Optical Design Of Three-line Array Airborne Mapping Camera

Three-line array airborne mapping camera is a classical digital aerial photogrammetric mapping system. It can quickly acquire digitized geographic information with small volume, light weight, wide coverage, high efficiency and large B/H. Three-line array airborne mapping camera become an upgraded version of digital aerial camera in aerial photogrammetry, and so many countries paid much attention on the study of this new kind of airborne mapping camera.Because of some reasons, the research on three-line array airborne mapping camera in our country is still underdevelopment.There is a large backward in the area of aerial photographic technique when compared to other countries.Nowadays, several three-line array cameras which have been developed by foreign countries are already put into applications, such as topographic mapping, stereo mapping, and so on. However, these digital airborne mapping cameras have some shortcomings, such as small field of view, low resolution, large volume, and they are gradually hard to meet national economic construction for the requirement of large scale topographic map.How to solve the relationship between field of view and high resolution in optical system design, which has become a big obstacle in the research on three-line array airborne mapping camera with large field of view and high resolution simultaneously.The traditional high resolution camera can only take compromise between field of view and resolution, and it is also a big challenge for optical design with large field of view and high resolution simultaneously.The paper pays much attention on optical design of three-line array airborne mapping camera with large field of view and high resolution. Several optical questions are mainly researched, such as structure of three-line array camera, optical system design with large field of view and high resolution, optical splitting system for RGB multispectral imaging, and question on how to solve relationship between field of view and high resolution. The main achievements are as follows:Firstly, on the analysis of technical specification of three-line array airborne mapping camera with large field of view, three different technical routes are put forward in the study of three-line array camera. Respectively, these are non-telemetric optical system, telemetric optical system and monocentric multiscale imagers.Secondly, paper designed non-telemetric optical system, telemetric optical system separately, and make research on optical splitting system for RGB multispectral imaging and detector mosaic in each traditional technology routes, then finally results of three-line array airborne mapping camera are given.Thirdly, this paper pays deeply much attention on splitting system for RGB multispectral imaging, and proposes a novel optical method, which can solve difficult problem of RGB imaging on a close linear focal plane array detector. According to this method, optical splitting system can split rays on three linear array detectors, whose transverse dimension is only four pixels between each other.Fourthly, a new imaging techniques based on monocentric multiscale imagers is introduced to the optical design of three-line array airborne mapping camera. This new techniques can successfully resolve the contradiction between large field of view and high resolution.Paper pay deeply attention on the concentric objective, derive paraxial imaging formula, analysis of the concentric aberration characteristics and imaging properties of monocentric multiscale imagers, and then give parameter estimates on system design, aperture arrangement of relay optical system on a sphere. Finally, optical system of three-line array airborne mapping camera with large field of view and high resolution is designed, which based on this novel method of monocentric multiscale imaging.As the promotion of linear array monocentric multiscale imaging system, paper carried out research on plane array detector imaging system with large field of view(FOV) and high resolution. A monocentric multiscale imaging system with focal length 60 mm and FOV is 100×60 degree is designed. This monocentric multiscale imaging system is Gigapixel wide field of view visible imager.Finally, three kinds of optical system of three-line array airborne mapping camera on different technical routes are compared, and advantages between traditional optical system and monocentric multiscale imaging system are analysed.As a result, non-telemetric optical system is choosen as the finally optical system of three-line array airborne mapping camera.The results also show that monocentric multiscale imaging system can avoid a series of technical challenges, such as optical design, detectors mosaic, and so on. It is an effective way to achieve high resolution imaging with large field of view.It will be the best choose in the application of imaging with large field of view,which can not achieved in traditional way.