针对激光反馈干涉术，提出基于相位凝固技术的调制解调方法，用以提高位移测量的分辨率，并设计了利用相位调制器进行调制的位移测量系统.利用调制器进行外腔相位调制，采集调制相位相对固定的干涉光信号，通过解调重构得到被测的位移信息.进行了信号调制、采样、重构技术的研究以及误差分析，并通过仿真验证了方法的可行性.结果表明，采用5点相位凝固采样技术，测量准确度可以达到λ/20.此方法可提高激光反馈干涉术的测量分辨率，实现信号实时采集处理，可用于位移的实时测量.

For optical feedback interferometry, a modulation and demodulation method based on phase-freezing technology was brought forward to increase the measurement resolution. And a displacement measurement system with phase modulator was designed. The phase of the outer cavity was modulated by the modulator, and interference signals that have fixed modulation phases were collected. Then displacement information of the target can be observed by demodulation and reconstruction. Signal modulation, sampling, reconstruction technology and error analysis were studied, and the feasibility of this method was verified by simulation. The results demonstrate that the accuracy can be up to λ/20 using five-point phase-freezing sampling. This method can enhance the accuracy of optical feedback interferometry, and process signals in real time. So it can be used in real time displacement measurement.