为了提高四频差动激光陀螺的精度，对其左右旋模式光学解调分离方法进行了理论分析和实验研究。根据陀螺输出光偏振特性，分析了椭圆偏振误差对左、右旋模式光学解调分离的影响机理。定义了分离后左、右旋模式输出信噪比，对该影响进行了量化，信噪比越大对解调输出影响越小。基于仿真计算和实验验证，给出光学解调系统中偏振片安装角度与输出信噪比的关系，指出调节偏振片安装角度是一种工程上有效提高信噪比的方法，并提出一种新的偏振片角度选取的分离方法剔除法。与该陀螺研制初期的提取法获得的信噪比进行了对比，理论计算和实验结果一致表明，剔除法优于提取法。

In order to improve precision of multioscillator ring laser gyroscope (MRLG), the separation left-handed circular polarization (LCP) from right-handed circular polarization (RCP) based on MRLG with optical signal processing is studied both theoretically and experimentally. Considering that the polarizations of optical modes which are exported from MRLG influence the separation LCP from RCP, mechanism of influence is analyzed. After the separation, defining the signal-to-noise ratio（SNR） of the LCP or RCP, the value of the influence is derived. The higher of SNR, the smaller of the influence. Based on the study of theory and experimentation, the relationship between SNR and angle of sheet polarizer which is installed in the system of optical signle processing is presented. It is found that the SNR can be enhanced by adjusting the angle of sheet polarizer efficiently. A new method of separation LCP from RCP named “eliminating” is advanced by optimization installation of sheet polarizer. Compared with the earlier method named “extracting”, the new method is better than the earlier one. The result is proved both by theory and experiment.