Patent ID: 8102121

Claim:
A single-ended ceramic discharge lamp comprising: a discharge vessel, the discharge vessel having a cupulate body portion and a stem both formed of a ceramic material, the cupulate body portion being rotationally symmetric about a central axis and having an inner surface, an outer surface, a rim and a base, the stem extending outwardly from the base and having two electrode assemblies; a light-transmissive end cap sealed to the rim of the cupulate body portion, the end cap and the cupulate body portion enclosing a discharge cavity, the discharge cavity containing a discharge medium; each electrode assembly having an electrode tip that protrudes into the discharge cavity, a feedthrough portion that is sealed in the stem, and a lead end for connecting to a source of electric power, the electrode tips of the electrode assemblies defining an arc gap; and at least one of the inner surface or outer surface of the cupulate body portion comprising an optical surface wherein the arc gap is positioned at a focus of the optical surface.