2 articles
Electronic speckle pattern interferometry
Electronic speckle pattern interferometry (ESPI), also called TV holography, is a non-contact optical metrology technique that measures surface displacement and deformation from laser speckle, developed from 1971 onward.
Speckle pattern
A speckle pattern is a granular pattern of randomly bright light grains formed when coherent light scatters from a rough surface or through a scattering medium.