This text covers the range of subjects necessary for the understanding of modern infrared-imaging systems at a level appropriate for seniors or first-year graduate students in physics or electrical engineering. The first six chapters focus on fundamental background issues of radiation detection, beginning with the basics of geometrical optics and finishing with a discussion of the figures of merit used for describing the signal-to-noise performance of a detector system. Other topics include radiometry and flux-transfer issues, basic radiation-detector mechanisms, and random-process...