Fringe modification in holographic interferometry applied to the determination of strain and rotation

The work describes a geometrical modification that can be applied to the holographic arrangement during reconstruction in order to obtain more flexibility in the evaluation of interferometric fringes. In the proposed arrangement, the displacement of the reference sources or of the holographic plate (HP) is an order of magnitude greater than the modification of the fringes. This amplification reduces the precision required for the measurements and for the repositioning of the HP. In addition, it is shown that the two independent components of the fringe vector can be determined by compensating them with two different modifications. The strain-tensor components can be deduced by repeating this operation for two more directions of observation.