Virtual transducer model

For more info about our services contact : help@bestpfe.com

Table of contents

Chapter 1. Introduction
I. FOCALISATION DANS DES MILIEUS HOMOGENES ET HETEROGENES
I.A. Focalisation en milieu homogène
I.B Focalisation en milieu heterogene
II. METHODES D’ESTIMATION DE FONCTIONS DE GREEN
II.A Methode reposant sur le modèle écran en champ-proche (estimation de loi de retards seulement)
II.B. Methodes estimant la fonction de Green complète
III. MODELES POUR LES SIGNAUX
III.A Formule de Rayleigh-Sommerfeld
III.A.2 Approximation de Fresnel en coordonnes cartésiennes
III.A.3 Approximation de Fresnel en coordonnées polaires
III.D La propagation comme un filtre passe-bas
IV. PLAN DE LA THESE
Chapter 2. Le Retournement Temporel a partir de Transducteurs Virtuels: FDORT
II. INTRODUCTION AND PRESENTATION OF THE METHOD
III. THE DORT METHOD BETWEEN TWO DIFFERENT ARRAYS
II.A. The transfer matrix and the time reversal operator
II.B. Case of isotropic, pointlike scatterers and single scattering
IV. FOCUSED BEAMS AND VIRTUAL TRANSDUCERS
III.A. Virtual transducer model
III.B. The DORT method between a real array and a virtual array
III.C. The focused transmits as an orthogonal basis
III.D Link to back-propagation
V. APPLICATION TO FOCUSING THROUGH A FAR-FIELD PHASE SCREEN.69
IV.A Changing a far-field phase screen problem into a near-field phase screen problem using a virtual array
IV.B Steering from the virtual array
IV.C Practical implementation
VI. FDORT WITH TIME GATING
V.A. Influence of noise on eigenvectors and eigenvalues
V.B. A solution: FDORT with time gating
VII. LOCAL FDORT
VI.A. FDORT in a limited region of space
VI.B Application to moving scatterers
VI.C. Application to small objects detection
VIII. CONCLUSION
REFERENCES
Chapter 3. Objets Etendus
I. INTRODUCTION
II. THEORY
II.A Expression of the time reversal operator for an extended object
II.B Invariants of the Time Reversal Operator: The Prolate Spheroidal functions
III. RESULTS
III.A. Results with a one-dimensional array
III.B Application to Green’s function estimation and focusing
III.B Results with a 2D array
IV. COMPARISON WITH PREVIOUS WORK
V. APPLICATIONS: SUPER-RESOLUTION, TOMOGRAPHY AND MICROCALCIFICATION DIAGNOSIS
VI. CONCLUSION
APPENDIX A: DERIVATION OF THE KERNEL
APPENDIX B: LARGER OBJECTS
APPENDIX C: INVARIANTS FOR 3D OBJECTS WITH 2D ARRAYS
DORT with a 2D array
Analytical solutions for separable kernels
Chapter 4. FDORT dans le Speckle
I. INTRODUCTION
II. BASIC STATISTICAL PROPERTIES OF SPECKLE SIGNALS
A. Randomness of the speckle
B. First order statistics
C. Second order statistics
D. Basics of estimation theory
III. INTERPRETATIONS OF KKH
A. Spatial correlation matrix, or Van Cittert Zernike matrix
B. Time Reversal Operator for an equivalent virtual object
C. Variance and standard deviation of the estimation
D. Interpretation of the first eigenvalue in speckle
IV. APPLICATION TO FOCUSING IN HETEROGENEOUS MEDIUM
A. Equivalent virtual object and iteration of the method
B. Focusing through a far-field phase screen
C. Medical phantom results
V. LINK WITH OTHER ABERRATION CORRECTION METHOD IN SPECKLE.202
A. 1-lag cross-correlation (O’Donnell)
B. Maximum Speckle Brightness
C. Eigenfunction analysis of backscattering signal
D. Multi-lag cross-correlation (LMS algorithm)
VI. GREEN FUNCTION ESTIMATION AND FOCUSING IN PRESENCE OF STRONG INTERFERING SIGNALS
VII. CONCLUSION
APPENDIX A COHERENT INTENSITY AND FOCUSING CRITERION IN FUNCTION OF THE SPATIAL CORRELATION FUNCTION
Appendix B. VARIANCE OF THE ESTIMATION
A. Variance of the amplitude of the spatial correlation coefficients
B. Variance of the phase
Chapter 5. Signaux bandes larges: Invariants spatio-temporel du Retournement Temporel
I. INTRODUCTION
II. SPATIO-TEMPORAL INVARIANTS OF THE TIME REVERSAL
II.A Heuristics
II.B The Time Reversal Operator in the Time Domain
II.C. Decomposition of the Tensor
II.D. Practical implementation and results
III. DECOMPOSITION OF THE FOCUSED TENSOR
III.A The Focused Tensor
III.B Decomposition of the Focused Tensor
III.C. Results
IV. RECONSTRUCTION OF THE TEMPORAL GREEN’S FUNCTION BY CORRELATION OF MONOCHROMATIC GREEN’S FUNCTIONS
IV.1 Theory
IV.2 Experiments
V.CONCLUSION
REFERENCES