Optical design of dual aperture infrared zoom optical system

In this paper, the narcissus of short focal length system was analyzed. A method of dual aperture zoom system was propounded, and a dual aperture infrared optical system was designed. The focal length of this zoom system at 3.7-4.8 m was 30 mm、150 mm and 300 mm with a zoom ranger of 10:1, F-number of 4 and 100% cold efficiency. The narcissus between dual aperture and normal single aperture was analyzed and compared,and the narcissus of dual aperture can be controlled preferably. The dual aperture zoom system has good image quality, big zoom range, low narcissus of small focal lens and compact configuration, so it can be used in the high thermal imager widely.