Phase retardation measurement with two λ/4 wave plates

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.