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Proceedings Paper

Natural pixel decomposition for interferometric tomography
Author(s): Don J. Cha; Soyoung Stephen Cha
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Paper Abstract

Interferometric reconstruction of three-dimensional flow fields, that is, interferometric tomography, can be a very useful flow diagnostic tool in many engineering applications. It is noninvasive and can capture gross fields; however, it frequently confronts a challenging problem of reconstructing flow fields from insufficient data. In most cases, flow-field interferometric data are sparse, nonuniform, noisy, and incomplete in projection and scanning due to opaque objects present either inside or outside the field. Recently, we have developed and tested a new approach in an effort to improve reconstruction under these ill-posed conditions. In essence, the method incorporates distinct features of flow field data, being based on natural pixel decomposition of the field to be reconstructed. It employs rectangular grid elements of different sizes and aspect ratios. It thus reflects intrinsic spatial resolution information contained in the measured data, and allows reconstruction with better resolution and accuracy in the region with more probing rays scanned. It also can efficiently utilize a priori information on the field. Computer simulation of experiments involving a flow field has demonstrated the superiority of the developed method to the conventional fixed grid method. In simulation, the temperature field of a three-dimensional gravity-driven flow of two interacting cubic heat sources, which is produced from a numerical code, is tested. Both of the maximum and average reconstruction errors are reduced appreciably. Especially, the reconstruction demonstrates substantial improvement in the region of interest. Currently, an experiment for verifying the developed interferometric tomographic technique as well as the three-dimensional numerical heat transfer code is under way.

Paper Details

Date Published: 1 December 1991
Proc. SPIE 1554, Second International Conference on Photomechanics and Speckle Metrology, (1 December 1991); doi: 10.1117/12.57446
Show Author Affiliations
Don J. Cha, Univ. of Illinois/Chicago (United States)
Soyoung Stephen Cha, Univ. of Illinois/Chicago (United States)

Published in SPIE Proceedings Vol. 1554:
Second International Conference on Photomechanics and Speckle Metrology
Fu-Pen Chiang; Fu-Pen Chiang, Editor(s)

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