<title>Effects of chemical dose in increasing the output and system efficacy of short arc metal halide lamps</title>

Abstract

Compact LCD projectors require compact, low power metal halide lamps to achieve maximum screen brightness. We have previously described such lighting systems, taking into account ballast stability, source etendue, and collection optics. Metal halide sources have a significant advantage over high pressure xenon, high pressure mercury, and halogen sources in that the spectral power distribution of the source can be optimized for the projection system. This is in addition to the inherently greater luminous efficacy of metal halide source. We present the result of recent studies on chemical dose composition in 50 Watt, 1.2 mm arc gap, long life metal halide lamps. Through designed experiments on chemical species, dose weight, and molar composition we were able to increase the luminous output by as much as 50 percent in some cases. The optimized metal halide lamp has 50 percent more red radiation than a 50 Watt, 1.3 mm gap high pressure mercury lamp and also produces a preferred color temperature. Knowledge of the significant factors that effect color allows us to design virtually any color gamut. It was possible to match the filter characteristics of a number of projection systems.