Access to the full text of the published version may require a subscription. We report on the design of an electric tube furnace that can be used for the fabrication of doped glass microsphere lasers. The tube furnace has a short hot zone of length 133 mm and is based on a quartz tube design. Doped laser glass particles, specifically Er:Yb phosphate glass ͑IOG-2͒, of ϳ1 m diameter are blown into the furnace using a 60 ml syringe and microspheres ranging in size from 10 to 400 m are collected at the output of the tube furnace in a Petri dish. The furnace operates at a wall temperature of ϳ900°C and is capable of making microspheres from glasses with glass transition temperatures of at least 375°C. High quality ͑Q ϳ 10 5 ͒ whispering gallery modes have been excited within the microspheres by optically pumping at 978 nm via a tapered optical fiber. Rights