Inspection des materiaux, recontruction 3d et traitement numerique d'images en tomographie neutronique

Abstract

The objective of this thesis is the presentation, the study and application of 2D or 3D image reconstruction by Neutron Transmission Tomography. Neutron Tomography has known a very fast growth as much as X-rays tomography from the discovery of the relation between Radon and Fourier transforms passing by the establishment of the Filtered Back Projection algorithm until nowadays. In this thesis, fist of all are presented the theory and practice of projection and reconstruction processes. As a second phase, Neutron Tomography facilities that we have worked with or on were presented. Neutron transmission experiments were performed on different kind of materials in order to measure the neutron attenuation, surface density of absorbing element and to make in evidence the beam hardening effect. The last phase was reserved to the theoretical and experimental analysis of projection data errors and noise and their influence on reconstructed image quality. Some solutions for errors aliasing and noise reducing were proposed.