Bomb-Detection Technology Useful for Countermine Ops.

• Author: Erwin, Sandra I.

An explosive-detection technology developed for aviation safety could improve the ability of U.S. forces to locate and clear landmines, said Army and Navy scientists.

Unlike other areas of warfare, military countermine operations have not benefited significantly from advances in technology during the past several decades. Battlefield mine detection today essentially relies on metal-detector beachcombing devices that have been used since World War II.

To be sure, the U.S. Army is developing more advanced minesweeper vehicles equipped with ground-penetrating radar, infrared sensors, as well as the old metal detectors. But these systems suffer from high rates of false alarms and, because a lot of the work involves manually digging out mines or mine-like objects, the process is painfully slow.

The big breakthrough that has eluded scientists in the United States and elsewhere could come soon, as a result of research and development work funded by the Army, the Navy and the Defense Advanced Research Projects Agency (DARPA).

The technology that experts say could revolutionize mine detection is called quadrupole resonance, or QR It is a variation of the commonly used magnetic resonance imaging (MRI) technology, which physicians rely on to diagnose patients. It is also the same technology that scans baggage at airports and can detect explosives.

The MRI machines found at hospitals are large magnets, which affect the magnetic properties of the nuclei of the water in the human body. Those magnetic properties enable the machine to generate an image.

QR, however, does not use a magnet. The technology operates under the principle that a magnetic resonance signal can be detected from explosives without applying a large external magnetic field.

This is how QR works:

* A transmitter emits pulses of low-intensity radio waves.

* Nuclei within the explosive are momentarily aligned with the radio waves.

* After each pulse, the nuclei emit a characteristic radio signal, like an echo.

* The signal is picked up, amplified and analyzed.

* A computer issues a warning if it identifies a signal that is emitted only by explosives.

Pioneering developments in QR took place at the Naval Research Laboratory (NRL) in the early 1980s, explained Allen Garroway, a research physicist at the lab. "I was familiar with work that had been done in the United States in the 1970s on the use of QR for explosive detection," he said in a recent interview. That work was discontinued after the end of the Vietnam War.

But Federal Aviation Administration (FAA) officials came to NRL in 1983, looking for advice on how to use the QR technology for detecting...