报道了双折射双频激光器输出光偏振特性的实验研究。实验发现双折射双频激光器两端输出的线偏振光的偏振方向并不一致，而相互有一定的旋转角度。实验也再次证明了激光器输出的是正交线偏振光，而不是晶体本征模的椭圆化了的偏振光。

In this paper we discuss the polarization characteristics of a He-Ne laser with a rotatable quartz plate in its cavity (LRQP). We have found that the output of the LRQP is two mutually Perpendicularly plane polarized light. Most importantly, it is obsevered that the polarization orientations of the front beam and the back beam from laser tube are different. There is a relative rotatory angle between them. When we rotate the quartz,the polarization orientations of both the front beam and the back beam vary with the rotation of the quartz plate. And the relative rotatory angle between the front beam and the back beam changes too.