扫描非均匀性对点目标探测影响

为了深入研究物方扫描机构与点目标探测性能的关系,定义了度量扫描机构运动特性的扫描非均匀性指标。根据扫描成像的物理过程,建立了线阵探测器扫描成像模型,并以目标信噪比为核心分析了TDI探测器下扫描非均匀性的影响。首先,根据物方扫描工作特点设置了与扫描机构工作方式相配合的探测器积分时序,并建立了扫描非均匀性度量参量;其次,在经典成像模型的基础上建立了符合积分时序和TDI工作原理的点目标成像模型,并结合探测器噪声模型和TDI工作原理推导了目标信噪比计算公式,通过该公式分析了不同光学系统、TDI级数及目标尺度条件下目标信噪比与扫描非均匀性的关系;最后,从保证能够目标检测性能的角度给出了在相对信噪比限制条件下扫描非均匀性上限。所建立的成像模型准确反映了扫描探测系统各部分特性,分析结果对探测系统的总体设计和指标分配具有指导意义。

Detecting performance effect on point target by scanning inhomogeneous

In order to deeply explore the relationship between detecting point target and scanning device,indicator to measure scanning feature called scanning inhomogeneous was established. According to the physical process of scanning imaging, an imaging model for scanning system with linear detector was established. Based on that model, scanning inhomogeneous affected on TDI detector for point target detecting was analyzed as the core of SNR. Firstly, integration timing order of single detector was set coordinating with the characteristics of scanning structure, and scanning inhomogeneous metric was established in the meanwhile. Then on the basis of the classical imaging model, an imaging model for point target in scanning system was established with the principle of integration order and detector systems. The SNR calculation formula was deduced combining with TDI working principle and detector noise model. With this formula, the performance of detecting point target was analyzed emphatically under conditions of optical systems, target scales and TDI levels. Finally from the view point of ensuring target detection performance, the upper limits of scanning inhomogeneous ratio in optical system was given. The established model reflects the characteristics of scanning detecting system accurately, and the analysis results are significant to guide for system design and index allocation.