Phase-shifting digital speckle pattern interferometry: off-the-shelf setup description and application to stainless steel membrane displacement measurements
Résumé
Phase shifting digital speckle pattern interferometry (PDSPI) is well suited for micrometric displacement measurements. It is non-intrusive and without contact for the object under investigation. Speckle is generated when a beam of coherent light impinges the surface of an optically rough object. Designing the system with off-the-shelf components implies the full understanding of speckle generation, image acquisition and processing. This paper will describe the main components and their contribution to the final result, from the speckle effect to the unwrapping of the phase. The designed PSDSPI set-up allows the study from small to large areas and can produce quantitative displacement maps using phase shifting principle. As an application the object is a flat circular steel membrane closing a depression chamber. The size of the membrane is about 20 mm in diameter. The membrane deformation is measured using step by step PSDSPI process while decreasing pressure in the chamber. The results show a typical displacement of about 1 μm for 1 mbar. Quantitative profiles of the membrane deformation can be obtained. Further applications will be presented, including measurement corrections by shape of the object. Phase discontinuities will be discussed.
Domaines
Optique [physics.optics]Origine | Fichiers produits par l'(les) auteur(s) |
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