The prism coupler was employed while light wave entry and leave wave guide, it has greatly reduced the error caused by quality of the sample and clean situation of terminal surface or bad performance of assembling the light wave of output lens. 光波出入波导均采用棱镜耦合,减少了普通测试方法因样品质量及面形误差和端面洁净情况不同或输出透镜不能很好汇聚光波而产生的误差;