This book is about general infrared (IR) engineering, technology, practices, and principles as they apply to modem imaging systems. An alternative title to this book with appeal to managers and marketing personnel might be "Everything You Always Wanted to Know about Infrared Sensors, but Couldn't Get Answers on from Engineers." This book is not meant to be a comprehensive compendium of IR (like the Infrared and Electro Optical Systems Handbook). Rather, it is intend­ ed to complement such texts by providing up to date information and pragmatic knowledge that is difficult to locate outside of periodicals. The information contained in this book is critical in the day-to-day life of en­ gineering practitioners, proposal writers, and those on the periphery of an IR pro­ gram. It serves as a guide for engineers wishing to "catch up," engineers new to the field, managers, students, administrators, and technicians. It is also useful for seasoned IR engineers who want to review recent technological developments.