Application of Two Dimensional Wavelet Transform to the Visualization of Glass Fibers in a Turbulent Flame
In different manufacturing processes, glass fibers are drawn out in a turbulent flame. Our purpose is to determine the 3-D trajectory of fibers whose diameter lies in the range [10–30 μm]. The sample volume can be visualized by using techniques such as high-speed in-line holography.1 Then, the reconstructed field is analysed in our laboratory by a CCD camera linked to an image digitizer. A 3-D translation of the holographic plate allows the focusing on each fiber element to be updated. This is tedious work. When the reconstructed images are constrated enough, automated following of the trajectories facilitates human based analysis.2 Numerous works have been published concerning the automation of the reconstruction step for particle holograms.3–5 However, the random spatial distributions of temperature induce a strong local variation of the refractive index. Consequently, the holographic images are altered and the focusing step of the automatic reconstruction is not very reliable. Other methods which eliminate the need for focusing mustrtherefore be envisaged.
KeywordsWavelet Transform Turbulent Flame Fiber Element Holographic Image Optical Transfer Function
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