High-tech protection

AN optical fiber vibrant sensor developed by Fudan University could be used to safeguard the 2010 World Expo in Shanghai, said professor Jia Bo, director of the university's Optical Fiber Research Center.

The Expo area is on both banks of the Huangpu River, and officials have to extend anti-terrorism measures to the river, where traditional security devices such as infrared monitors or electric fences are useless.

Jia said that the Expo organizers had shown great interest in their invention as optical fiber sensors are very suitable to disturbances in deep water.

Because optical fibers sensors are made of glass or plastic that carries light along their length, they need no electrical power and can't become rusty in the water, unlike metals.

Fudan's sensor is sensitive enough to detect vibrations in the water or air.

A machine linked to the fibers, weighing less than 4 kilograms, analyzes the transmission of light in the fiber to picture the source of the vibration, which may be caused by a person, a bird or a gust of wind.

"We plan to fix optical fibers along both banks of the Huangpu River," said Tang Huang, a member of the research center.

"If anyone tries to swim close to the bank or climb onto the flood walls, an alarm is sent immediately to the guards," he said.

The equipment was used successfully in the National Aquatics Center during the Olympic Games. The sensors accurately monitored the underwater speakers to ensure synchronized swimmers could hear the right music.

Fudan has been engaged in optical fiber technology research since 2002.