Abstract
Optical tomography is applied to the speckle photographic measurement of an asymmetric flow field with variable fluid density. The convolution back projection algorithm is used for obtaining the 3-D density distribution. Noise in the experimental data is reduced by spline smoothing. The method is verified with a steady, laminar, axisymmetric helium jet exhausting vertically into the ambient air, and then applied to a non-axisymmetric helium jet for determining the helium concentration. It is found that speckle photographic recordings are very adequate for tomographic reconstruction, because they provide a high number of data points from each projection. The influence of the limited number of projections on the reconstruction quality is particularly investigated.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Blinkov, G. N.; Fomin, N. A.; Soloukhin, R. I. 1987: Multidirection speckle photography of density gradients in a flame. Paper presented at 11th Int. Coll. on Gasdynamics of Explosions and Reactive Systems, Warszawa, Poland
Debrus, S.; Françon, M.; Grover, C. P.; May, M.; Roblin, M. L. 1972: Ground glass differential interferometer. Appl. Opt. 11, 853–857
Erbeck, R.; Keller, J. 1987: Image processing of Young's fringes in laser speckle velocimetry. In: The use of computers in laser velocimetry (eds. Pfeifer, H. J.; Jaeggy, B.) pp. 26/1–26/5. St. Louis, France: ISL
Faris, G. W.; Byer, R. L. 1987: Beam-deflection optical tomography. Opt. Lett. 12, 72–74
Herman, G. T. 1980: Image reconstruction from projections. New York: Academic Press
Hesselink, L. 1989: Optical tomography. In: Handbook of flow visualization (ed. Yang, W.-J.). Washington/DC: Hemisphere
Köpf, U. 1972: Application of speckling for measuring the deflection of laser light by phase objects. Opt. Commun. 5, 347–350
Merzkirch, W. 1987: Flow visualization, 2nd edn. New York: Academic Press
Snyder, R.; Hesselink, L. 1984: Optical tomography for flow visualization of the density field around a revolving helicopter rotor blade. Appl. Opt. 23, 3650–3656
Sweeney, D. W.; Vest, C. W. 1973: Reconstruction of three-dimensional refractive index fields from multi-directional interferometric data. Appl. Opt. 22, 2649–2664
Wernekinck, U.; Merzkirch, W. 1987: Speckle photography of spatially extended refractive-index fields. Appl. Opt. 26, 31–32
Author information
Authors and Affiliations
Additional information
Dedicated to Professor Dr.-Ing. J. Zierep on the occasion of his 60th birthday
Rights and permissions
About this article
Cite this article
Liu, T.C., Merzkirch, W. & Oberste-Lehn, K. Optical tomography applied to speckle photographic measurement of asymmetric flows with variable density. Experiments in Fluids 7, 157–163 (1988). https://doi.org/10.1007/BF02332980
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02332980