Optical Lever-Based Vision Method for Blade Modal Measurement

Vision-based techniques for structural vibration modal measurement enable full-field, non-contact vibration data acquisition and have attracted growing interest in recent years. However, their widespread adoption is hindered by inherent limitations in detection accuracy. To address this challenge, this paper introduces a novel vibration measurement method based on optical lever amplification. The proposed approach involves strategically placing reflective mirrors on the structural surface to redirect a laser beam onto a predefined plane. Structural vibrations induce measurable displacements of the reflected laser spot, which are then captured via a high-resolution camera for precise dynamic analysis. The proposed method offers two key advantages: (1) the optical lever mechanism amplifies subtle vibrations, significantly improving measurement sensitivity, and (2) spatially multiplexing vibrations from multiple distant points into a compact observation area enables high-resolution monitoring with a single close-range camera. Experimental validation through modal testing on a small wind turbine blade confirms the method's superiority, demonstrating markedly higher accuracy compared to conventional vision-based vibration detection techniques.