信号的不对称性是激光自混合干涉效应的重要特性之一,它提供了对物体运动方向的直接判别依据。利用双镜等效模型,对自混合干涉效应进行了理论分析,推导出干涉信号理论模型的数学表达式,阐述了信号不对称性形成的机理；仿真结果与已有的实验结论是一致的。

The asymmetry of the signal is one important character of the self mixing interference effect, which leads to the possibility of directional discrimination in the Doppler velocity measurment or displacement measurment. Theoretical models are given by using a two mirror cavity model, which explains the asymmetry of the self mixing interference signal successfully. Simulation results are given which are consistent with the experimental ones.