Role of scattering in virtual source array imaging (Q2876839)

The authors consider imaging in a scattering medium, where the illumination goes through this medium and near the object to be imaged there is an auxiliary passive receiver array. Instead of imaging directly with the source-receiver array on the far side of the object, the authors use imaging based on the data of the passive array on the near side of the object. The imaging is done with travel time migration using the cross correlations of the passive array data. They showed in their earlier paper [Inverse Probl. 28, No. 7, Article ID 075002, 38 p. (2012; Zbl 1260.65090)] that under some assumptions (the source array is infinite, the scattering medium is a randomly isotropic medium or a randomly layered medium, the medium between the auxiliary array and the object to be imaged is homogeneous), imaging with cross correlations completely eliminates the effect of random medium. In this paper, the problem of resolution of the obtained image is analysed in the case when both the source array and the passive receiver array are finite. They show that the resolution of the image can be inhanced for the case of isotropic random media because the random medium can increase the diversity of illumination. The analysis carried out is based on the asymptotic expressions of the moments of some Green's function. The insight in the context of imaging, presented in the paper, is new. It should be added that in geophysics, imaging with cross correlations of the auxiliary array is very effective and produces images that are nearly as good as in a homogeneous medium.