For enabling a quasimonochromatic high intensity light beam to be produced by a source having a lamp equipped with a cold light mirror, a heat protection filter in the light beam path and a system for cooling the heat protection filter, the source is further provided with an interference filter and projection...http://www.google.es/patents/US4240133?utm_source=gb-gplus-sharePatente US4240133 - Quasimonochromatic light source
