When the analyzer was located in four angles, a photoelectric detector was used to gather the energy of laser, so we can calculate the retardation of wave plate with the phase shifting.

• 测量装置采用了步进电机带动检偏器旋转，运用光栅编码器测角装置测量检偏器的转动角度，使用光电探测器采集检偏器在四个方位角度的光强值，根据移相算法得出波片的相位延迟角。