激光主动侦测系统探测能力分析

Analysis of detection capability of active laser detection systems

激光主动侦测系统可实现远距离"猫眼"目标的成像探测与识别,探测能力分析是系统设计的前提和基础。为了评估激光主动侦测系统对猫眼目标的探测能力,以激光回波功率为基础,建立了系统信噪比的数学物理模型。分析了影响探测能力的因素,数值模拟了信噪比与接收光学镜头直径、发射激光峰值功率、激光束散角以及等效反射面离焦量的定量关系。结果表明,在一定作用距离范围内,散粒噪声、背景噪声与暗电流噪声、热噪声相差至少2个数量级,系统噪声主要来源于散粒噪声及背景噪声;提高系统探测能力最为有效的方法是选用激光束散角小的光源。这一结果可用于指导激光主动侦测系统的设计。

An active laser detection system could detect and recognize cat ＇s eye targets at long distance. Detection capability analysis was the basis of system design. To assess the detection capability,a mathematical model of the system＇s signal-to-noise ratio（ SNR） was established based on laser echo power. The dependence of SNR on several factors,such as receiving optical lens diameter,laser peak power,laser divergence angle,defocusing distance was quantitively analyzed. The results show that at a certain distance,the detector noise comes mainly from shot noise and background noise which surpass dark current noise and thermal noise at least 2 magnitudes. The most effective way to improve detection capability is to use lasers with small divergence angles. The result is helpful for the design of active laser detection systems.