New Arrangements for Fresnel Focusing
Medical results of a 2 state Fresnel focusing, presented at the 7th International Symposium on Acoustical Imaging  , proved that a very good lateral resolution (1.5 mm) was obtained in vivo due to the use of a large aperture. The need for very low sidelobe levels in medical imaging had led us to associate to a Fresnel lens at reception a non focused transmission. Far off-axis sidelobes are then reduced (−40 dB) at the expense of the lateral resolution which is multiplied by 1.5. This apodizing technique gave good results for medical diagnosis .
KeywordsFocal Distance Beam Pattern Small Aperture Large Aperture Fresnel Zone
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