Sensor Technology for Anti-Submarine Warfare

A new underwater acoustic sensor is described based on laser remote sensing. Such a sensor has several advantages over conventional hydrophones, including insensitivity to flow noise and the capability of forming a virtual array in three dimensions. Thelaser waveform and novel signal processing algorithm make it possible to suppress noise sources that have hindered previous such attempts. These include Brownian motion, ambient turbulence, optical refractivity fluctuations in ocean water, and platformmotion. Analysis, computer simulations, and laboratory experiments are used to verify the principle of operation and predict the sensor1s performance in the ocean. Results show an acoustic sensitivity advantage of 25 dB over previous attempts. Thistechnology has wide applicability in the field of underwater acoustics. If proved practical it would be used on many undersea platforms including submarines, towed arrays, torpedoes, and unmanned underwater vehicles. This means that major segments of theUS Defense Community are potential customers. To the extent that sound is the main mechanism for remote sensing underwater, this technology would represent a major advance in that field.