Electronic speckle pattern interferometer design to get maximum sensitivity on the measurement of displacement vector fields

In the present work, different geometries of interferometers with three divergent illumination beams are discussed. It is shown that the sensitivity components for each source can be measured with a maximum weight factor. The three sources were placed respectively, on x, y and near to z axis of a coordinate system. Based on our theoretical calculations it is proposed an interferometer that uses ESPI technique. Experimental results of displacements and strains are presented for one elastic surface when a torsion load is applied near to the target centre.