We present a physically intuitive matrix approach for wave imaging and characterization in scattering media. The experimental proof of concept is performed with ultrasonic waves, but this approach can be applied to any field of wave physics for which multielement technology is available. The concept is that focused beam forming enables the synthesis, in transmit and receive, of an array of virtual transducers which map the entire medium to be imaged. The interelement responses of this virtual array form a focused reflection matrix from which spatial maps of various characteristics of the propagating wave can be retrieved. Here we demonstrate (i) a local focusing criterion that enables the image quality and the wave velocity to be evaluated everywhere inside the medium, including in random speckle, and (ii) a highly resolved spatial mapping of the prevalence of multiple scattering, which constitutes a new and unique contrast for ultrasonic imaging. The approach is demonstrated for a controllable phantom system and for in vivo imaging of the human abdomen. More generally, this matrix approach opens an original and powerful route for quantitative imaging in wave physics.

中文翻译：

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散射介质定量成像的反射矩阵方法

我们提出了一种物理直观的矩阵方法，用于散射介质中的波成像和表征。实验的概念证明是使用超声波进行的，但是这种方法可以应用于具有多元素技术的任何波物理领域。该概念是，聚焦束形成使得能够在发射和接收中合成虚拟换能器阵列，该虚拟换能器映射要成像的整个介质。该虚拟阵列的元素间响应形成聚焦反射矩阵，从中可以获取传播波各种特征的空间图。在这里，我们展示了（i）一种局部聚焦准则，该准则使得能够在介质内部的任何位置（包括随机散斑）评估图像质量和波速，（ii）高度解析的多重散射发生率的空间映射，这构成了超声成像的新的独特对比。该方法已针对可控幻影系统和用于人体的体内成像。更一般而言，这种矩阵方法为波物理学中的定量成像开辟了一条原始而强大的途径。