提出一种基于快速傅里叶变换( F F T)提取相位的方法, 分析自混合干涉信号, 不增加系统复杂度就能将激光自混合( SM LD) 微位移测量精度提高到纳米量级。(A phase extraction method based on F F T is proposed. The self mixing interference signal is analyzed, and the accuracy of the self mixing (SM LD) micro displacement measurement can be increased to nanometer level without increasing the system complexity.)