Patent ID: 7285509

Claim:
A process for preparing a BGG glass material comprising the steps of melting BGG glass components at a melting temperature, said components consisting essentially of barium oxide (BaO) and/or barium carbonate (BaCO 3 ), gallium oxide (Ga 2 O 3 ), germanium oxide (GeO 2 ), or a precursor thereof, and a halogen component at a temperature above liquidus temperature of the BGG glass to form a BGG glass melt, wherein amounts of the BGG glass components are in the BGG glass forming region; bubbling said BGG glass components with a dry gas during said melting step; quickly cooling the BGG glass melt to avoid crystallization to below glass transition temperature of the BGG glass to form a BGG glass; annealing the BGG glass at a temperature above the glass transition temperature but below crystallization temperature; and slowly cooling the BGG glass after annealing to a temperature below the glass transition temperature to form the BGG glass material, wherein said BGG glass material has a transmission level of at least 80% over the wavelength range from about 0.5 micrometers to about 5 micrometers.