超轻小宽视场高分辨无人机机载相机光学系统设计

Optical Design of an Airborne Light Weight Camera with Wide Field of View and High Resolution

针对无人机光学载荷宽视场、高分辨、轻小型、实时成像等需求,基于级联光学结构设计了一种折叠式级联相机光学系统。该光学系统主要由前置折叠同心物镜和中继转像透镜阵列组成。前置折叠同心物镜获取宽视场中间像,位于前置折叠同心物镜的同心球面上。中继转像透镜阵列对同心球面上的宽视场中间像进行视场细分、剩余像差精细校正和中继成像。优化设计得到了全视场角为109.6°、瞬时视场为7.8″,筒长仅为107 mm的折叠式级联结构相机光学系统。在全视场范围内,像面上各处光线追迹点列图的均方根半径均小于1.1μm,在空间频率230 lp/mm处,各视场调制传递函数值大于0.4,系统成像质量接近衍射极限。这种折叠式级联结构无人机机载相机光学系统视场大、分辨率高、结构紧凑,可用于无人机遥感领域,在大视场范围内获得高分辨率光学像的同时,还可实现光学系统的小型化和轻量化,具有广阔的应用前景。

For the demands of light weight and small size,wide field of view(FOV),high resolution,and realtime imaging of the unmanned aerial vehicle(UAV)optical payload,we designed an optical system suitable for the UAV camera using a folding cascade optical structure.The basic components of this system are a front monocentric folding objective and a relay imager.The front monocentric folding objective captures a spherical intermediate image with a wide FOV that is located in the monocentric sphere of the front monocentric folding objective.The relay imager array completes field subdivision,fine correction of residual aberration,and a high resolution relay image on the spherical intermediate image.After optimization,we obtained a folding cascade optical camera system with a full FOV angle of 109.6°,an instantaneous FOV of 7.8",and a tube length of only 107 mm.In the full FOV,the root mean square radii of ray tracing points on the image plane are all less than 1.1μm.At the spatial frequency of 230 lp/mm,the values of the modulation transfer function are greater than 0.4,and the image quality of the system is close to the diffraction limit.The folding cascade structure UAV airborne camera optical system has a wide FOV,high resolution and compact structure,and can be used in the field of UAV remote sensing.While obtaining a high resolution optical image in a wide FOV,it can also realize the miniaturization and weight reduction of the optical system,which has broad application prospects.