| 摘要 |
The proposed holographic particle image velocimetry (HPIV) system employs holograms of two time-separated particle fields, illuminated by separate reference beams (606, 608) on a single recording medium (624). 90-degree scattering is utilized for the object wave, in order to improve N.A. and resolve the third dimension of the hologram. The proposed HPIV system then uses substantially the same optical geometry for the reconstruction process. A CCD camera (702) is utilized to extract particle subimages, thin slice by thin slice, and a standard centroid-finding algorithm is applied to extract centroid locations for each volume. The concise cross correlation (CCC) algorithm for extracting velocity vector fields from the centroid data is an important enabling feature of the proposed system. Correlations are calculated between subsets of centroids representing the images or cubes, and velocity vectors are computed from the individual correlations. Higher spatial resolution can also be obtained by pairing particle centroids individually.
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