远心补偿像面稳定的共心多尺度系统设计

Design of Concentric Multi-Scale System with Telecentricity Compensation for Image Plane Stability

目前的共心多尺度系统普遍存在子相机像面不稳定的问题,这一问题直接导致了在后续的图像拼接中易于出现图像拼接错位,严重影响系统成像质量。针对这一问题,提出了一种基于像方远心光路的方法,该方法提高了子相机像面的稳定性,为后续的图像拼接减轻了压力。首先对错位现象出现的原因进行了理论分析,从理论层面分析了引入像方远心光路对改善成像系统的作用,最终设计了成像性能优异的基于像方远心光路的共心多尺度成像系统,其焦距为60 mm,F数为3,远心度小于0.2 mrad,总视场为70°,各视场弥散斑半径小于所选探测器的像元尺寸,在奈奎斯特频率为108 lp/mm处各视场的调制传递函数均大于0.6。像方远心结构的共心多尺度成像系统可以从光学结构部分改善子相机像面不稳定的问题,从而提高后端图像拼接的拼接质量和拼接效率,为后续的共心多尺度系统设计提供了更多的思路和技术途径,具有重要的理论和实践意义。

At present,concentric multi-scale systems generally suffer from an unstable image plane of the sub-camera.This problem directly leads to image misalignment in subsequent image stitching,which seriously affects the imaging quality of systems.In response to this problem,this paper proposes a method based on the image-side telecentric optical path to improve the image plane stability of the sub-camera and reduce the pressure from the subsequent image stitching.The paper firstly explores the reason for misalignment and then analyzes the benefits of using the image-side telecentric optical path in the concentric multi-scale systems.Finally,it designs a concentric multi-scale imaging system based on the image-side telecentric optical path with good imaging performance.The imaging system has a focal length of 60 mm,an F number of 3,a telecentricity of less than 0.2 mrad,and the total field of view of 70°.The defocused spot radius in each field of view is smaller than the pixel size of the selected detector,and the modulation transfer function(MTF)of each field of view is greater than 0.6 at the Nyquist frequency of 108 lp/mm.The concentric multi-scale imaging system with the image-side telecentric structure can improve the image plane stability of the sub-camera from the aspect of optical structure,thereby improving the quality and efficiency of subsequent image stitching.This paper also provides more ideas and technical approaches for the future design of concentric multi-scale systems,having important theoretical and practical significance.