中文摘要：

为了实现单色线偏振光的退偏，设计了一种新型四元结构的双折射晶体退偏器，并采用偏振光波叠加的思想方法研究其退偏性能。通过对透射光场的分析，得到了振动方位角（vAA）为0°、单色线偏振光分别以正反向入射时的退偏度表达式。理论分析与实验表明，在退偏器的楔角取适度大值的前提下，正向使用时的退偏度受到光程差影响较大，但可以通过斜入射的方法来改善；而反向的退偏度不受光程差影响，对11°以内的入射角均超过98．9％。本文方法简便、清晰，为这一类型退偏器的研究提供了新的思路。

英文摘要：

A novel quadruple birefringent depolarizer is designed for the depolarization of monochromatic linearly polarized light. Using the idea of superposition of transmitted light, its performance is studied. The formula of degree of depolarization for the forward linearly polarized light, whose vibration azimuth angle is 0, is obtained. It can be shown by theoryand experiment that the degree of depolarization changes obviously with optical path difference on the basis of wedge angle large enough. The degree of depolarization is 100% when the vibration azimuth angle takes（N/2） π （N is integer） independence of the optical path difference. However, the degree of depolarization in this case will be much better as the light is incident obliquely. The result is verified by the experiment.. And the degree of depolarization for the backward incident light is over 98. 9% for any vibration azimuth angle when the incident angle varies within 11°. So the design is feasible and the research method is such simple and clear that it can provide a new reference for the study of such depolarizer.