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4. Focusing systems
4.1 Focusing lens
The basis of the acoustic microscope remains the acoustic lens, which must be carefully cut to ensure the best possible image quality. A piezoelectric transducer provides electromechanical signal conversion, using a thin layer of zinc oxide (ZnO), a few µm thick, with a perfectly controlled crystallographic orientation, deposited on one of the flat, polished faces of a small, metallized synthetic sapphire rod. The power efficiency of such a transducer can reach 50% for frequencies in the gigahertz range.
The high attenuation in the transmission fluid means that lens curvature radii of the order of a tenth of a millimetre are required. The manufacture of spherical surfaces of this size, polished to an optical quality, is a tricky business,...
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Focusing systems
Bibliography
Directory
Organizations – Associations – Federations
University of Montpellier II. Laboratoire d'Analyse des Interfaces et de nanophysique.
Institut supérieur de l'électronique et du numérique (ISEN) – Université Lille I – Sciences et technologies – Université de Valenciennes et du Hainaut-Cambresis
Parametric Imaging Laboratory. Université Pierre et Marie Curie – Paris 6...
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