This is an updated and revised translation of the original Japanese edition. The authors have taken a unique approach in treating laser aided diagnostics as a unified subject instead of the usual and disjointed approach of describing each application as a totally separate system. In taking this approach, they highlight the relative strengths of each method and show how they can compliment each other in the study of gases and plasmas.The first part provides a general introduction to the laser-aided study of gases and plasmas, including the various principles and hardware needed for each method. The second part describes the applications of each general system in detail.