| 简介 |
PROBLEM TO BE SOLVED : To provide a mercury-free high-pressure short-arc discharge lamp but has a lamp voltage as high as that of a mercury-contained high-pressure discharge lamp, and to provide an optical device comprising the same.
SOLUTION : This high-pressure discharge lamp comprises a translucent airtight container 1 having a discharge space therein; a pair of electrodes 2 sealed in the airtight container, the electrodes having an inter-electrode distance D of 2 mm or less and facing the discharge space; and an ionizing medium sealed in the airtight container and substantially being mercury-free while it contains thulium (Tm) halide, zinc (Zn) halide and rare gas. The zinc (Zn) halide is less than 20% to 90% by mass of all metal halides sealed in the airtight container, and a ratio Vl/D of a lamp voltage Vl (V) to the inter-electrode distance D (mm) satisfies the following formula, 20
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