Displacement measurement by phase-shifting digital holography with convolution technique

Phase-shifting digital holography enables the measurement of surface displacements on an object body. In the present study, the convolution integral technique is adopted to reconstruct holographic images. The most important feature of the technique is that spatial resolution is independent on the distance of image reconstruction, and is suitable for displacement measurement of a body with depth. Also, the resolution obtained by the technique is expected to be higher than that obtained by the conventional reconstruction technique. The displacement fields are obtained using phase difference data before and after deformation. In this paper, experimental results of the case of a cantilever beam show good agreement with theory, also the algorithm developed for the convolution integral technique is shown to be effective and useful to the image reconstruction.