Laser speckle pattern and high speed camera system for non-contact vibration displacement measurement: Accuracy and limitations

This study presents a novel non-contact vibration displacement measurement system utilizing laser speckle patterns and a high-speed camera. Conventional methods using contact sensors often suffer from mass loading effects, limiting measurement accuracy. Our approach exploits defocused speckle patterns to capture both small displacement and vibration frequency. Two video processing techniques, digital image correlation (DIC) and phase correlation, are compared to assess their accuracy and limitations in extracting pixel-level displacement, with calibration challenges addressed for mm-to-pixel conversion. Experimental evaluations demonstrate that the proposed system overcomes previous constraints, enabling reliable multi-point measurements through laser beam splitting. The findings offer valuable insights for optimizing non-contact vibration analysis and pave the way for enhanced dynamic event monitoring in various engineering applications.