Arc tube for a metal halide lamp.

摘要

An arc tube (6) for a metal halide discharge lamp (2) is formed of titanium oxide doped vitreous silica. In one embodiment of the invention the doped vitreous silica is fused quartz made from a melt doped with TiO2. In a preferred embodiment, the concentration of titanium oxide in the vitreous silica is approximately 250 parts per million by weight. Metal halide discharge lamps utilizing arc tubes formed from the doped vitreous silica demonstrate improved lumen output and lumen maintenance. It is believed that arc tubes formed from the doped vitreous silica also suffer less sodium loss than arc tubes formed from conventional fused quartz. <IMAGE>