转轴振动的测量和监控是旋转机械故障分析和诊断的主要手段。为了实现便携式高精度的现场测量, 提出了电子直接调制的激光多普勒相干转轴振动测量技术。通过对测量系统的分析, 推导出数学模型。结果表明, 直接调制激光束的频率, 简化了测量光路, 减小了体积, 降低了成本; 采用激光多普勒相干测量, 达到高分辨率的要求; 二次混频的设计, 解决了电磁干扰下微弱信号不好直接处理的难题; 取样积分技术的应用, 改善了信噪比, 使系统精确度更高; 该系统的测量不确定度小于0.1%。这对智能化的现场测量具有一定指导意义。

The measurement and monitoring of the vibration of the rotating shaft are the main means of the fault analysis and diagnosis of the rotating machinery. In order to realize the portable and high precision field measurement, the technique of rotating shaft vibration measurement based on direct electron-modulation laser Doppler coherent was proposed. Through analysis of the measurement system, the mathematical model was derived.The results show that, direct modulation of the frequency of laser beam simplifies the measurement of optical path, reduces the volume and cost. The laser Doppler coherent measurement meets the high resolution requirements.The design of the second frequency-mixing solves the problem of direct processing of weak signals under electromagnetic interference. The application of sampling integration technique improves the signal to noise ratio and makes the system more accurate. The measurement uncertainty of the system is less than 0.1%.This study is of certain guiding significance for the intelligent field measurement.