Photoacoustic imaging combines electromagnetic and ultrasonic waves to provide deep speckle-free imaging with high electromagnetic contrast at a high resolution. By means of spectroscopy, photoacoustics can also provide functional sensing of physiological parameters such as the oxygen saturation of hemoglobin. This book presents the state of the art in this exciting new area of research, offering complete coverage of photoacoustic, optoacoustic, and thermoacoustic imaging. Featuring 200 illustrations, this text compares x-ray and ultrasonic images with photoacoustic images. It also discusses all potential applications of photoacoustic technology, including biomedical applications.