General model to predict and correct errors in phase map interpretation and measurement for out-of-plane ESPI interferometers
✍ Scribed by H.J. Puga; R. Rodrı́guez-Vera; A. Martı́nez
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 736 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0030-3992
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✦ Synopsis
Out-of-plane conÿgurations used in electronic speckle pattern interferometry (ESPI), introduce phase error interpretation in extended target objects due to spatial variation of the sensitivity vector. In this paper, a general model to predict and correct the displacement measurement error and error phase map interpretation taking into account the target shape, illumination geometry, and in-plane displacement information, is presented. This model generalizes and extends previous analyses with respect to the sensitivity vector variations. The model is based on a relationship between variable sensitivity vector and the constant one. The importance of illumination geometry and in-plane displacement as factors that introduce the biggest error in the interpretation of the phase map are stressed. An analysis with practical parameters using divergent and collimated beams is presented. In order to predict and correct the error of phase interpretation, the ÿnite element method should be used to obtain in-plane proportional factors to build up the correction function. The analysis shows that the error can be large for common conÿgurations even when using collimated beam. To compute the measurement directly from the phase map, a general sensitivity function taking into account the shape and in-plane displacement information is naturally obtained from the presented analysis.