Niobium oxide in environmental friendly optical glass

General properties of environmental friendly optical glasses are reviewed. Niobium oxide plays an important role as one of the components that are substituted for lead oxide. Conversion from lead containing glasses to most lead free glasses results in the less negative anomalous partial dispersion. But lead free glasses containing niobium oxide are able to attain almost the same relative partial dispersion values as conventional lead containing glasses. In addition, chemical durability, Knoop hardness and lower specific gravity are also enhanced. (AU)