Imaging research at UCNDE lies at the interface between physics, applied mathematics, and engineering. The focus is on the theoretical and experimental aspects of wave mechanics for sub-surface sensing to address open challenges in non-destructive evaluation and structural health monitoring. The main goal is to advance wave-based imaging methods building on recent progress in solid state electronics, micromachining and computer power.

Ultrasound Tomography

Tomography attempts to reconstruct the spatial distribution of one or more physical parameters of an object by studying the perturbation induced by the object's structure on the free propagation of either mechanical or electromagnetic waves. The wave-matter interaction can be modeled according to classical ray theory or under the more general framework of diffraction theory, which includes the former in the short wavelength limit. Thus, while a ray is, in general, sufficient to describe the propagation of high-energy photons in X-ray tomography of biological materials, diffraction, refraction and multiple scattering can become dominant when imaging the same material with ultrasound or microwave. The presence of these effects poses a number of fundamental challenges to the development of tomography technology. We have shown that ultrasound tomography can be engineered to achieve the same resolution as X-ray CT but without the risks associated with ionizing radiation.

Combining time of flight and diffraction tomography for high resolution breast imaging: Initial invivo results (L)

P Huthwaite, F Simonetti and N Duric, The Journal of the Acoustical Society of America 132 (3), 1249-1252, 2012

High-resolution imaging without iteration: A fast and robust method for breast ultrasound tomography

P Huthwaite and F Simonetti, The Journal of the Acoustical Society of America 130 (3), 1721-1734, 2011

Diffraction and coherence in breast ultrasound tomography: A study with a toroidal array

F Simonetti, L Huang, N Duric and P Littrup, Medical physics 36 (7), 2955-2965, 2009

Super Resolution Imaging

The possibility of imaging the structure of a medium with mechanical or electromagnetic waves has been limited by the tradeoff between resolution and imaging depth due to the diffraction limit. While long wavelengths can penetrate deep into a medium, diffraction effects preclude the possibility of observing subwavelength structures. On the other hand, short wavelengths, which would lead to high resolution, are rapidly attenuated with penetration depth so becoming insensitive to deep features. Our aim is to overcome the diffraction limit to obtain super resolved images by combining recent advances in array technology for ultrasonic sensing with novel inversion algorithms that better describe the interaction of waves with matter.

Multiple scattering: The key to unravel the subwavelength world from the far-field pattern of a scattered wave

F Simonetti, Physical Review E, 73 (3), 2006

Guided Wave Tomography of Pipes

Accurate thickness mapping of large engineering structures is critical to assess the integrity and residual life of mechanical components subject to erosion or corrosion damage. However, in many industrial settings, it is not possible to access the region of interest directly, e.g. because of remote location or due to the presence of physical obstacles. Guided ultrasonic waves offer a promising approach to remote wall thickness loss estimation thanks to their ability to propagate over a long distance along a structure. Our research focuses on the development of a highly sensitive guided wave tomography system based on an innovative array technology and advanced inversion schemes. This technology is now being commercialized through Cincinnati NDE, Ltd. a start-up company from UC.

Guided ultrasonic wave tomography of a pipe bend exposed to environmental conditions: A long-term monitoring experiment

F Simonetti and MY Alqaradawi, NDT & E International 105, 1-10, 2019

Guided Wave Tomography of Pipe Bends

AJ Brath, F Simonetti, PB Nagy, and G Instanes,  IEEE Trans. Ultras. Ferr. Freq. Contr. 64, 847-858, 2017