一款宽光谱鱼眼镜头的设计

Optical Design of a Wide Spectral Fish-eye Lens

讨论了一款用于监控侦查的鱼眼镜头设计.首先根据使用要求,选择了可以由图像直接提取出目标方位信息的等距离投影方式;又由系统对目标分辨率的要求,选择了焦距相对较长的全帧成像形式.通过合理布局系统结构及材料选择,使各种像差得到较好的校正,并通过加大光阑慧差改善系统照度均匀性.最终设计出工作波段486～900nm,视场180°,F/2.8的宽光谱鱼眼镜头,设计结果系统全视场在乃奎斯特频率63lp/mm处的调制传递函数大于0.3,边缘视场照度大于中心视场照度的50%,f-θ畸变小于3%,各项指标满足系统要求.

The optical design of fish-eye lens used for monitoring is discussed.First,based on the system requirment,the equidistance mapping mode in which the directional information of object can be deduced directly from image is selected,then the full frames imaging form is chose for it′s relative longer focal length,which can satisfy the resolution demands of system.Through arranging the configuration and choosing materials rationally,the abberations of system are corrected efficiently.And the drop-off of illumination at the full field of view is alleviated by increasing the pupil coma intentiaonally.Finally a wide spectral fish-eye lens is presented,whose operating wavelength range is from 486 nm to 900 nm,field of view is 180°,and F number is 2.8.The design results demonstrate that the MTF at Nyquist frequency 63 lp/mm is higher than 0.3,the illuminance at the edge field of view is higher than 50% of central field of view,and the f-theta distortion is less than 3%.All indexes satisfy the commands of system.