摘要 |
The invention relates to an ultra-high pressure mercury lamp (10) in which both devitrification and also breakage of the discharge vessel (11) can be eliminated. In the ultra-high pressure mercury lamp (10), there is a pair of opposed electrodes (13,14) in a fused silica glass discharge vessel (11) filled with at least 0.15 mg/mm 3 mercury, and an alkali metal concentration in the area from the inside surface of this discharge vessel (11) to a depth of 4 µm that is at most 10 wt. ppm. |