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Etude théorique en vue d'étendre le domaine de visibilité des franges, préalablement récupérées, en interférométrie holographique appliquée aux grandes déformations des corps opaques
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lutz, Boris |
| Copyright Year | 1995 |
| Abstract | In this paper, we would like to study the large déformations with holographie interferometry using the real-time technique. The first step is the recovering of the previously lost fringes by an appropriate modification at the reconstruction which compensate the rotation components. The second step is the analysis of the recovered modified fringes in order to determinate the déformation. Two vector équations derived from the first derivative of the optical path différence should ensure a sufficient contrast and spacing of the fringes by a careful choice of the modification parameters. Unfortunately, those conditions are only local and in order to make fringes visible in a larger domain, the second derivative of the optical path différence must be studied. Parameters should be determined to make this latter function quasi-constant in an extended domain by reducing the fringe curvature. The structure of the quadratic form of the second derivative reveals three différent terms related to the aberration theory of the images in holographie interferometry and containing surface curvature changes and derivative of surface strains. This last constatation is the resuit of the basic integrability équation of Gauss for curved surfaces which permits to express the variation of the rotation components by the surface strains' derivatives alone. Besides this quadratic form, the second derivative of the optical path différence along any curve contains a term related to its géodésie curvature. On the ridge of a fringe, we can easily détermine the fringe curvature if we know the components of the fringe tensor in this direction. The fringe curvature can be related to the modification parameters in the case of a repositionning error at the reconstruction, or to the reduced curvature change of Koïter-Sanders in the case of a small inextensive déformation. In the last chapter, we would briefly discuss the theory of visibility. So, the influence of the first and the second derivative of the optical path différence on the visibility of the fringes is shown for the particular case of the repositionning error of the référence source at the reconstruction. |
| File Format | PDF HTM / HTML |
| DOI | 10.3929/ethz-a-001576020 |
| Alternate Webpage(s) | https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/142438/eth-40139-01.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | https://doi.org/10.3929/ethz-a-001576020 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
