提出了一种差动式可辨向激光多普勒扭转振动测试仪 ,计算并分析了激光多普勒技术的双相检测和矩形光栅的衍射光强分布。采用相位光栅作为光学混频器件 ,提高了测量的信噪比并充分地利用了光能。实验表明 ,该系统能有效地实现旋转轴可辨向扭转振动的测量 ,并可获得较高的精度 A differential retarder laser Doppler torsional vibration tester was proposed to calculate and analyze the two-phase laser Doppler detection and diffraction grating rectangular light intensity distribution. The use of phase gratings as optical mixing devices improves the signal-to-noise ratio of measurements and makes full use of light energy. Experiments show that the system can effectively measure the torsional vibration of the rotating shaft and obtain higher accuracy