Holographic interferometry of high spatial resolution for the study of relative displacements of small grains in natural stones

摘要

Abstract: Subject of the investigation are time dependent processes that cause small particles in rough surfaces to displace or deform. These small particles must be identified in a region several cm$+2$/ in size. The method proposed is a simultaneous application of electronic speckle pattern interferometry (ESPI) and a holographic double exposure technique using suited carrier fringe systems. The time dependence of the process is observed by ESPI indicating suitable states of the process to be compared by the double exposure technique. Detection of displacement and identification of the particles takes place in the reconstruction real image of the double exposure hologram. The real image was chosen because of the better accessibility of the finely spaced carrier fringes. The resolution obtainable with this method is subject of discussion. The power of the method is illustrated experimentally.!11