Comparative analysis of digital and optical speckle displacement techniques for study of in-plane surface strains

The comparative analysis of the digital speckle-displacement measurement technique and the optical speckle-displacement correlation technique is carried out. Some versions of a joint transform correlator (JTC) architecture, namely a conventional JTC, a JTC with median thresholding, a JTC with subset median thresholding, and a fringe adjusted filter JTC, are used for study of in-plane rigid body displacements. The systematic and random errors of speckle pattern's mean displacement calculated by using the mentioned above techniques are compared. The robustness of the digital speckle-displacement measurement technique and four JTC versions to input noise of speckle patterns and output noise of a correlation response is studied.