Hologram reconstruction using liquid crystal spatial light modulators

摘要

Abstract: High-speed in-line holography is used to visualize the trajectories fibers which are drawn out in a turbulent flame. In order to improve the SNR, the images are not observed by a conventional reconstruction setup. In our case, the holographic plate is directly placed on the input plane of a wavelet-transform optical system. This processing system is based on a VanderLugt correlator including an Electrically Addressed Spatial Light Modulator (EASLM). The shape of matched filters is deduced by successive rotation and dilatation operations of wavelet functions in the Fourier domain. The 3-D location of a fiber element and its orientation are estimated by searching the daughter wavelet which yields the maximum intensity on the output plane of the correlator, which also contains the reconstructed image. The results are compared with those obtained by a conventional optical reconstruction. The SNR of the images observed on the output plane is improved. Moreover, it is shown that the axis coordinate accuracy is improved to $Delta@z equals plus or minus 50 micrometer, instead of plus or minus 0,5 mm for holographic reconstruction. !14