The material from this book was derived from a popular first-year graduate class taught by James M. Palmer for over twenty years at the University of Arizona College of Optical Sciences. This text covers topics in radiation propagation, radiometric sources, optical materials, detectors of optical radiation, radiometric measurements, and calibration. Radiometry forms the practical basis of many current applications in aerospace engineering, infrared systems engineering, remote sensing systems, displays, visible and ultraviolet sensors, infrared detectors of optical radiation, and many other areas. While several texts individually cover topics in specific areas, this text brings the underlying principles together in a manner suitable for both classroom teaching and a reference volume that the practicing engineer can use. The level of discussion of the material is suitable for a class taught to advanced undergraduate students or graduate students. Although this book is not a theoretical treatment, the mathematics required to understand all equations include differential and integral calculus. This text should be foremost in the toolkit of the practicing engineer or scientist working on radiometric problems in areas of optical engineering, electro-optical engineering, systems engineering, imagery analysis, and many others, allowing the technical professional to successfully apply radiometric principles in his or her work. James M. Palmer (1937-2007) was a research professor emeritus in the College of Optical Sciences, University of Arizona. He received his AB in physics from Grinnell College in 1959, and his MS and PhD degrees in optical sciences in 1973 and 1975, respectively, from the University of Arizona, specializing in radiometry and infrared systems. Prior to attending the University of Arizona, he worked in industrial positions at Hoffman Electronics Corporation and Centralab, Semiconductor Division of Globe Union, Inc. Over a career spanning more than 40 years, he authored or coauthored more than 60 technical papers on many aspects of radiometry and photometry, and he was named Fellow of SPIE in 2003. Other awards include a NASA Group Achievement award for his work on the Pioneer Venus Mission (1979), a Tau Beta Pi Teacher of the Year Award (1992), and a Non-Traditional Student Teaching Award from the University of Arizona (1993). He taught numerous short courses at SPIE conferences, CIE meetings, and conferences of the Optical Society of America. He served as a consultant on commercial and government projects. Dr. Palmer was a brilliant lecturer whose former students, worldwide, have expressed gratitude for the knowledge they gained under his tutelage. Barbara G. Grant received her BA in mathematics from San Jose State University in 1983, and her MS in optical sciences from the University of Arizona in 1989, where her graduate research focused on the absolute radiometric calibration of spaceborne imaging sensors. She was subsequently employed at Lockheed Missiles and Space Company, Sunnyvale, California, where supported by excellent management, she pursued problems in infrared sensor calibration and postflight data analysis of electro-optical payloads. She also worked as a NASA contractor, overseeing integration and test of imager and sounder payloads on the GOES weather satellite, for which she received two NASA awards. She is the author of two book-length volumes of market research for process spectroscopy instruments. Since 1995, her consultancy, Lines and Lights Technology, has addressed problems in systems engineering, infrared imaging and data analysis, UV measurement, and spectroradiometry, among other areas.