This book contains everything you need to know about free-space laser beam propagation modeling and simulation, and the mathematics for target irradiance calculation. The author describes four different beam propagation methods (including the new, fast harmonic expansion method) and two direct target irradiance calculation methods. Kolmogorov statistics are used for turbulence simulations but you can easily use other models. The author also solves lots of examples with Mathcad and you can request the code.