abstract |
(57) [Abstract] [Purpose] The purpose is to prevent gas from entering from the outside of the arc tube, suppress acceleration of the devitrification reaction, and prolong the life of the metal halide lamp. [Constitution] B2O3, P2O on the outer surface of the quartz glass arc tube 5, a SiO2 glass layer containing any one of Na2O, Al2O3, etc. as an impurity. |