Quantitative flow visualization in supersonic jets through tomographic inversion of wavefronts estimated through shadow casting.
We present a simple method with which to reconstruct wavefronts that are transilluminating supersonic jets through measurement of their local slopes. The wavefront slopes are measured in two orthogonal directions by use of the average displacements suffered by a random-dot pattern in its shadow cast by the wavefront in front of it. A smooth wavefront is estimated from its measured slopes by a least-squares curve fitting technique. The calculated wavefront distortion is tomographically inverted to yield the density distributions of the object. The results are comparable to that obtained by use of a phase-retrieval algorithm from axial intensity transport measurements.
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