Sound Speed and Probe Misalignment Estimation for Diverging-Wave Imaging of Pipes

Ultrasound imaging is widely used in nondestructive testing (NDT) of various industrial structures, e.g., inspecting liquid-filled pipelines to assess their structural integrity. In this context, our work pertains to receive beamforming of diverging-wave imaging data acquired by an immersed transducer array probe positioned inside a pipe. We present a simple and effective method for estimating the speed-of-sound values and probe positioning errors, which is needed for calculating signal travel-time delays with higher accuracy, leading to better-quality multimode images produced by a delay-and-sum beamformer. Our imaging results demonstrate the importance of sound speed and probe misalignment estimation based on experimental data acquired by a 256-element probe.