Fiber Optic Cables To Detect Tunnels

Researchers from the Faculty of Civil and Environmental Engineering at Technion, Israel Institute of Technology have developed an interesting technology to identify and locate the exact position of underground tunnels. This is very useful technology, especially in times of war, when underground tunnels are often used to smuggle prohibited goods and arms into warzones. In some places of the world, underground tunnels are even used to smuggle people across international borders.

Researchers from Technion have used the same kind of fiber optic cables in this technology that are commonly used for telecommunication systems across the world. This system is capable of pinpointing the position of any tunnel, no matter how narrow or wide it may be, at depths more than 60 feet below the surface of the ground. This system is so sensitive; it can locate and identify cracks and strains that are caused in the ground by the process of excavation.

The ground can be affected by a number of disturbances including water percolation and erosion. This unique system is able to create simple profiles for each variety of strain found in the ground and eliminates those that can be caused by natural causes. Using this process of elimination, it can identify the exact variety of strain caused in the ground due to excavation.

This system is based on an existing technology called BOTDR (Brillouin Optical Time Domain Reflectometry) that can measure ground distortion along 15 miles using one device. It then supplies a continuous profile of soil distortions to the device through a fiber optic cable which then performs the function of identifying those ground strain profiles that characterize the process of excavation.
The new technological wonder will be presented in Orlando, Florida, at the Defense, Security and Sensing Conference of SPIE (an international society advancing light-based research) in April 2009.