# La caractérisation de front d'onde dans un système de propagation à multi-illumination gérée par un modulateur spatial de lumière

Abstract : Phase retrieval is a cornerstone of wavefront analysis, which is finding ever wider applications in many fields where it is met under two forms: wavefront reconstruction and surface analysis. Present techniques leave opportunities for novel methods: more powerful, more efficient and especially cheaper. Whereas the most popular techniques require sophisticated optical equipement, the use of a diffractive solution makes possible the use of low cost equipment combined with a powerful intelligent digital image-processing. The aim of this study is, on the one hand, to demonstrate the feasibility of a multiview principle dealing with phase retrieval of an unknown beam and on the other, to design an experimental setup that is able to determine the phase map from a small number of captured diffraction patterns. We propose a method, called here multi-illumination'', for extracting this phase-information with the aid of a spatial light modulator which produces a range of different illuminating beams. This method involves a digital image-processing based on the Iterative Fourier/Fresnel Transform Algorithm (IFTA) principle. Two versions are developped: the first using images grabbed in a coherent imaging system, the second works with diffraction patterns obtained in a double Fresnel/Fourier setup. The capacities of the algorithm are verified both in extensive digital simulations and in an experimental setup built up with a SLM and a CCD syncronously managed by a specifically developped software. Key-words: wavefront analysis, phase retrieval, spatial light modulator, multiview, iterative Fourier/Fresnel transform algorithms.
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Submitted on : Monday, May 22, 2006 - 8:00:00 AM
Last modification on : Friday, July 31, 2020 - 10:44:03 AM
Long-term archiving on: : Monday, October 22, 2012 - 4:45:25 PM

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• HAL Id : pastel-00001748, version 1

### Citation

Alexandre Mazine. La caractérisation de front d'onde dans un système de propagation à multi-illumination gérée par un modulateur spatial de lumière. Physics [physics]. Télécom ParisTech, 2006. English. ⟨pastel-00001748⟩

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