Arc Lamps

An arc or flash lamp is a lamp that uses a luminous and heat emission of plasma bridge formed in a gap between two conductors or terminals when they are separated. A mercury arc lamp is a discharge arc lamp filled with mercury vapor at high pressure; it gives out a very bright UV and visible light at some wavelengths including 303, 312, 365, 405, 436, 546, and 578 nm. Another arc lamp producing the so-called IPL (intensive pulse light) and often used in tissue spectroscopy and dermatology is a xenon or krypton lamp that is filled with xenon or krypton. It gives out a very bright UV and visible light in the range from 200 nm to >3.0 pm. The output spectrum of an arc lamp is a mixed emission spectrum of plasma as a heat source and spontaneous fluorescence of plasma ions. For a high energy short pulse, the temperature of arc lamp plasma can be very high (6000-10000 K) and the dominant emission is provided by heat sources with spectrum close to blackbody (see Fig. 3.1). For CW or long pulse mode, the temperature of arc lamp plasma is relatively low (3000-6000 K) and the emission spectrum has a significant portion of fluorescence light in the red and NIR spectral range.