激光自混合干涉技术是近年来兴起的一种具有很高应用价值的干涉测量技术。为提高自混合干涉的位移测量精度，在环形腔光纤激光器自混合干涉系统中引入正弦相位调制技术。分析了干涉信号的相位调制和基于傅里叶变换的解调算法，讨论了相位调制器的调制噪声和多重反馈等因素对自混合干涉测量精度的影响。使用环形腔掺铒光纤激光器和光纤相位调制器构建了实验系统，对高精度商用微位移平台的振动进行了测量，在频域中获取了自混合干涉信号的相位，并重构了位移平台的位移，获得了λ/20的位移测量精度。实验结果表明，该系统提供了一种可靠的基于全光纤传感应用的高精度位移测量方法。

In recent decades, the laser self-mixing interferometric technique has shown great promise in many applications. In order to improve the accuracy of the displacement measurement, sinusoidal phase modulating technique is introduced into a fiber ring laser self-mixing interferometer. Phase modulated interference is theoretically analyzed, and the phase demodulation algorithm of the interference signal is implemented by Fourier analysis. Error sources induced by the distortion of the interference signal in the presence of optical feedback and the phase modulator noise are evaluated in detail. The measurement setup is built by using an erbium-doped fiber laser and a phase modulator. The system is experimentally applied to reconstruct the motion of a high-precision commercial piezo actuator by acquiring the phase of self-mixing interference signal in the frequency domain, and a displacement measurement accuracy of λ/20 is obtained, providing a practically feasible solution for displacement measurement based on all optical-fiber sensing applications with high precision.