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Read the articleAUTHORS
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Jean-Pierre PRENEL: Professor at the University of Franche-Comté - Head of the Optical Metrology and Microtechnology Team at the Belfort Institute of Energy Engineering
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Paul SMIGIELSKI: Doctor of Science - Engineer from École Supérieure d'Optique ESO - Scientific Director of the Franco-German Research Institute Saint-Louis - Co-founder of HOLO 3 - ENSPS Professor at Louis Pasteur University, Strasbourg
INTRODUCTION
In this chapter, we consider optically transparent objects with refractive index variations, such as aerodynamic or hydrodynamic flows, plasmas or certain optical materials subjected to various stresses.
From an optical point of view, such objects are phase objects (characterized only by variations in optical path). They are not directly visible by forming their image on a photographic receiver, which is only sensitive to lumination (product of illuminance and exposure time).
To visualize them, we need to transform them into amplitude objects, either using strioscopic or interferometric techniques, for example, or by introducing light-scattering microparticles into the medium (as in the case of flows).
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