Optical design of long focal length and wide field on an aerial CCD camera

Abstract

Reconnaissance range and image resolution are increasingly paid more attention to with the development of airborne reconnaissance, the optical system should be in characteristics of long focal length and wide field. At the same flight altitude, the wider field can enlarge ground covering width and increase the reconnaissance range Longer focal length can improve ground sample distance (GSD). Merits and advantages of reflecting system, catadioptric system and refractive system were represented, with the help of code V software, a refractive system was designed to meet the requirements, Optical material with special dispersion was adopted to remove second order spectrum. It has a focal length of 903mm, with the field angle of 4.5°×4.5°, the size of CCD pixels is 10um×10um, spectral scope is from 0.43um to 0.74um, modulation transfer function(MTF) is all above 0.5 in whole field when spatial frequency is at 50lp/mm, distortion is less than 1%, image quality reaches the diffraction limit. The system with long focal length and wide field can satisfy the demand of the wide ground overlay area and high resolution, and can apply in high altitude photograph.