Athermalization design of a dual field-of-view IR optical system

Infrared imaging optical system are often asked to have good imaging performance, especially while surrounding temperature varies in a large range. Because of infrared material´s sensitivity to temperature, athermalization should be taken into account in its design process in order to meet different user´s demand. In this study we undertake the design and construction of a dual field-of-view lenses optimized for use in the infrared waveband(3.5~5μm), of which the F/# is 2, and it offers a dual EFL of 200/400 mm. Analysis show the system has fine and steady imaging performance within the range of -40 ~60°C, and its MTF curves and spot diagrams show a good image quality , besides, its length and size are permitted, which is acceptable to a certain theodolite.