为了简化四频差动激光陀螺的信号读出系统，采用了一种基于FPGA实现的数字电路解调方案取代传统的合光棱镜中的1/4波片和偏振片来分离左、右旋陀螺信号。简述了四频差动激光陀螺的信号读出原理及解调电路方案，设计了主要由A/D转换器和FPGA构成的四频陀螺信号读出系统。通过Quartus II等EDA工具在软件上对系统予以了实现，并针对其主要功能模块进行了仿真验证。仿真结果表明，将四频陀螺信号转化为数字信号后，利用FPGA实现信号解调并最终达到分离左、右旋陀螺信号的方案是可行的，该方案将有助于全数字化激光陀螺的研制。

In order to simplify the signal readout system for the four-mode differential laser gyros (FMDLGs), the 1/4 waveplates and polarizes used in the conventional combining prism are replaced by a FPGA-based scheme of digital circuit to extract signals of left circularly polarized (LCP) and right circularly polarized (RCP) gyros. In this paper, the principle of readout system for FMDLG is described briefly. The scheme to read the signals of LCP and RCP gyros out with electronic circuit is introduced, and the readout system based on AD transformers and FPGA for FMDLG is designed. Then the system is customized by some EDA tools such as Quartus II, and verified the main function units of this system by simulation. The simulation result showed the feasibility to demodulate the signals and finally extract the signals of LCP and RCP gyros by FPGA after transforming the FMDLG outputs to digital signals. This scheme could be helpful for the development of fully digital laser gyros.