Adaptive optics is a powerful new technique used to sharpen telescope images blurred by the Earth's atmosphere. This authoritative book is the first dedicated to the use of adaptive optics in astronomy. Mainly developed for defence applications, the technique of adaptive optics has only recently been introduced in astronomy. Already it has allowed ground-based telescopes to produce images with sharpness rivalling those from the Hubble Space Telescope. The technique is expected to revolutionise the future of ground-based optical astronomy. Written by an international team of experts who have pioneered the development of the field, this timely volume provides both a rigorous introduction to the technique and a comprehensive review of current and future systems. It is set to become the standard reference for graduate students, researchers and optical engineers in astronomy and other areas of science where adaptive optics is finding exciting new applications.