Optical System Design Of Fisheye Lenses For Applications In TV Imaging&Guidance

Compact fisheye objective lens systems that can generate high resolution images over a wide field-of-view(FOV)in real-time have potential applications in most state-of-the-art military and civilian vision applications,especially in security and targets tracking/guidance purposes where an ultra-wide FOV monitoring system is required to avoid blind sections and saving time consumed in tracking omnidirectional threats.Conventional TV cameras have limited FOVs.which limit their applications in many cases.Although modern panoramic lenses such as fisheye provide great advantages over the conventional cameras,they have also some drawbacks such as existence of large central blind section and/or some other lower resolution sections as well as relative sophisticated design requirements.It is then necessary to develop more simplified,compact,and ultra-wide FOV objective lens models being capable of producing high-resolution images in real-time without existence of any blind/lower-resolution image sections.In this dissertation,a detailed study was conducted of design,analysis,and evaluation of fisheye objective lens systems over the visual spectral band from 0.38 ?m to 0.76 ?m with various design techniques,and new foveated light projection models were proposed which would yield less complexity designs without compromising the performance of the imaging systems.The main content and contributions consists of following four parts:The design challenges and the limiting factors for the performance of fisheye objective systems were identified and elaborated.The first order design parameters for the fisheye lens starting point using the paraxial ray tracing equations were derived.F/4 and F/3.75 fisheye were designed which consist of all-spherical surfaces and have a FOV of up to 220 degree.The performance evaluations were done by ZEMAX optical design software.Results show that the high-resolution projections with excellent brightness uniformity and color problems correction were achieved.A quasi-symmetric start point design approach was then proposed which has the advantage in reducing fisheye lens system complexity and improving the overall system performance.Compact fisheye lens design technique and modeling method were presented,and performance and tolerance analyses were carried out.The image quality of the designed F/2.8 compact fisheye was as high as that of mega pixel class electronic imagers.The light projection function plays an important role in the field of designing ultra-wide angle cameras.To relate the radial distortion level to the object FOV,new ultra-wide angle projection functions were introduced that are called foveated fisheye models.The projection peculiarities and the corresponding design results were compared with the classical equidistant fisheye projection function to illustrate the benefits of the foveated projection models on real-time tracking and ultra-wide angle imaging applications.Two of the fast high-resolution foveated fisheye lens systems with a FOV of up to 170 degree and more than 52%of the entire image area/FOV a distortion-free central region,were designed through uncomplicated distortion control using ZEMAX user-defined macro program.To perform the foveated fisheye lens calibration and distorted image correction processes,the necessary theory of projective geometry was presented and reviewed.Several models used were discussed for correcting the strong radial distortion and their advantages and drawbacks were pointed out.The proposed methods of calibrating foveated/traditional fisheye camera internal parameters were provided and discussed.Foveated fisheye correction models and imaging process of different simulated radial distorted images using developed algorithms by means of MATLAB program were investigated and performed.The foveated models' correcting results and their analyses provided successful undistorted perspective images without any correction process has been executed within more than 52%of the entire distorted image area,making them more suitable for applications of real-time security and tracking/guidance multi-targets,whatever with/without fisheye's image distortion correction.Finally,our proposed fisheye objective lens models add the design simplicity and the structure compactness,and enhance the real-time imaging capability,constituting a contribution to the growing field of research in ultra-wide FOV TV-cameras and their state-of-the-art applications.