This book provides an introduction to the most important optical measurement techniques that are applied to engineering problems. It will also serve as a guideline to selecting and applying the appropriate technique to a particular problem. The text of the first edition has been completely revised and new chapters added to describe the latest developments in Phase-Doppler Velocimetry and Particle Image Velocimetry. The editors and authors have made a special effort not only to describe and to explain the fundamentals of measuring techniques, but also to provide guidelines for their application and to demonstrate the capabilities of the various methods. The book comes with a CD-ROM containing high-speed movies visualizing the methods described in the book.