Digital generation of phase-shifting fringes to provide an alternative to interferometry

Digital speckle pattern interferometry is well known technique in many areas when one needs to measure micro-displacements out of the plane in biological and non-biological objects. The methodology is based on the Michelson’s Interferometer with the use of a piezoelectric actuator (PZT) in order to provide the phase-shift of the fringes and then improve the quality of the final images. The creation of the shifting images using a PZT, despite its great use, has some drawbacks, such as the cost of the apparatus, the need to apply the same displacement of the mirror repeated times, or when one need to apply the technique in moving objects. This work created digitally the phase-shift images avoiding the mechanical PZT and tested them in the digital shearography method. The proposed methodology tested a well-known object, a cantilever beam of aluminium, and a biological sample, a tooth. The results presented the ability of the proposed methodology to create the deformation map and curves with reliability and proving that it is possible to reduce the cost, to improve the robustness and also the accessibility of the digital speckle shearography pattern interferometry.