基于ISAIL的空间小目标成像系统设计与仿真

为了实现对空间小目标的毫米级成像,设计了基于转台模型的逆合成孔径成像激光雷达系统,实现了距离向和方位向的数据融合并完成了模拟目标的2维图像重建.系统采用窄线宽光纤激光器、大带宽电光调制器完成了对激光脉冲的线性调频,并利用外差干涉的原理提高了回波信号的信噪比.结合空间小目标的运动特性,推演了含有旋转分量的激光雷达回波信号方程.在R-D算法中代入旋转分量完成图像重建的校正,实现了对模拟空间小目标的2维图像重建.实验用毫米级铝条模拟空间小目标,用步进电机使转台匀速旋转,模拟目标旋转过程.实验结果显示:当目标固定时通过回波能量即可获得1维距离向图像,峰值位置与真实目标的特征位置一致; 当目标运动时通过数据压缩、R-D算法及旋转分量的校正可获得模拟小目标ISAIL的2维重建图像,验证了系统可实现对毫米级模拟小目标的图像重建.

Imaging System Design and Simulation for Space Small Target Based on ISAIL

In order to achieve the goal of a small space millimeter imaging,inverse synthetic aperture imaging laser radar(ISAIL)system was designed based on turntable models.Data fusion of distance and azimuth had been realized,and two-dimensional reconstruction image for simulated targets was done.The narrow linewidth fiber lasers and high-bandwidth optical modulator were used in the system,and using heterodyne interferometry principle to improve the signal to noise ratio of the echo signal.Combined with the motion characteristics of the space small target,laser radar echo signal equation containing the rotating component was derived.In the R-D algorithm,the correction of image reconstruction was completed contain rotational components,the two-dimensional image reconstruction were realized to simulated space small targets.Experimental results show that it can get a one-dimensional distance of the target fixed by the consistent position to echo energy feature image,the peak position of the real target.When target moves,ISAIL two-dimensional reconstruction image can be got by data compression,R-D algorithm and rotational components calibration for simulation small target.It verifies the system can achieve image reconstruction millimeter analog small targets.