在对波片延迟量的测量中常因光源起伏影响测量精度，出现较大的测量误差，为了避开光源强度起伏的影响，提高系统的测量精度，减小测量误差，用两个标准λ／4波片与待测波片组合，使其满足一定条件等效为旋光器，搭建了一套测量系统，用角度测量替代对光强的直接测量。实验结果表明，该系统可有效避免光源强度起伏对测量结果的影响，测量精度可达0．5。。与传统测量方法相比，该测量系统具有构造简单，不受光源起伏影响，以及测量精度高等特点，是一种便捷有效的测量方法。

In the retardation measurement of wave plate,the accuracy is often influenced by the fluctuation of the light source. If the fluctuation of the light intensity is avoided,the measurement system will become simple,and the measurement accuracy will be improved. A new measurement system with a polarization apparatus was built,which is composed of two λ/4 wave plates and the measured wave plate. In the system,angle measurement substitutes direct light intensity measarement,which can effectively avoid fluctuation of the light intensity. The measurement accuracy can reach 0.5°. Compared with traditional measurement methods,it is a handy method with simpler system and higher accuracy.