Preface |
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xi | |
1 Introduction and overview of the book |
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1 | (16) |
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1.1 Why passive, correlation-based imaging? |
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1 | (9) |
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1.1.1 Travel time estimation |
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2 | (1) |
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1.1.2 Applications of travel time estimation |
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3 | (1) |
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4 | (2) |
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1.1.4 Auxiliary array or virtual source imaging |
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6 | (2) |
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1.1.5 Passive synthetic aperture imaging |
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8 | (1) |
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1.1.6 Imaging with intensity cross correlations |
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9 | (1) |
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1.2 Chapter-by-chapter description of the book |
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10 | (7) |
2 Green's function estimation from noise cross correlations |
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17 | (34) |
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2.1 The scalar wave equation and its Green's function |
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17 | (8) |
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2.1.1 The Sommerfeld radiation condition |
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19 | (1) |
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20 | (1) |
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2.1.3 The Helmholtz-Kirchhoff identity |
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21 | (2) |
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2.1.4 Application to time reversal |
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23 | (2) |
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2.2 The scalar wave equation with noise sources |
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25 | (4) |
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2.3 Green's function estimation with a uniform distribution of sources in a homogeneous open medium |
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29 | (2) |
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2.4 Green's function estimation with an extended distribution of sources in an inhomogeneous open medium |
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31 | (3) |
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2.5 Green's function estimation with an extended distribution of sources in an inhomogeneous cavity |
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34 | (4) |
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2.6 Green's function estimation with a limited distribution of sources in a one-dimensional inhomogeneous medium |
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38 | (10) |
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2.6.1 The one-dimensional wave equation |
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39 | (4) |
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2.6.2 Reflection seismology |
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43 | (2) |
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45 | (3) |
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48 | (1) |
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2.A Appendix: the covariance of the empirical cross correlation |
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48 | (3) |
3 Travel time estimation from noise cross correlations using stationary phase |
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51 | (17) |
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3.1 High-frequency wave propagation |
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52 | (1) |
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3.2 High-frequency asymptotic analysis of the Green's function in a homogeneous medium |
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53 | (1) |
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3.3 High-frequency asymptotic analysis of the Green's function in a smoothly varying medium |
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53 | (7) |
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3.3.1 An introduction to geometrical optics |
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53 | (2) |
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3.3.2 Ray solution of the eikonal equation |
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55 | (2) |
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3.3.3 Fermat's principle for the travel time |
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57 | (1) |
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3.3.4 Properties of the travel time |
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58 | (2) |
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3.4 High-frequency asymptotic analysis of the cross correlation |
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60 | (7) |
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67 | (1) |
4 Overview of conventional sensor array imaging |
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68 | (26) |
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4.1 Passive array imaging of sources |
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68 | (6) |
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68 | (1) |
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69 | (1) |
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4.1.3 The linear forward operator |
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69 | (1) |
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4.1.4 The adjoint operator |
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70 | (1) |
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4.1.5 Least squares inversion |
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71 | (2) |
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4.1.6 The reverse-time imaging function |
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73 | (1) |
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4.1.7 Kirchhoff migration (or travel-time migration) |
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74 | (1) |
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4.2 Passive array imaging of sources: resolution analysis |
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74 | (10) |
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4.2.1 Full-aperture array |
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75 | (1) |
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4.2.2 Partial-aperture array |
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75 | (8) |
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4.2.3 Summary of resolution analysis for passive source imaging |
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83 | (1) |
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4.3 Active array imaging of reflectors |
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84 | (8) |
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84 | (1) |
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4.3.2 Source and reflector array imaging: comparison |
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85 | (1) |
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85 | (1) |
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4.3.4 Nonlinear inversion |
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86 | (1) |
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4.3.5 Linearization of the forward problem |
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86 | (2) |
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4.3.6 Linearized inversion |
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88 | (1) |
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4.3.7 The reverse-time imaging function |
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89 | (2) |
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4.3.8 Kirchhoff migration (or travel-time migration) |
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91 | (1) |
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4.3.9 Summary of resolution analysis for active reflector imaging |
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91 | (1) |
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4.4 A remark about time-reversal experiments |
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92 | (1) |
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92 | (2) |
5 Passive array imaging of reflectors using ambient noise illumination |
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94 | (12) |
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5.1 Imaging configurations of noise sources, sensors, and reflectors |
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94 | (2) |
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5.2 Stationary phase analysis of the cross correlation with reflectors |
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96 | (3) |
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5.3 Migration imaging of cross correlations |
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99 | (6) |
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5.3.1 Migration imaging with daylight illumination |
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100 | (1) |
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5.3.2 Migration imaging with backlight illumination |
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101 | (2) |
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5.3.3 Migration imaging with surround light illumination |
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103 | (2) |
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105 | (1) |
6 Resolution analysis for passive array imaging using ambient noise illumination |
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106 | (30) |
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6.1 A comparison of reflector imaging with active and passive arrays |
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107 | (1) |
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6.2 Imaging by cross correlation of signals generated by ambient noise sources |
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108 | (3) |
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6.2.1 The wave equation with noise sources |
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108 | (1) |
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6.2.2 Statistical stability of the cross correlation function |
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108 | (1) |
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6.2.3 Passive sensor imaging |
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109 | (1) |
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6.2.4 Hypothesis of small decoherence time and correlation radius for the noise sources |
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110 | (1) |
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6.3 Structure of the cross correlations in a homogeneous medium |
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111 | (4) |
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6.3.1 The background Green's function |
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111 | (1) |
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6.3.2 The peaks of the cross correlation in the presence of a reflector |
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111 | (4) |
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6.4 Resolution analysis of correlation-based imaging |
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115 | (11) |
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6.4.1 The daylight imaging function |
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115 | (7) |
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6.4.2 The backlight imaging function |
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122 | (2) |
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6.4.3 Numerical simulations |
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124 | (1) |
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6.4.4 Role of illumination diversity |
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125 | (1) |
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126 | (1) |
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6.A Appendix: Proof of Proposition 6.2 |
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126 | (2) |
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6.B Appendix: Proof of Propositions 6.4-6.5 |
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128 | (4) |
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6.C Appendix: Proof of Proposition 6.6 |
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132 | (4) |
7 Travel time estimation using ambient noise in weakly scattering media |
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136 | (16) |
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7.1 Role of scattering in travel time estimation with cross correlations |
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136 | (2) |
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7.2 A model for the scattering medium |
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138 | (2) |
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7.3 Signal-to-noise ratio reduction and enhanced resolution due to scattering |
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140 | (2) |
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7.4 Use of fourth-order cross correlations |
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142 | (3) |
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145 | (1) |
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7.A Appendix: Complete expression of the average cross correlation |
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146 | (2) |
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7.B Appendix: Proof of Proposition 7.1 |
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148 | (1) |
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7.C Appendix: Proof of Proposition 7.2 |
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149 | (3) |
8 Correlation-based reflector imaging using ambient noise in weakly scattering media |
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152 | (35) |
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8.1 Role of scattering in correlation-based imaging |
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152 | (2) |
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8.2 Passive sensor imaging in a randomly scattering medium |
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154 | (11) |
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8.2.1 A model for the scattering medium |
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155 | (1) |
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8.2.2 The differential cross correlation |
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156 | (1) |
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8.2.3 Expansion of the clutter Green's function |
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157 | (2) |
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8.2.4 Expansion of the differential cross correlation |
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159 | (1) |
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8.2.5 Statistical analysis of the differential cross correlation |
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160 | (4) |
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8.2.6 On the trade-off between resolution enhancement and signal-to-noise ratio reduction |
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164 | (1) |
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8.2.7 Numerical simulation of migration imaging with cross correlations in the presence of scatterers |
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164 | (1) |
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8.3 Passive sensor imaging with a reflecting interface |
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165 | (5) |
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8.3.1 Stationary phase analysis of the cross correlation with a reflecting interface |
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166 | (2) |
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8.3.2 Numerical simulations of migration imaging with cross correlations in the presence of an interface |
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168 | (2) |
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8.4 Iterated cross correlations for passive imaging in a randomly scattering medium |
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170 | (2) |
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8.4.1 The coda cross correlation |
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170 | (2) |
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8.4.2 Numerical simulations of migration imaging with coda cross correlations |
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172 | (1) |
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172 | (2) |
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8.A Appendix: Proof of Proposition 8.1 |
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174 | (4) |
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8.B Appendix: Proof of Proposition 8.2 |
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178 | (4) |
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178 | (2) |
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180 | (2) |
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8.C Appendix: Statistical analysis of the cross correlations |
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182 | (3) |
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8.C.1 The cross correlation at the difference of travel times |
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182 | (2) |
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8.C.2 The cross correlation at the sum of travel times |
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184 | (1) |
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8.D Appendix: Proof of Proposition 8.3 |
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185 | (2) |
9 Virtual source imaging in homogeneous media |
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187 | (19) |
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9.1 Introduction to virtual source imaging |
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187 | (3) |
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9.2 Ideal virtual source imaging with an infinite source array |
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190 | (1) |
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9.3 High-frequency analysis in a homogeneous background with a limited source array |
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191 | (6) |
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9.3.1 Direct scattering problem |
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191 | (1) |
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9.3.2 High-frequency analysis of the cross correlations |
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192 | (3) |
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9.3.3 High-frequency analysis of the imaging function |
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195 | (2) |
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9.4 Passive synthetic aperture imaging in a homogeneous background |
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197 | (4) |
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9.4.1 High-frequency analysis of the imaging function |
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198 | (1) |
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9.4.2 Comparison with classical synthetic aperture imaging |
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199 | (2) |
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201 | (1) |
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9.A Appendix: Proof of Proposition 9.2 |
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202 | (1) |
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9.B Appendix: Proof of Proposition 9.3 |
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203 | (3) |
10 Vitual source imaging in scattering media |
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206 | (22) |
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10.1 The auxiliary array imaging setup |
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206 | (2) |
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10.2 Time-reversal interpretation of virtual source imaging |
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208 | (1) |
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10.3 The paraxial approximation in random media |
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209 | (3) |
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10.3.1 The main results in the paraxial approximation |
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210 | (1) |
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10.3.2 Validity of the paraxial approximation in random media |
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211 | (1) |
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10.4 Analysis of virtual source imaging in the random paraxial regime |
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212 | (6) |
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10.4.1 The cross correlation of the recorded field |
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212 | (4) |
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10.4.2 Migration of cross correlations |
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216 | (2) |
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10.5 Numerical simulations |
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218 | (1) |
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10.6 Passive synthetic aperture imaging in random media |
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219 | (3) |
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222 | (1) |
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10.A Appendix: Proofs of Propositions 10.1-10.2 |
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223 | (4) |
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10.B Appendix: Proofs of Propositions 10.3-10.4 |
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227 | (1) |
11 Imaging with intensity cross correlations |
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228 | (17) |
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11.1 The ghost imaging setup |
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228 | (3) |
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11.2 The intensity correlation function |
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231 | (6) |
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11.2.1 The empirical and statistical correlations |
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231 | (2) |
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233 | (2) |
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11.2.3 Time-reversal interpretation |
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235 | (1) |
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11.2.4 Averaging with respect to the random medium |
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236 | (1) |
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237 | (5) |
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11.3.1 Resolution analysis for the fully incoherent case |
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237 | (3) |
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11.3.2 Resolution analysis for the partially coherent case |
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240 | (2) |
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242 | (1) |
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11.A Appendix: The fields in the white-noise paraxial regime |
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243 | (2) |
12 A review of wave propagation in random media |
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245 | (24) |
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12.1 The random travel time model |
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245 | (8) |
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12.1.1 Domain of validity |
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245 | (2) |
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12.1.2 Statistics of the amplitude and phase perturbations |
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247 | (3) |
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12.1.3 The moments of the Green's function |
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250 | (3) |
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12.2 The random paraxial model |
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253 | (5) |
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12.2.1 The random paraxial regime |
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253 | (1) |
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12.2.2 The random paraxial wave equation |
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254 | (1) |
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12.2.3 The moments of the fundamental solution |
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255 | (3) |
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12.3 The randomly layered model |
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258 | (4) |
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12.3.1 The scaling regime |
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258 | (2) |
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12.3.2 Review of wave propagation in randomly layered media |
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260 | (1) |
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12.3.3 Statistics of the Green's function |
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261 | (1) |
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262 | (1) |
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12.A Appendix: Proof of Lemma 12.1 |
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262 | (2) |
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12.B Appendix: Proof of Proposition 12.6 |
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264 | (3) |
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12.C Appendix: Proof of Proposition 12.8 |
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267 | (2) |
13 Appendix: Basic facts from analysis and probability |
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269 | (16) |
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269 | (1) |
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270 | (1) |
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13.3 Stationary phase method |
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270 | (2) |
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272 | (2) |
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274 | (11) |
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274 | (1) |
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275 | (1) |
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13.5.3 Gaussian random vectors |
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276 | (1) |
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277 | (1) |
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278 | (1) |
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13.5.6 Mean square theory |
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279 | (2) |
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13.5.7 Gaussian processes |
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281 | (1) |
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13.5.8 Stationary Gaussian processes |
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282 | (1) |
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13.5.9 Vector- and complex-valued Gaussian processes |
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283 | (2) |
References |
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285 | (8) |
Index |
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293 | |