Laser vibration sensing technology can detect landmines faster than traditional techniques

There are enough landmines buried underground around the world near the equator to circle the Earth twice, but identifying and removing these explosives is expensive and time-consuming.

Vyacheslav Aranchuk, chief scientist at the National Center for Physical Acoustics, presented his research on laser multibeam vibration sensor technology at the Optica Laser Congress and Exhibition in Osaka last week. Aranchuk’s laser vibration sensing technology can detect mines in the ground much faster than previous technologies.

“There are tens of millions of landmines buried all over the world, and as conflicts continue, the number of landmines increases every day,” Aranchuk said. “This technology has military applications in ongoing conflicts and humanitarian applications after conflicts have ended.”

There are more than 110 million landmines deployed around the world, and 4,710 people were killed or injured in 2022 due to mines and other explosives left behind from past wars. More than 85% of landmine casualties were civilians, and half of the civilian casualties were children.

Seventy countries around the world, including current and former combat zones, are still at risk from landmines every day.

Landmines are easy to make and cost as little as $3 each, but identification and treatment can cost up to $1,000 each to remove.

Current mine detection relies primarily on hand-held metal detectors, a technology that Aranchuk said is dangerous and time-consuming. Metal detectors and ground-penetrating radar are ineffective at detecting plastic mines.

In 2019, Aranchuk’s research team at Ole Miss developed a laser vibration sensor that uses a line of 30 laser beams to locate buried objects at a safe distance from a moving vehicle.

Researchers’ latest technology allows them to create a vibration map of the ground in less than a second. It uses a matrix array of 34×23 beams, forming a roughly rectangular shape.

“Most modern mines are made of plastic, which makes them difficult targets for traditional metal detection methods,” he said. “That’s why NCPA developed this detection method.”

Similar to the 2019 technology, Aranchuk’s Laser Multibeam Differential Interferometer Sensor (LAMBDIS) can be used from moving vehicles, further increasing the speed of detecting buried mines.

Boyang Zhang, a former postdoctoral researcher at NCPA from Nantong, China, is a co-author of the report.

“Metal detectors often cause false positives by detecting metal objects, and (ground-penetrating radar) can be interfered with by certain soil conditions and materials,” Zhang said. “In contrast, laser acoustic detection uses a combination of laser and acoustic sensing, which allows us to detect mines from a greater distance with greater accuracy.

“By moving the operator away from the detection zone, we reduce false positives and increase safety.”

To find buried objects, explosive or otherwise, researchers vibrate the ground and shine a two-dimensional array of laser beams on it.

The vibrations in the ground cause small changes in the frequency of the reflected laser light, which is used to create a vibrational image of the area. Buried mines exhibit different vibrations than the surrounding soil and appear as red blobs in vibration images.

“The working principle is based on optical reasoning,” Aranczyk said. “When we send a beam to the ground, the interference of light scattered back from different points on the ground creates a signal that, when processed, reveals the magnitude of the vibrations at each point on the ground.”

Although the technology is aimed at detecting landmines, it could have many potential applications, the researchers said.

“Besides mine detection, LAMBDIS technology can also be applied for other purposes, such as the evaluation of bridges and other engineering structures, vibration testing and non-destructive testing of materials in the automotive and aerospace industries, as well as in biomedical applications.” he said.

The next stage of Aranchuk’s research aims to investigate the performance of LAMBDIS in different buried objects and in different soil conditions.