This book is intended to serve as an introduction to the technology of thermal imaging, and as a compendium of the conventions which form the basis of current FUR practice. Those topics in thermal imaging which are covered adequately elsewhere are not treated here, so there is no discussion of detectors, cryogenic coolers, circuit design, or video displays. Useful infor mation which is not readily available because of obscure publication is referenced as originating from personal communications. Virtually everyone with whom I have worked in the thermal imaging business has contributed to the book through the effects of conversations and ideas. I gratefully proffer blanket appreciation to all those who have helped in that way to make this book possible. The contributions of five people, however, bear special mention: Bob Sendall, Luke Biberman, Pete Laakmann, George Hopper, and Norm Stetson. They, more than any others, have positively influenced my thinking.