Abstract: A method of detecting a leak in an outer jacket of a metal halide lamp having an arc tube inside the outer jacket and operated by a ballast, where the ballast monitors an electrical characteristic of the lamp during start and detects a leak in the outer jacket when the electrical characteristic deviates from that of a corresponding metal halide lamp whose outer jacket does not have a leak. The electrical characteristic is one of six markers, namely (1) V?(E) at a predetermined E, where V?(E) is a derivative of lamp voltage V as a function of cumulative energy E delivered to the ballast since ignition, (2) a value of E at which V?(E) reaches a maximum, (3) V at a predetermined E, (4) a local maximum of V?(E) up to a predetermined E, (5) a global maximum of V?(E), and (6) E required to achieve a predetermined V.

Abstract: Metal halide lighting with good color during dimming may be obtained. An appropriate balance of commonly used metal halides (NaI, DyI3, CeI3, CaI2, TlI) is dosed in the lamp. No mercury is used. A higher than typical xenon fill pressure from 50 to 500 Kilopascals may be used to help control thermal properties and voltage. If necessary, modulation of the power at acoustic resonance frequencies may be used to straighten and center the arc. Efficient and pleasant white output is obtained. As the power is reduced, the chromaticity either (1) remains fairly constant or (2) drifts acceptably towards warm pinkish colors. Large factors of attenuation in output can be realized. The lumen output was reduced by at least a factor of twenty in one sample as the power was dimmed from 70 to 20 watts.

Abstract: A discharge lamp system and method of operating a discharge lamp system in which vertical segregation of vapor phase species is reduced. Lamp power is modulated with an arc-straightening frequency and with a frequency that excites a combination radial plus longitudinal acoustic mode of the lamp. The combination radial plus longitudinal acoustic mode may be a combination first radial mode and nth longitudinal acoustic mode and may be excited with a single power frequency or a swept power frequency range. The two frequencies may be provided at the same time, or separately where the modulation at the arc-straightening frequency is 2 to 16 times longer than a subsequent modulation at the combination radial plus longitudinal acoustic mode.

Abstract: A method of operating a discharge lamp includes modulation of lamp power with a first longitudinal mode frequency to reduce segregation of the vapor phase species within the arc tube. The first longitudinal mode excitation frequency is determined by the acoustic response spectrum observed at an upper region of the arc tube when operated vertically. A frequency in an arc-straightening frequency range may also be added to the input power to straighten and center the arc.

Abstract: An electrodeless high intensity discharge lamp with a lamp fill material including gallium iodide has been found to be more efficient in generating light in general, and more efficient in generating blue light. The very small size of the lamp, in combination with the high intensity in a relatively narrow blue spectral range make the lamp particularly useful in supplying blue light to a fiber optic. The relative efficiency of the lamp increases its value. In combination, the lamp provides a useful, efficient source of blue light as an input source for optical fiber, and other systems for medical and other processes using blue light as a process element.