Hermite-Gaussian beams are a type of laser beam characterized by their coherent light source and electromagnetic field properties, which are well approximated by Gaussian functions. They are particularly useful in engineering calculations, such as when determining the necessary specifications for laser applications like bouncing beams off lunar retroreflectors. The waist size of a Gaussian beam is crucial, as it affects beam divergence and overall performance. Additionally, Hermite functions can be used to analyze different modes of oscillation in lasers, which is vital for mode selection. Understanding these concepts is essential for effectively utilizing lasers in various applications.