设计了一种晶体光轴呈扇形分布的双折射型退偏器，并利用光波叠加的思想，研究了它对单色线偏振光的退偏性能，得到其退偏度的数学表达式。理论分析表明，在退偏器的楔角取值适当大的前提下，退偏度将随入射光振动方位角和光程差做周期变化：方位角为（N /2）π（N为整数）时，退偏度可达100%，不受光程差影响；方位角为（2N+1）π/4 时，退偏度最差；而改善退偏度，可以采用调整入射角的方法。实验测试结果与理论分析吻合较好，调整入射角为4°后，各方位角的退偏度均超过98.84%。因此，该设计具有可行性，而形式简便、意义清晰的分析方法可为该类型退偏器性能的分析提供新的参考。

A novel birefringent depolarizer whose optical axes are fan-shaped distribution is designed. Using the idea of superposition of transmitted light, the depolarization performance for linearly polarized light is studied. And the formula of degree of depolarization (D) is obtained. The theory shows that D changes periodically with the vibration azimuth angle (VAA) of incident light and optical path difference (OPD) on the basis of large enough wedge angle. D is 100% when VAA takes (N/2)π (N is integer), independent of the OPD. And D is the worst when VAA takes (2N+1)π/4. Adjusting the incident angle is adopted to improve D. The experiment results accord with the theory. And the D value of sample is over 98.84% for any VAA when the incident angle is 4°. So the design is feasible and the research method is so simple and clear that it can provide a new reference for the study of depolarizer.