Optical design of temperature self-adaptive dual-field infrared system

Based on the theory of athermalization, an optical system of temperature self-adaptive dual field of view was designed in this paper, appling in 3μm～5μm medium wave infrared camera system. This system achieved the design of optical passive athermalization by reasonable selection in terms of infrared optical materials and aspheric surface. Only five lenses were applied in this optical system, meanwhile, optical materials like germanium, silicon and ZnSe were all ordinary and cost-effective. The focal distance was 50mm/100mm, with total length of 125mm and pixel size of 17μm. The MTF of the two field of view were both greater than 0.5 at 30lp/mm in -45°C～+60°C, with its optical performance approximating the diffraction limit.