宽覆盖高分辨率机载相机光学系统设计

针对机载相机广域高效航拍作业需求,采用新型级联光学成像结构,设计了一种宽覆盖高分辨率机载相机光学系统。该系统由对称前置同心物镜和中继转像透镜阵列组成,对称前置同心物镜获取剩余像差均匀的宽视场曲面像,中继转像透镜阵列对该曲面像进行视场细分、剩余像差校正及中继成像。所设计的机载相机光学系统焦距为60 mm、F数为3.4、视场角可达132°。基于一阶理论和像差特性,在不同飞行高度对地观测时,研究了机载相机光学系统的成像质量与宽视场曲面像的关系,获得系统在不同飞行高度实现清晰成像的方法。通过像质评价,结果表明,优化设计的系统在低空、中空及高空进行对地观测时,像面光线追迹点列图方均根半径均优于1.6μm,在奈奎斯特频率为230 lp/mm处,调制传递函数均达0.4,系统成像性能优异且像质均匀。新型级联光学成像系统适用于不同飞行高度的机载相机。

Optical System Design of Wide-coverage and High-resolution Airborne Camera

In this study,a wide-coverage and high-resolution airborne camera optical system is designed for wide-area and efficient aerial work demand of airborne camera.The optical system adopts a novel cascade structure of optical imaging consisting of a fore monocentric symmetric objective and a relay lens array.The fore monocentric symmetric objective obtains a wide field-of-view curved surface image with uniform residual aberrations.The relay lens array simultaneously performs the field-of-view subdivision,residual aberration correction,and relay imaging for the curved surface image.The optical system in the designed airborne camera has 60 mm focal length,3.4 F number,and 132°field-of-view angle.The relationship between the imaging performance of the airborne camera optical system and the wide-field curved image at different flight altitudes is studied herein based on the first-order theory and aberration characteristics.A method for achieving clear imaging at different flight altitudes is also obtained.The image performance evaluation results show a good image quality when the optimized design system performed ground observation at low,hollow,and high altitudes.The modulation transfer function reaches 0.4 at the Nyquist frequency of 230 lp/mm,and the root mean square radius of the system′s ray tracing spot diagram is less than 1.6μm,verifying that the designed cascade optical imaging system is suitable for airborne cameras with different flight altitudes.