Fisheye Lens Design And Distortion Correction Algorithm

Panorama imaging system is a synthetic system whose field of angle(FOV)is extremely wide and contains much more information than other imaging systems.In the field of automotive electronics,living show and even film recording,it plays a more and more important role.Within many optical systems,fisheye lens is most widely used for its wide FOV and less obstruction.However,fisheye lens is a kind of super wide angle lens whose FOV is usually over 180 degrees,so it is very difficult to design.Designers should consider many problems such as light leakage,TIR and so on.Also,manufacture ability is very important issue because of the high power of front lens.Apart of that,the photo taken by fisheye lens is much different from the photo taken by the rectilinear lens.It contains more distortion and is not suitable for people to watch directly.Since the severe deformation of the image,distortion correction is another vital work for our research.In this article,the study of fisheye lens can be divided into two aspects,the design of a 250° fisheye lens for sports cameras and distortion correcting algorithm.The dissertation is mainly organized as follows:1.According to the cutting edge design requirement,the author designs a fisheye lens whose FOV is 250° and F/#is 2.8.The design's image quality is outstanding.2.After the design,the simulation work of relative illumination is done.The author proposes a novel method of calculating relative illumination,and compares the result with ZEMAX.Also,this article discusses the ghost image of the design,some serious ghost image paths are found.The author proposes some methods dealing with it.2.The distortion correction on fisheye image is based on projection model.This paper proposes two reasonable methods:one is for a local region of interest to be corrected into a distortion-free rectilinear projection image,the author extends this method to correct image over 180°.Another method called improved equal arc method is used to correct the whole fisheye image into a panorama.The result got from it can conserve more important information than traditional methods such as cylinder unwrapping method.3.The author builds an experimental equipment using the manufactured lens and verify the algorisms proposed by the author.