光阑衍射对“猫眼”回波功率分布的影响

Influence of aperture diffraction on power distribution of echo wave in cat-eye system

"猫眼"效应在激光主动侦察等领域具有广泛的应用,猫眼回波的功率分布是一项关键技术指标。激光束通过光阑会发生受限衍射,以Collins公式为基础,推导了猫眼回波光场的分布函数,数值计算了探测面上的光场分布,研究了"猫眼"系统中透镜口径、焦距以及探测距离、激光束束腰、离焦量等对猫眼回波功率分布的影响。并基于CCD搭建实验系统对猫眼回波功率分布以及衍射图样进行观测。观测结果表明:回波光场携带明显的衍射信息;探测器偏离成像透镜焦平面时,有限探测距离内猫眼回波光斑的峰值功率随着探测距离的增大而先增大后减小,最大值出现在约100cm处。观测结果与理论数值计算吻合很好,验证了光阑衍射效应对回波功率的分布造成了明显的影响;研究结果对猫眼主动探测系统的研制具有很好的指导意义。

The power distribution of the echo wave is a key parameter for cat-eye detecting system and is usually affected by the aperture diffraction. The field distribution function of the cat-eye echo wave was derived according to the Collins formula and numerically calculated. The impacts of the caliber and focus length of imaging lens ,the detection distance, the beam waist and the defocusing amount on the power distribution of cat-eye Moreover,a charge coupled device （CCD） based experimental sy power distribution of cat-eye echo wave and the diffraction patte dicate that, the optic field of the echo wave carries obvious dif detector locates away from the focus plane of the imaging lens echo wave were investigated. tance, the peak power of the cat-eye echo firstly increases and then decreases as the detecting distance increases, the maximum power emerges at about 100 cm. The observing result agrees well with the theoretical analysis,validating that the aperture diffraction can have a significant influence on the power distribution of echo wave. The investigation can provide an instruction for building a cat-eye based detecting system.