Optical design for low-level-light color night vision systemand its image quality evaluation

In order to use visible and long wave infrared information for image fusion and color display, three dual-band imaging optical systems and theirs imaging performance were analyzed. All-refractive optical system, catadioptric optical system and off-axis three-reflection dual spectrum optical system were designed. A beam splitter was adopted to reflect visible and transmit LW infrared. Its full field of view and relative aperture are up to 5 and F/1.7, and MTF is higher than 0.60 at 50lp/mm in the visible region, higher than 0.30 at 18lp/mm in the LWIR region. The construction features of the lens are discussed, the aberration curves and MTF curves of the system are presented.