Optical Design Of Athermalized Vehicle-based Infrared System

The athermal method of refractive element in infrared optical system is discussed, and specific refractive infrared optical system is designed, the result is shown that the imaging quality is satisfactory, the athermal principle of diffractive element in optical system is discussed, and a refractive-diffractive vehicular infrared lens is designed and fabricated base on the unique athermal and achromatic characteristics of the diffractive elements. The system, made from only one kind of infrared material, is with self-focusing at wide temperature range. The diffractive surface is with large feature size, which is beneficial to manufacture. The working waveband of the system is from8to12μm, the focal length is19mm, the F/#is1.1and the field of view is36°×27°. The lens, which has features of small size, light weight and compact structure, is suitable for the auto-auxiliary driving system. It is shown by actual testing that the image plane is stable in a range from—40℃to80℃without manual focusing, and the imaging quality is satisfactory.