Authorities in Singapore have adapted devices originally developed for a military purpose -- seeing enemies in the dark -- to help combat the spread of SARS.
The new version of the device, called an infrared fever sensing system, detects body temperatures, identifying those with fever, one symptom associated with SARS, without having to contact or even make subjects stop walking. The system, which is said to be is easy to use, was developed in a week.
Now, instead of having to pass a phalanx of inquisitive nurses, passengers arriving in Singapore simply walk past a camera. Those who appear to have a fever are taken aside for a closer look by a technician.
The device has become so coveted by immigration authorities and other officials around the world who are hoping to spot infectious people that the creators of the system are planning to begin commercial production, in partnership with the Solectron Corp of Milpitas, California.
Development of the system began with a telephone call in early April from the Ministry of Health to Singapore's Defense Science and Technology Agency, asking for a more efficient way of screening incoming passengers for fever.
"The problem wasn't new to us, because we were watching the TV," said Tan Yang How, the agency's division manager for sensor systems.
Aside from being slow and intrusive, the use of nurses to screen all incoming passengers was a waste of skilled medical staff.
"Nurses are needed back in hospital," Tan said.
The agency in turn asked the Singapore Armed Forces to lend it 50 of its thermal imaging scanners, used to help weapons systems locate targets that cannot be seen otherwise.
Together with Singapore Technologies Electronics, the manufacturer of the scanners, more than 30 engineers at the agency worked to modify the devices for the new purpose. Two flat-panel displays were added, along with an adapter to allow it to be plugged into an ordinary electrical socket. Engineers then took software originally designed to interpret thermal data to find cracks in rail lines and adapted it to search for hot people.
The finished product, which rolled into the airport a week later, is housed in a stainless steel trolley rather like a hot-dog stand. In place of an umbrella, the trolley has a camera covered in a black cowl, with only the lens protruding. One display screen sits on top of the trolley, and another is on a stand facing oncoming travelers.
The camera "sees" the warmth of objects relative to the ambient temperature, and translates that information into a video image of people walking by.
The customized software is set to display anything cooler than 34 ?C as black. Normal exposed skin at around 37?C registers as lime green, brightening to yellow as it gets warmer. Anything at 37.5?C or above, like a feverish forehead, glows bright red in the image.
The system is remarkably sensitive, able to discern temperatures to within one-half a degree at a range of 15 feet. It can see bodies much farther away, though less precisely.
Of course, not every fever is a sign of SARS, and a fever is not the only reason a person might redden on the screen, according to Ace Cheong, an operator of one of the devices.
A sunburn, a few drinks of alcohol or just some brisk exercise might raise skin temperature enough to earn a trip to the special cubicle nearby for an encounter with an oral thermometer, Cheong said. He said that having eaten mutton or smoked a cigarette recently can also produce a red response.