Preliminary study about the beam quality in laser material processing

In this paper,from the point of material processing,we have discussed the possibility of using M2 factor to evaluate laser beam quality,It has been pointed out that M2 factor is suitable for evaluation of beam quality in the so-called penetrating processing(i. e. weldding,cuting.drilling,etc.),but it's not suitable in the so-called surface processing(i. e. surface heat treatment.marking,etc.)