提出一种基于激光多普勒技术和光学外差原理对高速回转机械进行扭振测量的新方法，分析了工作原理，推导出光路部分的数学模型，并通过实验分别验证了测量方法的可行性和准确性。高相干激光投射到转轴同一个截面上2点，反射光的多普勒频移正比于转轴转速，通过光学配置，使前后两个时刻的多普勒频移光信号在光探测器上发生光学混频，光电流拍差正比于转轴在两个时刻的速度差，控制两个时刻时间差很小，直接得到角加速度。与其他激光多普勒扭振测量方法相比，该方法直接测量转动角加速度，在保证测量精度的前提下，提高了扭转振动测量的实时性，极大地扩展了扭振测量的动态范围，对大型回转机械运行状态监测和故障诊断具有重要意义。

A novel measurement method for the torsional vibration of high-speed rotary machine is proposed, based on laser Doppler technique and the principle of optical heterodyne. The article analyzes its principle, worked out the mathematical model of the optical configuration, and tests the feasibility and accuracy respectively. The laser beams launch at two points of the same section of the rotating shaft. The reflected beams are shifted at frequency domain according to Doppler effect. The frequency shift is proportional to the rotating velocity. With the proper optical configuration, the beams of two successive times are heterodyned on the photo-detector, and the frequency of the photoelectric current is proportional to difference of velocity at the two times. By making the interval of the two successive times small enough so that the angular acceleration is measured directly. Compared with other measurement methods based on laser Doppler technique, the angular acceleration is measured directly, therefore the measurement of torsional vibration is more real-time and dynamic range is extended greatly. It is essential to the monitoring running state and failure diagnosis of large-scale gyration machine with high-rotational velocity.