Three-dimensional displacement measurement based on the combination of digital holography and digital image correlation

A new simultaneous three-dimensional (3D) displacement measurement technique based on the combination of digital holography (DH) and digital imaging correlation (DIC) is proposed. The current DH-based 3D displacement measurement technique needs three sets of DH setups, and only the phase images are utilized in measurements, with all the intensity images discarded. In contrast, the proposed new technique only adopts a single off-axis DH setup. In the proposed technique, the phase images are used to extract out-of-plane displacements, but the intensity images (instead of being discarded) are processed by an intensity correlation algorithm to retrieve in-plane displacement components. Because the proposed technique fully takes advantage of all the information obtained by an off-axis DH without additional optical arrangements, it is simpler and more practical than the existing DH-based 3D displacement measurement technique. Experiments performed on a United States Air Force (USAF) target demonstrate that both the in-plane and out-of-plane displacements can be accurately determined by the proposed technique.