Research On The Warning Technology Of Anti-laser Eavesdropping Based On AOTF Camera

Due to the indirect irradiation and the scattering of the glass,the existing intercepted laser warning technology cannot obtain any information of the eavesdropping source.To solve this problem,an anti-laser eavesdropping warning method using AOTF(Acousto-Optic Tunable Filter,AOTF)camera as staring image was proposed in this paper.As a core element of spectral imaging system,AOTF can obtain laser wavelength information through its continuous filtering function of near-infrared waveband and reduce the background noise.Through the acousto-optical diffraction imaging,the high-resolution staring imaging of the surrounding environment can be captured,and the feature of the laser spot can be obtained.On the basis of the basic principle of AOTF,this paper analyzed the configuration parameters and the overall schematic diagram of the constructed AOTF camera experimental platform system.In order to extract the characteristics of the scattered light spot more accurately,several key techniques are studied emphatically,such as the eavesdropping light source positioning model,the spot fitting algorithm of the scattering light,the feature information extraction algorithm and the image distortion model.According to the imaging characteristics of the warning system,firstly,we proposed an image preprocessing algorithm and a least-squares image fitting algorithm to fit the light spot.Then,on the basis of extracting the edge contours,we used the image feature information extraction algorithm to extract the scattered light spots.Finally,we derived the geometric model of the incoming azimuth of the laser source.The experimental results show that the algorithm and the constructed geometrical model can trace the location information of the incoming laser source effectively.At the same time,due to the AOTF camera's own causes,distortion will occur during imaging,which will affect the accuracy of image feature extraction.To solving this problem,this paper describes the distortion mechanism and characteristics of the AOTF camera,and proposed a distortion correction method.The experiment results show that the maximum distortion pixel displacement of the images captured by the AOTF camera with the distortion correction are 1.4 pixels,while the maximum distortion pixel displacement of raw images are 9 pixels,which means the distortion caused by the AOTF camera system has been well corrected.Finally,the experimental platform of the anti-laser eavesdropping warning system based on AOTF camera was built,the He-Ne laser is used as the laser source and the trace algorithm was written.The experimental results show that the system can obtain the position information of the eavesdropping laser light source,and the positioning accuracy of the azimuth and pitch angle is less than or equal to 4°,achieving the desired target.