Beam quality of array beam from axisymmetric folded-combined CO2 laser

There are the small distances between the axes of the parallel array beams from axisymmetric folded-combined (ASFC) CO2 laser and each other due to the compact structure. Three methods are used for describing the combined array beams quality, such as, the size of focal spot, M2-factor and power in the bucket (PIB). The combined beam radius is calculated by using the second order moment. It is shown that the high quality beam can be obtained by the ASFC high power CO2 laser, and M2-factor and PIB will be influenced by the spherical aberration. The numerical examples are given to illustrate our calculated results.