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Synthèse d'émission spatio-temporelle pour l'imagerie acoustique

Abstract : Finding a compromise between frame rate and image quality is a major issue in the definition of new coherent imaging methods. The objective of this thesis is to propose new imaging mode taking most benefit from hardware platforms. The applications are ultrasonic imaging and underwater acoustics. The manuscript first proposes a formal framework to the problem of frame rate versus contrast compromise and demonstrates the optimality of synthetic aperture methods. The equivalence, in terms of contrast and resolution, between synthetic aperture and focus imaging is then established. The problem of signal to noise ratio is solved by the use of transmission matrix maximizing the acoustic energy (Hadamard matrix). We introduced a new method, called "synthesis reduction", allowing a significant improvement of the frame rate. For this, we search the optimum matrix in terms of maximizing transmission beams energy on the imaging area. This optimum is a matrix composed of prolate spheroidal sequences. Then we introduced the "Spheroidal Synthetic Aperture" that exploits the properties of the matrix and moves the frame rate versus contrast compromise in a frame rate versus image size compromise. The last part of this manuscript is devoted to the measurement and correction of the platform motions by micronavigation methods. The results of this work are subject of experimental validation on a programmable 128-channel ultrasound scanner and a synthetic aperture sonar.
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Contributor : Frédéric Mosca Connect in order to contact the contributor
Submitted on : Monday, March 7, 2011 - 7:13:50 PM
Last modification on : Friday, July 31, 2020 - 10:44:07 AM
Long-term archiving on: : Thursday, March 30, 2017 - 8:03:50 AM


  • HAL Id : pastel-00574356, version 1



Frédéric Mosca. Synthèse d'émission spatio-temporelle pour l'imagerie acoustique. Traitement du signal et de l'image [eess.SP]. Télécom ParisTech, 2010. Français. ⟨pastel-00574356⟩



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