Sandwich hologram interferometry 5: Measurement of in-plane displacement and compensation for rigid body motion

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Abstract
Sandwich holography has been used for measurements of in-plane displacement of an object. The sign of the displacement is found by tilting the sandwich hologram during reconstruction. Fringes caused by in-plane rigid body motion can be compensated for, and local displacements evaluated. It is shown that an in-plane motion of more than 1 mm of the object placed at a distance of about 1 m from the plates can be compensated for and a local tilt of 1.5 × 10−3 degrees evaluated. A comparision between conventional evaluation and evaluation of sandwich holograms by measuring the tilt angle of the plates to calculate an object’s displacement is shown with a series of experiments.