The carbon arc furnishes the brightest source of infrared readily obtainable, but the interfering absorption spectra of atmospheric CO2 and H2O are difficult to avoid when using it. An infrared source is described consisting of a tungsten ribbon formed in the shape of a cavity, and heated electrically to 2900°K, in an inert atmosphere. The power required is 390 watts. Such a source furnishes a signal two to four times that of the conventional Globar over the rocksalt spectral region. While only about half as bright as the carbon arc, it can be used with an optical path free of atmospheric absorption.
J. H. TAYLOR, C. S. RUPERT, and JOHN STRONG, "An Incandescent Tungsten Source for Infrared Spectroscopy," J. Opt. Soc. Am. 41, 626-629 (1951)