为了对双声光调制器(AOM)的频差进行高精度检测，设计了一种基于频谱校正的外差干涉检测方法及实验系统。通过测量外差干涉信号的频率，获得双AOM 的实际频差大小。信号频率的精确提取采用加Hanning 窗的比值频谱校正法。仿真分析了利用不同信噪比信号对频差的检测精度与采样点数的关系，并设计搭建实验系统对一组双AOM 的频差进行检测，结果表明，所采用的算法对双AOM 频差的检测精度优于2 Hz。该检测方法可以为高精度外差测量系统的误差分析提供有效参考。

In order to carry out high precision detection of frequency shift error of the acousto-optical modulator (AOM), a heterodyne interferometer detection method and an experimental system are designed. By measuring the frequency of the heterodyne interference signal, the actual difference frequency of the double AOM can be obtained. Spectrum correction algorithm using Hanning window is used for precise frequency correction. The relationship between detection accuracy of the difference frequency and sampling number by signals with different SNR is simulation analyzed, and the difference frequency of a pair of AOMs by designed experimental system is also detected. The simulation and experimental results show that the detection accuracy of the method used for difference frequency of double AOMs is better than 2 Hz. The method can provide valid reference for error analysis of high precision heterodyne detection system for application.