Combination of optical passive and mechanical-electrical athermalisation

A combination of passive optical athermalisation and mechanical-electrical athermalisation is proposed to overcome thermal effect, which may otherwise cause the drift of image plane. Optical athermalisation is used to obtain feasible athermalised lens group, which control the error in a small range. Then mechanical-electrical athermalisation is used to eliminate the remaining error. An infrared system operating at wavelength (7.5～10.5)m with two field of view was designed, and it functions properly at -40℃ to 60℃.