基于逆合成孔径成像激光雷达的自旋小目标成像系统

为了获得毫米级自旋小目标的清晰成像,采用逆合成孔径成像激光雷达技术设计了基于距离向数据与方位向数据相融合的图像重建系统。系统采用大带宽、窄线宽光纤激光器配合调制器实现激光脉冲的线性调频,利用光外差原理对回波信号进行采集处理。结合自旋目标的运动特性,给出了含有自旋分量的回波信号函数方程,并将该分量引入传统的R-D算法中实现了对自旋目标的ISAIL二维图像的重建。实验采用毫米级铝条构成被测小目标,通过步进电机及带倾角的转台完成运动及自旋模拟。实验结果显示,当目标固定时,可通过回波能量数据获得一维距离向图像,与被测目标的4个特征点位置一致。当目标运动时,通过数据压缩并代入自旋参量,最后通过R-D算法可以获得可识别的ISAIL二维图像,验证了系统符合自旋小目标成像的设计要求。

Research on Imaging System for Small Spin Target Based on Inverse Synthetic Aperture Imaging Lidar

In order to obtain clear millimeter imaging of small spin target,using inverse synthetic aperture imaging laser radar technology,image reconstruction system is designed based on the integration of distance data and direction data. High bandwidth,narrow line-width fiber lasers and modulators are used in the system,to achieve linear frequency modulation for laser pulses. According to optical heterodyne principle echo signals is collected and processed. Combined with target motion characteristics of the spin,functional equation is given containing spin component of echo signal. The component is introduced into a conventional R -D algorithm,and dimensional ISAIL image reconstruction for spin target is realized. In the experiment,millimeter aluminum is measured as small target. Target is driven by a stepping motor on the inclined turntable,to simulate target motion and spin motion. Experimental results show that when the target fixed,one-dimensional distance image is obtained from the echo energy data,consistent with the four characteristic points measured target position. When the target movement,spin parameter is substituted and data compression was completed. Finally,identify the two-dimensional ISAIL image is obtained by R-D algorithm. The system design requirements of small spin target imaging are verified.