Depth Detection Method Of Underwater Acoustic Signal Based On Acousto-optic Effect

Real-time and non-contact detection technology has become the focus of target detection research.The purpose of this paper is to obtain the depth location information of underwater sound source by analyzing the intensity of water surface wave diffraction spot,so as to lay a foundation for the research of underwater target location.Based on acousto-optic diffraction effect,the water surface acoustic detection technology studies the intensity and size of liquid surface wave diffraction spots of different sound sources into the water,so as to obtain relevant information of underwater sound sources and realize underwater sound source depth detection.The main contents of this study are as follows:(1)Based on the acousto-optic diffraction theory and grating equation,the microwave theory and dispersion relationship on water surface are analyzed,and the depth of underwater sound source and the diffraction intensity are explored and theoretically deduced,which provides theoretical support for the further use of acousto-optic diffraction method to detect underwater sound source.(2)Use screw linear module to build sound source depth detection experimental device.When the laser incident on the liquid surface,the incident light and the liquid surface have a certain angle,by adjusting the lifting optical detection device to change the depth of sound source into the water,diffraction phenomenon,obtain a clear and stable diffraction pattern.(3)Based on acousto-optic effects,the diffraction spot size of sound source with different water entry depth is studied.When the depth of underwater sound source increases,the size and order of diffraction spots decrease correspondingly,and the distribution of diffraction spots is asymmetrical.Through the research of spot recognition algorithm,the appropriate threshold value is selected to process the spot image with different water entry depth,and the spot size is determined.At different sound source depths,the size of diffraction spot decreases significantly with the increase of sound source depth,and the spot spacing is asymmetrically distributed.The experimental data are basically consistent with the theoretical analysis.(4)Based on acousto-optic effects,the intensity of diffracted spot with different immersion depth of sound source is studied.When the immersion depth of the sound source changes,the relative intensity of the light spot changes obviously.By changing the depth of underwater sound source,the diffracted light spot with different intensity can be obtained.The light spot intensity caused by the sound source with different water depth was analyzed,and the analytical relationship between the light spot intensity and the sound source depth was obtained.Based on this conclusion,the underwater depth of the sound source can be deduced according to the characteristics of the light spot.The position change of sound source in two directions is analyzed to get the change surface of relative light intensity in space position.