激光侦听系统的自动聚焦优化实现

Optimization automatic focusing implementation of laser interception system

针对激光侦听系统在远距离工作时由于激光的固有发散角导致目标处光斑过大,造成接收信号质量较差的问题,采用对发射激光进行自动聚焦以优化系统侦听性能的方法。基于Altera公司的Cyclone IV系列FPGA开发平台,结合测距模块与电动变焦镜头,实现了激光自动聚焦功能。利用数字图像相关法对接收散斑图像序列进行计算,从而获取目标语音信号,并将其与原始语音信号进行频谱相似度计算以衡量侦听性能。实验结果表明,通过自动聚焦使激光的光束发散角减小为原来的0.23%~0.28%(0~40 m),相较对照系统而言,有效侦听距离增加了200%~400%,侦听性能得到了显著提升。

When the laser interception system works at a long distance,the method of automatically focusing the emitted laser to optimize the interception performance of the system is adopted to solve the problem of poor received signal quality caused by excessive light spot at the target due to the inherent divergence angle of laser.The function of automatic laser focusing is realized based on Altera’s Cyclone IV series FPGA development platform,combined with ranging module and electric zoom lens.The target speech signal is obtained by calculating the received speckle image sequence with the method of Digital Image Correlation,and the spectral similarity between it and the original speech signal is calculated to measure the interception performance.The experimental results show that the divergence angle of the laser beam is reduced to 0.23%~0.28%(0~40 m)of the original by automatic focusing,and the effective interception distance is increased by 200%~400%compared with the contrast system,so the interception performance is significantly improved.