鱼眼成像型激光告警系统光斑中心亚像元定位方法  

Subpixel Location Algorithm for Laser Spot in Fish-Eye Imaging Laser Warning System

作　　者：董红军[1] 周中亮[1] 王龙[1] 

机构地区：[1]军械工程学院光学与电子工程系,河北石家庄050003

出　　处：《中国激光》2011年第9期233-239,共7页Chinese Journal of Lasers

基　　金：国防预研项目资助课题

摘　　要：光斑中心精确定位是成像型激光告警系统威胁激光准确定向的基础。分析了鱼眼成像型激光告警系统成像光斑特点,针对CMOS传感器像元非完全填充结构和大入射角区域光斑能量分布非对称造成定位误差大的问题,基于光斑高斯分布特征,提出将二维高斯分布函数积分分解为两个坐标方向一维积分的乘积,利用误差函数级数近似光斑灰度高斯积分,通过能量响应最大像元和次大像元的灰度比求解光斑中心坐标的细分算法,最后通过实验对比研究了新方法的定位性能。结果表明,本方法受像元非完全填充和镜头非对称像差的影响较小,近轴区域和入射角大于60°的轴外区域定位精度分别达到1/80和1/70 pixel,最大误差小于1/30 pixel。本方法计算相对简单、定位精度较高,且对不同位置光斑定位精度稳定,能够满足大视场激光告警装备的指标要求。The directional accuracy of threatening laser is highly dependent on the laser spot center location accuracy for the imaging laser warning system. The spot features of wide field-of-view fish-eye imaging laser warning system are analyzed. As the low fill factor of CMOS sensor and the energy distribution asymmetry of spot in big incident angle region will affect the location accuracy of spot center, an improved algorithm is proposed. Firstly, it separates the two-dimensional Gaussian function integral of pixel intensity readings into a product of two one-dimensional integrals. Then the Gaussian function integrals which are difficult to solve even by numerical means are inverted using an error function approximation approach. Finally, the spot center coordinates are derived in terms of the intensity ratios of neighboring pixels. The accuracy and stability are verified and compared with traditional algorithm by experiment. The experimental results show that this method can reduce the location error caused by incomplete fill ratio of CMOS pixel and large unsymmetrical optical aberration of fish-eye lens. The spot positioning precision in paraxial region and big incident angle region are 1/80 and 1/70 pixel, respectively. The maximum error is less than 1/30 pixel. It can satisfy the system requirements of laser warning equipment, including real time, higher precision, as well as strong stabilization for spots in different areas of CMOS sensor.

关 键 词：成像系统 光斑定位 激光告警 亚像元 填充率 误差函数 

分 类 号：V448.2[航空宇航科学与技术—飞行器设计] TN977[电子电信—信号与信息处理]