Deterministic phase retrieval interferometry

An interferometry method based on reconstructed wavefronts obtained via deterministic phase retrieval with speckle illumination is demonstrated numerically and experimentally. A refractive sample is illuminated with a partially-developed speckle field and the transmitted light is detected and processed using the transport-of-intensity equation to retrieve the phases at different loading states. The difference between retrieved phase maps is then used to evaluate the refractive index change due to mechanical loading. The interferometry method affords a simple setup (because no reference beam is needed) and offers direct calculations of the phases and phase difference maps.