Applications of high-power lasers are very important, especially for cutting and welding. As it is known, laser-beam characteristics have not constant value in time. So we may have suitable testing methods which allow us to determine the principal beam characteristics. The testing methods have to be very accurate, very efficient and in the same time very short as duration. We must apply a 3-dimensional intensity analysis, to the photonic beam we are studying. The number of industrial applications of lasers is increasing. An important thing is to know the optical characteristics of the laser that we study. Only the complete knowledge of the laser parameters allows controlling the process. For each laser system is very important to know the parameters i.e. their dynamic, in order to establish the correct performances. The correct information about the beam is not always possible to obtain. Various physical models help to understand the behavior of the laser beam. The best is if we have complete quantitative information about the photon beam. The definition of the beam diameter is not standardized. In order to do a comparison between different lasers, it is important to know the method that was applied to determine the beam diameter.