Design of cold MWIR/LWIR infrared dualband/dualfield panoramic optical system

In order to identify that two bands information of the medium wavelength infrared radiation (MWIR) and the long wavelength infrared radiation(LWIR), realize the fast switch of two different fields of view(FOV), and further enhance the efficiency and range of existing systems to detect, a fourchannel cooled infrared dualband dualfield panoramic imaging optical system was designed by using the method of spatial multicamera image mosaic panoramic imaging. The panoramic system is consisted of three infrared lenses with mutual intersection angle of 120 in circularviewing direction and one infrared lens in top view direction, each optical system of imaging channel is designed to be the double imaging configuration.The Fnumber is 2, the working band is MWIR 3.5 m～4.8 m and LWIR 7.8 m～9.8 m, the full field of view(FOV) is 122 , the ratio of long focal length to short focal length is 5, and it can complete 122 /44.49 dualfield transformation through the moving of the zoom configuration in axial direction. By adopting the refractive /diffractive hybrid optical elements and introducing aspheric design technique, the system was made temperature compensation by the means of optical passive athermalization. The result indicates that the system has almost 100% efficiency of the cold stop and a good ability of narcissus restraining. At the Nyquist frequency of 18 lp/mm, the modulation transfer function (MTF) values of LWIR optical system are all greater than 0.3 , and that of MWIR are all greater than 0.5.The image plane is stable and the image quality is excellent when the system works on -40 ℃ ~ + 60 ℃.