Abstract
In this paper, we present an optical profilometric technique that allows for single-shot global measurement of free-surface deformations. This system consists of a high-resolution system composed of a videoprojector and a digital camera. A fringe pattern of known characteristics is projected onto the free surface and its image is registered by the camera. The deformed fringe pattern arising from the surface deformations is later compared to the undeformed (reference) one, leading to a phase map from which the free surface can be reconstructed. Particularly, we are able to project wavelength-controlled sinusoidal fringe patterns, which considerably increase the overall performance of the technique and the quality of the reconstruction compared to that obtained with a Ronchi grating. In comparison to other profilometric techniques, it allows for single-shot non-intrusive measurement of surface deformations over large areas. In particular, our measurement system and analysis technique is able to measure free surface deformations with sharp slopes up to 10 with a 0.2 mm vertical resolution over an interrogation window of size 450 × 300 mm2 sampled on approximately 6.1 × 106 measurement points. Some illustrative examples of the application of this measuring system to fluid dynamics problems are presented.
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Notes
As a matter of fact, these conditions are not necessary but strongly simplify the equations. Moreover, Chan et al. (1994) have showned that the parallel–optical-axes geometry provides a wider range of measurement.
In the case of a transparent liquid, projection onto its free surface is attained by the addition of dye. See Sect. 3.1. for further details.
References
Aharonov Y, Bohm D (1959) Significance of electromagnetic potentials in the quantum theory. Phys Rev 115:485–491. doi:10.1103/PhysRev.115.485
Benetazzo A (2006) Measurements of short water waves using stereo matched image sequences. Coast Eng 53:1013–1032
Berry MV, Chambers RG, Large MD, Upstill C, Walmsley JC (1980) Wavefront dislocations in the Aharonov–Bohm effect and its water wave analogue. Eur J Phys 1:154–162
Chan P-H, Bryanston-Cross PJ, Judge TR (1994) Studies of Fourier transform profilometry. In: Moorhead RJ, Silver DE, Uselton SP (eds) Proceedings of SPIE, visual data exploration and analysis, vol 2178, pp 165–176
Chen W, Hu Y, Su X, Tan S (1999) Error caused by sampling in Fourier transform profilometry. Opt Eng 38:1029–1034
Cochard S, Ancey C (2008) Tracking the free surface of time-dependent flows: image processing for the dam-break problem. Exp Fluids 44:59–71
Coste C, Lund F (1999) Scattering of dislocated wave fronts by vertical vorticity and the Aharonov–Bohm effect. II. Dispersive waves. Phys Rev E 60:4917–4925. doi:10.1103/PhysRevE.60.4917
Coste C, Lund F, Umeki M (1999) Scattering of dislocated wave fronts by vertical vorticity and the Aharonov–Bohm effect. I. Shallow water. Phys Rev E 60:4908–4916. doi:10.1103/PhysRevE.60.4908
Cox CS (1958) Measurement of slopes of high-frequency wind waves. J Mar Res 16(9):199–225
Dabiri D (2003) On the interaction of a vertical shear layer with a free surface. J Fluid Mech 480:217–232
Dabiri D, Gharib M (2001) Simultaneous free-surface deformation and near-surface velocity measurements. Exp Fluids 30:381–390
Gharib M (1994) Some aspects of near surface vortices. Appl Mech Rev 47:157–162
Gharib M, Weigand A (1996) Experimental studies of vortex disconnection and connection at a free surface. J Fluid Mech 321:59–86
Ghiglia DC, Pritt MD (1998) Two-dimensional phase unwrapping: theory, algorithms and software. Wiley, New York
Grant I, Stewart N, Padilla-Perez IA (1990) Topographical measurements of water waves using the projection moire method. Appl Opt 29:3981–3983
Maurel A, Cobelli P, Pagneux V, Petitjeans P (2009) Experimental and theoretical inspection of the phase-to-height relation in Fourier transform profilometry. Appl Opt 48(2):380–392. doi:10.1364/AO.48.000380
Moisy F, Rabaud M, Salsac K (2008) Measurement by digital image correlation of the topography of a liquid surface. Exp Fluids (submitted)
Patorski K (1993) Handbook of the Moire fringe technique. Elsevier, Amsterdam
Rajoub BA, Lalor MJ, Burton DR, Karout SA (2007) A new model for measuring object shape using non-collimated fringe-pattern projections. J Opt A Pure Appl Opt 9:66. doi:10.1088/1464-4258/9/6/S10
Ruban VP (2000) Interaction of a vortex ring with the free surface of an ideal fluid. Phys Rev E 62:4950–4958. doi:10.1103/PhysRevE.62.4950
Savelsberg R, van de Water W (2008) Turbulence of a free surface. Phys Rev Lett 100(3):034501. doi:10.1103/PhysRevLett.100.034501
Savelsberg R, Holten A, van de Water W (2006) Measurement of the gradient field of a turbulent free surface. Exp Fluids 41:629–640. doi:10.1007/s00348-006-0186-x
Su X, Chen W (2001) Fourier transform profilometry: a review. Opt Lasers Eng 35:263–284
Su X, Chen W (2004) Reliability-guided phase unwrapping algorithm: a review. Opt Lasers Eng 42:245–261
Takeda M, Mutoh K (1983) Fourier transform profilometry for the automatic measurement of 3-D object shapes. Appl Opt 22:3977–3982
Takeda M, Ina H, Kobayashi S (1982) Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry. J Opt Soc Am (1917–1983) 72:156
Tsubaki R, Fujita I (2005) Stereoscopic measurement of a fluctuating free surface with discontinuities. Meas Sci Technol 16:1894–1902. doi:10.1088/0957-0233/16/10/003
Umeki M, Lund F (1997) Spirals and dislocations in wave–vortex systems. Fluid Dyn Res 21:201–210
Vivanco F, Melo F (2000) Surface spiral waves in a filamentary vortex. Phys Rev Lett 85:2116–2119. doi:10.1103/PhysRevLett.85.2116
Vivanco F, Melo F (2004) Experimental study of surface waves scattering by a single vortex and a vortex dipole. Phys Rev E 69(2):026307. doi:10.1103/PhysRevE.69.026307
Walker DT, Chen C-Y, Willmarth WW (2006) Turbulent structure in free-surface jet flows. J Fluid Mech 91:223. doi:10.1017/S0022112095002680
Wright WB, Budakian R, Putterman SJ (1996) Diffusing light photography of fully developed isotropic ripple turbulence. Phys Rev Lett 76:4528–4531. doi:10.1103/PhysRevLett.76.4528
Wright WB, Budakian R, Pine DJ, Putterman SJ (1997) Imaging of Intermittency in ripple-wave turbulence. Science 278:1609
Zappa E, Busca G (2008) Comparison of eight unwrapping algorithms applied to Fourier-transform profilometry. Opt Lasers Eng 46:106–116
Zhang X (1996) An algorithm for calculating water surface elevations from surface gradient image data. Exp Fluids 21:43–48
Zhang X, Cox CS (1994) Measuring the two-dimensional structure of a wavy water surface optically: a surface gradient detector. Exp Fluids 17:225–237. doi:10.1007/BF00203041
Zhang Q-C, Su X-Y (2002) An optical measurement of vortex shape at a free surface. Opt Laser Technol 34:107–113
Zhang X, Dabiri D, Gharib M (1994) A novel technique for free-surface elevation mapping. Phys Fluids 6(9):S11–S11
Zhang X, Dabiri D, Gharib M (1996) Optical mapping of fluid density interfaces: concepts and implementations. Rev Sci Instrum 67:1858–1868
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Cobelli, P.J., Maurel, A., Pagneux, V. et al. Global measurement of water waves by Fourier transform profilometry. Exp Fluids 46, 1037–1047 (2009). https://doi.org/10.1007/s00348-009-0611-z
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DOI: https://doi.org/10.1007/s00348-009-0611-z