Sources of Light

Abstract

Every usual source of light is merely a group of radiating atoms²¹. If one atom could be isolated for study, it would be found to emit radiation of a single frequency, or wavelength, during any interval throughout which it radiates. This type of radiation is often called homogeneous or monochromatic in optics or radiation physics. However, the terms homogeneous and monochromatic have inappropriate connotations in discussions of appearance and color. For colorimetry, light that consists of a narrow range or “band” of frequency or wavelength is better described by the straightforward name spectrum light. This term is employed in this volume. However, the name monochromator will be used for any device that provides spectrum light, because there is no recognized alternative. It should not cause confusion.