"In the chapter 2 started at with the Spatial mode size analysis of a diode-side-pumped Nd:YVO4 laser resonator, when a laser system is to be constructed, it is important to optimize the spatial characterisation of the laser output beam. These spatial mode spot size analysis have been done for self-adaptive holographic laser oscillators in order to determine the self-consistent configuration, as well as the transient evolution and a good control of the mode spot size. Here, we report on a spatial mode spot size analysis of a diode-side-pumped laser resonator that may be thought to operate in continuous wave. The resonator is conformed by a salb of Nd:YVO4 crystal acting as the active laser medium."