Laser Doppler vibrometry (LDV) offers an attractive solution when radial vibration measurement directly from a rotor surface is required. Research has demonstrated application on rough rotors (typically coated with retro-reflective tape) but a significant cross-sensitivity to the orthogonal radial vibration component occurs and post-processing is essential to resolve individual radial vibration components. Measurements on polished-circular rotors were then presented to overcome this problem. While these worked well, a limit on orthogonal vibration amplitude, as a proportion of laser beam diameter, was encountered, detracting from the practicality of the approach. This paper presents an alternative approach to measurements on polished-circular rotors in which incidence is switched from normal to oblique and a retro-reflector is incorporated into the beam path to deliver a measurement that is free from the problems encountered previously. Comprehensive theoretical and numerical analysis is presented, with experimental validation. Measurement error of around 1% was readily achieved, while cross-sensitivity to the orthogonal radial vibration component, at less than 3% for typical vibration amplitudes, was significantly lower than for alternative LDV approaches. This makes the proposed approach easily the preferred option for radial vibration measurements directly from polished-circular rotors.

中文翻译：

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使用激光测振法直接从抛光圆形转子进行径向振动测量：一种基于斜入射和逆向反射的新方法


当需要直接从转子表面进行径向振动测量时，激光多普勒测振仪 （LDV） 提供了一种有吸引力的解决方案。研究表明，该算法适用于粗糙的转子（通常涂有反光带），但对正交径向振动分量存在显著的交叉敏感性，并且后处理对于分辨单个径向振动分量至关重要。然后提出了抛光圆形转子的测量结果以克服这个问题。虽然这些方法效果很好，但遇到了正交振动幅度（占激光束直径的比例）的限制，这降低了该方法的实用性。本文提出了一种在抛光圆形转子上进行测量的替代方法，其中入射从法向切换到倾斜，并将回复反射器合并到光束路径中，以提供没有以前遇到的问题的测量。提出了全面的理论和数值分析，并进行了实验验证。很容易实现大约 1% 的测量误差，而对正交径向振动分量的交叉灵敏度（典型振动幅度小于 3%）明显低于其他 LDV 方法。这使得所提出的方法很容易成为直接从抛光圆形转子进行径向振动测量的首选选项。