Abstract
The Schlieren method intends to reveal the elevation of a refractive fluid–fluid interface. The method is based on a comparison of images of a single pattern placed at the bottom of the container. Accurate measurements can be obtained with a simple and low-cost optical setup. However, it is restricted to weak interface deformations, weak slopes and weak paraxial angles. To overcome these limitations, we propose an enhanced optical setup that uses a bitelecentric objective and a double pattern. Thanks to this new setup, we avoid geometrical approximations and we extend the method to moderate/large deformations. Moreover, the proposed method does not depend on the liquid depth and could be used in various applications.
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Acknowledgements
We thank Y. E. Corbisier for his support to draw 3D sketches and pictures for this paper.
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This work is financially supported by the University of Liège through the CESAM Research Unit.
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JM, GL and MP contributed to the conception of the proposed method. JM, MP and NV wrote the manuscript.
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Metzmacher, J., Lagubeau, G., Poty, M. et al. Double pattern improves the Schlieren methods for measuring liquid–air interface topography. Exp Fluids 63, 120 (2022). https://doi.org/10.1007/s00348-022-03467-w
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DOI: https://doi.org/10.1007/s00348-022-03467-w