Recent advances in infrared spectrophotometry have led to increased concern with the effects of radiation emitted by elements other than the source, for example, samples, reference beam attenuators, and the monochromator itself. Present levels of precision of measurement and purity of radiation are in some cases good enough that the effects of extraneous radiation can become significant, even with room temperature samples. Of particular interest are the areas of far-infrared spectroscopy, the study of very dense or highly reflecting samples, and the use of rotating sectors for photometric calibration. The magnitude of the expected effects of extraneous radiation will be discussed for several photometer systems, and the results of some experimental measurements will be described.
James E. Stewart, "The Effect of Extraneous Radiation on Photometric Accuracy of Infrared Spectrophotometers," Appl. Opt. 2, 1141-1146 (1963)