提出了一种正弦调制多光束激光外差二次谐波测量微冲量的新方法,将激光与工质靶作用产生的微冲量转化为扭摆的转动角度测量，基于激光外差技术和多普勒效应，把待测转角信息加载到外差信号的频率差中，经信号解调后可以得到待测转角值，通过多次测量取平均值的方法可以提高待测转角的测量精度，从而提高微冲量的测量精度。利用这种新方法，以PVC+2%C为工质靶，利用MATLAB仿真测量了激光与工质靶作用产生的微冲量，结果表明: 该测量的最大相对误差小于0.8%。

We propose a novel method of second harmonic multi-beam laser heterodyne measurement for micro impulse based on oscillating mirror sinusoidal modulation. The measurement of the micro impulse, which is converted into the measurement of the small tuning angle of the torsion pendulum, is realized by measuring the interaction between pulse laser and working medium. Based on Doppler effect and heterodyne technology, loading the information of small tuning angle to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain value of small tuning angle after the multi-beam laser heterodyne signal demodulation. Processing the weighted-average of multiple measurements improves the accuracy of small tuning angle values and eventually the precise value of micro impulse is calculated. Using Polyvinylchlorid+2%C as a working medium, this novel method is used to simulate the micro impulse generated by the interaction between the pulse laser and the working medium by MATLAB, the result shows that the relative error of this method is just 0.8%.