对离轴光线通过电光晶体时产生的退偏情况作了理论和实验研究。理论计算表明:当晶体厚度一定时,退偏损耗在一定范围内随离轴角度的增加而增加,随着入射光偏振方向偏离竖直方向的增大而增大。采用厚度为10mm的KDP晶体,实验测试了入射光偏振方向在竖直方向以及同竖直方向成45°时的退偏损耗。实验结果与理论计算的结果符合较好。 Theoretical and experimental studies on the depolarization induced by the off-axis light passing through the electro-optic crystal are given. The theoretical calculation shows that when the crystal thickness is constant, the depolarization loss increases with the increase of the off-axis angle within a certain range and increases with the deviation of the polarization direction of the incident light from the vertical direction. Using a KDP crystal with a thickness of 10 mm, the depolarization loss of the incident light in the vertical direction and at 45 ° in the vertical direction was experimentally tested. The experimental results are in good agreement with the theoretical ones.