Athermal design of LWIR hybrid refractive/diffractive optical system

Thermal properties of diffractive optical element and method of design athermal hybrid infrared optical system are introduced. Athermal LWIR hybrid infrared optical system for no cooled staring detector is designed. The system consists of three lenses, the effective focal length is 100mm，the relative aperture is 1:1,the wavelength spectrum is 8~11μm, the field view is 14° and the total optical length is just 140mm. The result shows that the modulation transformation function at 17lp/mm is greater than 0.6 between -40-60°C，which prove that the system can work correctly at a large temperature range.