This book, first published in 2006, describes the theory and uses of interferometry for advanced students in physics, optics and astronomy.This book, first published in 2006, was the first on optical stellar interferometry. It covers the history, theory and future uses of interferometeric techniques. It discusses ideas and instruments used in interferometry for advanced students in physics, optics, and astronomy with an interest in astronomical interferometry.This book, first published in 2006, was the first on optical stellar interferometry. It covers the history, theory and future uses of interferometeric techniques. It discusses ideas and instruments used in interferometry for advanced students in physics, optics, and astronomy with an interest in astronomical interferometry.During the last two decades, optical stellar interferometry has become an important tool in astronomical investigations requiring spatial resolution well beyond that of traditional telescopes. This book, first published in 2006, was the first to be written on the subject. The authors provide an extended introduction discussing basic physical and atmospheric optics, which establishes the framework necessary to present the ideas and practice of interferometry as applied to the astronomical scene. They follow with an overview of historical, operational and planned interferometric observatories, and a selection of important astrophysical discoveries made with them. Finally, they present some as-yet untested ideas for instruments both on the ground and in space which may allow us to image details of planetary systems beyond our own.1. Introduction; 2. Basic concepts: a qualitative introduction; 3. Interference, diffraction and coherence; 4. Aperture synthesis; 5. Optical effects of the atmosphere; 6. Single-aperture techniques; 7. Intensity interferometry; 8. Amplitude interferometry: techniques and instruments; 9. The hypertelescope; 10. Nulling and coronagraphy; 11. A sampling of interferometriclC%