In-plane displacement measurement using digital image correlation with lens distortion correction

Two-dimensional displacement measurement using digital image correlation with lens distortion correction is described in this paper. A single cross-grating is used as a calibration reference. Using two-dimensional Fourier transform, the phases of the grating pattern are analyzed and lens distortion distribution is obtained from the unwrapped phase maps. After detecting lens distortion, the coefficients of lens distortion are determined using the least-squares method. Then, the displacement distributions without the lens distortion are obtained. The effectiveness of the method is demonstrated by applying the proposed method to the rigid body translation test and the uniaxial tension test. The results show that the proposed distortion correction method removes the effect of lens distortion from the measured displacements. By the proposed method, accurate measurements can be performed even if images are deformed by lens distortion.