Reviewed by Frances BriggsJan 28 2026
A new, high-resolution 3D ultrasonic imaging technique automatically adapts to diverse concrete structures.
Study: Auto-frequency-adaptive 3D ultrasonic phased-array imaging system for highly attenuative materials. Image Credit: Nandalal Sarkar/Shutterstock.com
In a study published in AIP Publishing’s Applied Physics Letters, researchers from Tohoku University, Los Alamos National Laboratory, and Texas A&M University present their imaging system for concrete that adapts to diverse structural types.
Nondestructive testing procedures are required for concrete structures such as highways and bridges to detect internal flaws without damaging them.
Most approaches include sending sound waves into the material and capturing the waves that rebound back to produce images of what is inside and detect flaws. This method is analogous to ultrasounds, which are used to view within the human body.
However, unlike human tissue, concrete includes a variety of materials, including stone, clay, iron ore, and sand, which scatter sound waves and make clear imaging difficult to achieve.
In our approach, the ultrasonic wave is broadband, using a wide range of ultrasonic frequencies rather than operating around a single, fixed frequency. The receiver is capable of accepting an even broader range of frequencies. By automatically adapting the frequency to the material, our system improves the contrast between defects and background material in concrete.
Yoshikazu Ohara, Study Author, Department of Materials Processing, Tohoku University
High-quality imaging of concrete is difficult because waves lose strength as they pass through it owing to absorption or dispersion. It is difficult to predict which sound wave frequencies will survive the journey through the material.
To account for this uncertainty, the scientists employed two devices: One to create a wide range of frequencies to transmit into the material, and a vibrometer to collect the resulting waves. The technology can handle a wide range of frequencies, so even if ultrasonic waves are scattered by concrete materials, those that do pass through are recognized, regardless of their frequency.
No manual tuning is needed. As the concrete filters out certain frequencies, the laser Doppler vibrometer simply captures whatever frequencies remain. Unlike conventional systems, we don’t have to swap transducers or adjust the frequency beforehand. The system adapts automatically.
Yoshikazu Ohara, Study Author, Department of Materials Processing, Tohoku University
Waves departing the concrete are analyzed using imaging techniques established by the researchers in previous work and tailored particularly for broadband ultrasonic data. The end result is a high-resolution 3D image of the defect and its location within the concrete.
For a repair planner or field technician, this provides concrete information: how deep the defect is from the surface, how large it is, and how it extends in three dimensions. This makes it possible to plan repairs more efficiently. The method gives a clear 3D map of internal damage that can be directly used for maintenance and repair decisions.
Yoshikazu Ohara, Study Author, Department of Materials Processing, Tohoku University
Journal Reference
Fujikawa, Y., et al. (2026) Auto-frequency-adaptive 3D ultrasonic phased-array imaging system for highly attenuative materials. Applied Physics Letters. DOI: 10.1063/5.0291949. https://pubs.aip.org/aip/apl/article-abstract/128/4/044101/3378085/Auto-frequency-adaptive-3D-ultrasonic-phased-array