分析了采用分束器构建干涉型复合腔进行激光束相干合成的过程与原理.利用分束器的特征矩阵研究了分束时产生的反射与透射相移，得到了两束相干光经过分束器分束后进行相干叠加时相移满足的普适关系，从相移的角度解释了分束器一侧发生相长干涉时另一侧必然发生相消干涉这一现象.比较了分束器与光纤耦合器在激光束相干合成应用中的一些特性，并验证了所得相移关系式的正确性.

The process and mechanism of coherent combining with the interference compound cavity were analyzed.The phase-shifts caused by reflection and transmission of the beam splitter were investigated by its eigen-martix.The general relationship between these phase-shifts of two splitted beams used for coherent combining was obtained,then the fact that when constructive interference occurs in one side of the beam splitter and the destructive interference has to occur in the other side was explained in the point of phase-shift.And,some comparisons between beam splitter and fiber coupler were made when they were used for coherent combining,and the correctness of the obtained phase-shift relationship was also verified.