Passive Array Correlation-Based Imaging in a Random Waveguide

TL;DR

This paper demonstrates that in a weakly random waveguide, correlating recorded signals and migrating their cross correlations enables high-resolution, stable reflector imaging even with small arrays and broadband sources.

Contribution

It introduces a novel correlation-based imaging method for waveguides where traditional migration fails due to partial coherence and noise.

Findings

High-resolution localization within a wavelength scale.

Broadband sources ensure statistical stability.

Effective imaging with small aperture arrays.

Abstract

We consider reflector imaging in a weakly random waveguide. We address the situation in which the source is farther from the reflector to be imaged than the energy equipartition distance, but the receiver array is closer to the reflector to be imaged than the energy equipartition distance. As a consequence, the reflector is illuminated by a partially coherent field and the signals recorded by the receiver array are noisy. This paper shows that migration of the recorded signals cannot give a good image, but an appropriate migration of the cross correlations of the recorded signals can give a very good image. The resolution and stability analysis of this original functional shows that the reflector can be localized with an accuracy of the order of the wavelength even when the receiver array has small aperture, and that broadband sources are necessary to ensure statistical stability, whatever the aperture of the array.