19-50 wt.% of Nb2 O5 , 0-25 wt.% of WO3 and 10-25 wt.% of TeO2 and has <=560 yield temperature (At), >=1.73 refractive index, <=28.5 Abbe's number (νd) and <=4.0 specific gravity(Sg).
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