An optical positioning system for underwater arrays

An optical positioning system was designed to measure the shape of a hydrophone array underwater. The prototype used a small sensitive black and white camera as the positional detector and high intensity light emitting diodes (LEDs) as tracking targets. The system was examined for its potential range capabilities and spatial resolution underwater. Tests were conducted specifically on the range limits of the system in both freshwater and seawater. The results suggested that the system allowed target positions to be determined at ranges up to 65 m from the camera with a lateral accuracy of 26 cm. They also indicated, however, that water-born attenuators could dramatically reduce the system´s operational range limit. Field tests in near-shore waters of Nova Scotia found ranges that were closer to 20 metres at the time of the tests with the expected lateral accuracy