中文摘要：

利用二维4路光纤激光环形腔被动锁相相干组束实验平台，对被动相干组束系统的光束质量进行了研究。以衍射极限倍数口因子作为光束质量的评价方法，理论分析了光束占空比以及不同锁相模式对β因子的影响，实验测量了对应不同输出功率水平的β因子。结果表明，虽然卢因子可以在一定程度上反映出不同实验条件下光束质量的差异，但是由于口因子的测量核心是确定出焦平面处83．8％环围能量（功率）比的桶尺寸，不能反映相干组束远场光斑的特点，不适合用于评价被动相干组束系统的光束质量。比较分析了β因子与光束质量，光束质量能更好地反映出相干组束的特点。

英文摘要：

Beam quality of the passive coherent beam phase-locking experimental platform of four fiber lasers combination system is studied using the ring cavity passive in two-dimensional distribution. With the times-diffractionlimited factor βas the evaluation method, the impact of duty ratio of sub-beams and different phase-locked patterns on the β factor is analyzed theoretically; and the βfactor corresponding to different output power levels is measured in the experiment. The results show that although the β factor can reflect the difference in beam quality under different experimental conditions to some extent, it can not reflect the characteristics of coherent beam patterns in the far-field because the focus of the βfactor measurement is to determine the bucket size of 83.8% encircled energy （power） ratio at the focal plane, therefore it is not suitable for the evaluation of the beam quality of a passive coherent beam combination system. A comparative analysis of the βfactor and beam quality is done, beam quality can better reflect the characteristics of the coherent beam combination.