The Optical Design Of Compact Dual-band Systems

Airborne reconnaissance systems has the advantage of fine timeliness, all-weather, wide coverage, high resolution and strong adaptability. It can not only obtain enemy information effectively, but also track and recognize the target, which provides a strong guarantee for victory. However, compared with foreign airborne reconnaissance systems, ours exist certain deficiencies, especially quality and volume. In the paper, based on optimization of optical structure, a compact dual-band optical system is designed. Which is characterized by long focal length, wide field, dual-band.In this paper, three solutions are given. They are cassegrain, off-axial two-mirror and off-axial three-mirror common aperture imaging system respectively. The system uses off-axial three-mirror structure after comparing image quality, processing and assembling.Using a unique dichroic beam splitter, visible light and infrared light are introduced into relative light path. Long length or wide field can be obtained by changing the working mode of off-axial three-mirror common aperture imaging system. Finally, athermalizing, cold reflection analysis and tolerance analysis are listed. The results show that the visible optical path is designed zoom system with he focal length from50mm to1200mm; the MWIR optical path is designed with focal length of50mm,150mm and600mm; high image quality can be obtained from-50°to60°; cold reflection can be neglected; tolerance is reasonable. The system is characterized as long focal length, wide field, miniaturization, dual-band. It can meet the requirements of focal length, volume and image quality.