High-precision calibration method for the multiview measurement of the mirror–assisted digital image correlation

The plane mirror-assisted digital image correlation (DIC) technique facilitates multiview measurement, but the technology is hindered by low utilization of the plane mirror, contamination of mirror surfaces, and low calibration accuracy. To address these issues, a high-precision calibration method that employs a gauge block and fluorescent speckles has been proposed. The method establishes a symmetric relationship about the plane mirror through the fluorescent speckles on the front and rear working surfaces of the gauge block. Additionally, the gauge block is also used to calibrate the accuracy of the posture of the plane mirror during the coordinate transformation process. To verify the performance of the method, morphology reconstruction experiments of complex surfaces, dynamic experiments, and comparative analysis are performed. The results show that the reconstruction accuracy of the plane mirror (size:$150\times 150\times 1.5$ mm) after calibration was improved by 0.08 mm over the direct reconstruction accuracy of the DIC, with significant improvements in both dynamic and static measurement accuracy. With high calibration accuracy and convenient operation, this method shows great potential for application in plane mirror-assisted optical measurements.