| 摘要 |
PROBLEM TO BE SOLVED: To provide a metallic vapor discharge lamp and a halogen lamp, having glass tubes with viscosity so that they efficiently absorb the energy of scattering of rupture fragments of an arc tube and can thus make the energy of the scattering sufficiently small, so that damage to outer bulb can be prevented. SOLUTION: In a metal halide lamp comprising an arc tube 1 made of quartz glass, a glass sleeve 3 placed away from the tube 1 in such a way as to surround the tube 1, and an outer bulb 2 storing the tube 1 and the glass sleeve 3, the thickness of the glass sleeve 3 is 1.0 mm or more and the glass sleeve 3 is made of glass having a viscosity of 1×10<14> to 1×10<25> poise at the temperature of lamp operation.
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