无人机等弱小目标具有飞行高度低、反射截面小、热信息弱等特点，尤其在低照度背景下，单一成像方式难以实现对弱小目标的探测和识别。实验对比了可见光成像、微光夜视成像、长波红外成像、激光主动照明成像等对弱小目标的成像效果，目的是研究适用于不同照度背景下弱小目标的探测识别方法。外场实验中，被测目标为小型四旋翼无人机，尺寸为290 mm×290 mm×196 mm，实验环境照度在10^?2~10^?4 lx之间，作用距离范围0.5~2 km。成像实验结果表明：普通可见光系统无法在环境照度低于10^?2 lx时成像；环境照度为10^?3 lx时，微光夜视和长波红外热系统的识别距离仅为0.5 km；近红外激光（中心波长808 nm）主动照明与微光夜视结合的主动成像方式可增加对弱小目标的识别距离，同等条件下主动照明成像作用距离是被动成像的3倍。

Weak small targets, such as unmanned aerial vehicles, have the characteristic of low flight height, small reflection cross-section and weak thermal information, which are difficult to detect and recognize in low-light-level background by a single imaging method. The visible light, low light night vision, long wave infrared and laser active illuminated imaging experiments were carried out, to study the suitable detection and recognition methods by comparing of weak small target images in different low-light-level background. In the field experiment, the target was a small four rotor UAV with the size of 290 mm×290 mm×196 mm, and the environmental illumination was between 10^-2 lx and 10^-4 lx. The working distance was from 0.5 km to 2 km. The experimental results show that simple visible light system cannot image under 10^-2 lx environment illumination; the recognition distance of low-light night vision and long-wave infrared system is only 0.5 km when the environment illumination is 10^-4 lx; the active imaging method combining near infrared (central wavelength 808 nm) laser illumination and low-light night vision can increase the recognition distance of weak small targets; under the same condition, the active illuminated imaging working distance is 3 times of the dynamic imaging.