Providing the first comprehensive treatment, this book covers all aspects of the laser Doppler and phase Doppler measurement techniques, including light scattering from small particles, fundamental optics, system design, signal and data processing, tracer particle generation, and applications in single and two-phase flows. The book is intended as both a reference for more experienced users and an instructional resource for students. It provides ample material as a basis for a lecture course on the subject and represents one of the most comprehensive treatments of the phase Doppler technique to date. The book will serve as a valuable reference in any fluid mechanics laboratory where the laser Doppler or phase Doppler techniques are used. This work reflects the authors' long practical experience in the development of the techniques and equipment, as the many examples confirm.