Seeing underwater with background noise

Recent experiments have shown that images of underwater objects can be created using ambient noise as a source of illumination. A new acoustic lens, known as ADONIS, has been designed, consisting of a spherical reflector three metres in diameter with an array of 128 hydrophones at the focus of the dish. A prototype system has already been tested with the help of killer whales. The authors believe acoustic-daylight imaging should prove useful for a variety of purposes, from harbour security to underwater mine detection.; Today, it is gradually being recognized that with a technique called acoustic-daylight imaging, sounds in the sea can 'illuminate' submerged objects, thereby creating moving color pictures without sonar. Recent experiments have shown that images of underwater object can indeed be created by using ambient noise as a source of illumination. The results are sufficiently encouraging that it is believed that acoustic-daylight imaging should prove useful for a variety of purposes, from harbor security to underwater mine detection.