Wide temperature range athermal design of low F-Number optical systems

In wide-temperature-range applications, traditional optical systems often struggle to maintain stable imaging quality, primarily because conventional athermal design methods fail to fully account for the differences in the linear expansion coefficients and refractive index temperature coefficient of glass materials at high and low temperatures. To address this issue, this paper proposes an athermal design method for wide temperature ranges. By reconstructing the thermal aberration modeling process, the method accurately characterizes the nonlinear response of thermal aberrations to temperature variation, thereby selecting glass material combinations that minimize the overall thermal optical power within the wide temperature range. In combination with the thermal expansion properties of the housing material, it effectively suppresses system focal shift. To validate the effectiveness of the proposed method, an optical system with a focal length of 100 mm, an F-number of 2.2, and a field of view of 7° was designed. Simulation results show that within the temperature range of −30°C to 270°C, the system consistently maintains high imaging performance. The modulation transfer function (MTF) remains above 0.5 at 56 lp/mm across all fields and temperatures, the spot diameter is less than 9 μm, and more than 90% of the energy is enclosed within an 18 μm circle. The above results fully verify the effectiveness of the proposed method and provide strong support for athermal design of optical systems under wide temperature ranges. Meanwhile, the method demonstrates good engineering adaptability and shows broad application prospects in the design of imaging systems for complex environments.