Hologram reconstruction by use of optical wavelet transform

High-speed in-line holography is used to visualize the trajectories of glas s fibers being drawn out in a turbulent flame. To improve the signal-to-noi se ratio, the images are not observed by a conventional reconstruction setu p, but the holographic plate is placed directly on the input plane of a wav elet-transform optical system. This processing system is based on a VanderL ugt correlator with inclusion of an electrically addressed spatial light mo dulator. The shape of the matched filters is deduced by successive rotation and dilatation operations of wavelet functions in the Fourier domain. We e stimate the three-dimensional location of a fiber element and its orientati on by searching for the daughter wavelet that yields the maximum intensity on the output plane of the correlator, which also contains the reconstructe d image. The results are compared with those obtained by conventional optic al reconstruction. The signal-to-noise ratios of the images observed on the output plane are improved. Moreover, it is shown that the axis coordinate accuracy is improved to Delta z = +/-50 mu m, instead of +/-0.5 mm for holo graphic reconstruction. (C) 1999 Optical Society of America. OCIS codes: 070.0070, 090.0090, 070.5010, 100.4550, 100.7410, 230.6120.