提出了一种由快轴保持正交方位放置的两片相同的液晶可变相位延迟器构成的可变纯相位延迟器结构设计。利用琼斯矩阵，从理论上推导了该结构在任意偏振光入射条件下，出射光偏振态与入射光偏振态保持一致。实验上，在两片液晶可变相位延迟器所加电压分别为1.55 V 和1.49 V 时，分别测量了入射光和出射光的偏振态，表征偏振态的入射光和出射光的Stokes 参数基本一致。上述两者结果都表明，该结构具有较好的纯相位调制特性，并给出了控制电压在1~2.7 V 范围时的相位变化。

A polarization-independent phase-only Liquid Crystal (LC) phase retarder was demonstrated by using two orthogonal identical Liquid Crystal Variable Retarders (LCVR). Based on Jones matrix theory, the relationship of polarization state between input beam and output beam was deduced. And the Stokes parameters were measured on the condition that the voltage individually applied to the two LCVRs was 1.55 V and 1.49 V. It is proved that the structure well operates in polarization-independent modulation. And the phase variation induced by voltage from 1~2.7 V is given out.