TECHNIQUE FOR DETECTION AND IDENTIFICATION OF UNDERWATER TARGET Russian patent published in 2000 - IPC

FIELD: underwater acoustics, detection and identification of barely audible underwater target in defended water area. SUBSTANCE: water surface of defended water area is irradiated from aircraft with modulated laser beam of wave length of 9- 11 μm. This radiation is completely absorbed by surface layers of water and irradiated position turns to be source of modulation of acoustic waves detected from surface craft. With appearance of target within area of propagation of modulated acoustic waves the latter are reflected from it. This makes it possible to fix presence of target in defended water area. Position of supposed location of target is irradiated from aircraft with the use of modulated laser beam of 0.6-1.1 μm wave range to define coordinates of target more precisely. Radiation of this wave length deeply penetrates thickness of water. Then this laser beam is moved ( scans ) till moment when it hits surface of target. In this case surface of target is heated and point of heating becomes source of modulated acoustic waves reaching sonic detector on board of surface craft. So spatial coordinates of target are found accurately. Finally laser beam with hollow core is directed on running unit of target from surface craft. With this artificial acoustic line channel is formed in water over which acoustic signal from running unit of target reaches sonic detector located in core of laser beam. Computer of surface craft determines coordinates and identifies target by signals received by signals. EFFECT: increased precision in determination of spatial coordinates of underwater target and diminished probability of error in identification of target. 2 cl, 3 dwg