New Arrangements for Fresnel Focusing

  • Bruno Richard
  • Mathias Fink
  • Pierre Alais
Part of the Acoustical Imaging book series (ACIM, volume 9)


Medical results of a 2 state Fresnel focusing, presented at the 7th International Symposium on Acoustical Imaging [1] , 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 [2].


Focal Distance Beam Pattern Small Aperture Large Aperture Fresnel Zone 
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  1. 1.
    P. Alais and M. Fink, “Fresnel zone focusing of linear arrays applied to B and C echography”, Acoustical Holography, vol 7, 1977, p. 509–522.Google Scholar
  2. 2.
    P. Alais and B. Richard, “Progress in Fresnel imaging, clinical evaluation”, Acoustical Imaging, Vol. 8, 1978Google Scholar
  3. 3.
    M. Fink, “Theoretical aspects of the Fresnel focusing technique”, Acoustical Imaging, Vol. 8, 1978.Google Scholar
  4. 4.
    M. Fink and M.T. Larmande, “Wideband Fresnel focusing array response”. Proceedings of the IEEE ultrasonic symposium, New Orleans, Sept. 1979.Google Scholar

Copyright information

© Plenum Press, New York 1980

Authors and Affiliations

  • Bruno Richard
    • 1
  • Mathias Fink
    • 2
  • Pierre Alais
    • 2
  1. 1.Service de BiophysiqueCHU CochinParisFrance
  2. 2.Laboratoire de Mécanique PhysiqueUniversité Pierre et Marie CurieParisFrance

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