Laser Spot-Assisted Long-Distance Visual Measurement of Structural Vibration

Visual vibration measurement technologies have received more and more attention due to their non-contact and full field measurement characteristics. However, such techniques in practical applications, especially in measuring vibration of large structures can also result in low spatial resolution of images due to long-distance measurements, which in turn leads to insufficient detection capability of small vibrations and limits the effectiveness of structural health monitoring. In this paper, a laser spot-assisted long-distance vibration measurement method for large structures is proposed, in which the structural vibration is converted to ground spot movement by installing a laser light source on the structure, and the indirect measurement of structural vibration is realized by detecting the movement of the laser spot at a close distance. The proposed method not only converts the structural vibration long-distance visual measurement problem into a close spot vibration measurement problem, which improves the image resolution, but also the spot vibration has a significant amplification effect on the structural vibration, which again improves the signal-to-noise ratio of the vibration detection results. The effectiveness of the proposed method is verified by simple experiments under laboratory conditions.