Cat's eyes save lives

A nautical version of 'cat’s eyes' developed by defence scientists to mark and find underwater locations could also be used to locate oil fields or transatlantic cables, and help to avoid dolphins and whales being caught up in fishing nets.

Scientists from the Defence Science and Technology Laboratory (Dstl) have successfully shown in sea trials that the new underwater cat’s eye can reflect back a tuned signal, revealing its location, to existing sonar systems (for example, those mounted on maritime vessels).

Whales and dolphins also use sonar to navigate, so if the cat’s eye was attached to fishing net, they would be able to pick up the signal and avoid the area.

To date, battery-powered sonar location devices have been used by oil and cable companies that continually pulse a signal back to a sonar system. The new cat’s eye, however, is a passive system, meaning that it only sends a signal when sonar tries to identify it.

Another downside to using battery powered devices is that they need periodical replacement before the battery runs out. This results in significant maintenance costs, and if the battery power has died, then the devices themselves could be lost forever. The new cat’s eye does not use battery power.

Historically, passive devices have relied on toxic chlorofluorocarbons (CFCs) housed in metal disks to bounce the sound back. However, the new environmentally friendly cat’s eye system has no requirement for CFCs as its physical properties alone are powerful enough to send a signal back to the sonar.

'This is another example of Dstl technology being directed outside its original military application and making a difference to industry,' said David Harris, head of technology transfer.

Subsea Asset Location Technologies has been setup specifically to commercialise the development of the technology.