The Analysis Of Diffraction Efficiency Of Multi-layer Diffractive Optical Element In The Broad Infrared Waveband

In recent years, various diffractive optical elements have been widely used in all kinds of infrared imaging system, and this is mostly because the diffraction optical element can eliminate the apochromat, thermal difference, simplify the system structure and improve the degree of freedom of optical design, etc.. In spite of these advantages, the diffraction efficiency is still the main problem that restricts the application of diffractive optical elements in the infrared imaging system, especially in the application of the multi-window infrared imaging system. Therefore, it is necessary to study the diffractive optical element of the high efficiency in the infrared wide band.In this paper, the history of the diffraction and the future direction of the diffraction system were introduced. The diffraction efficiency of several diffractive optical elements was discussed, and the diffraction efficiency of the model was analyzed. The application range of the two models was discussed. The influence of incident angle, wavelength, and temperature on the diffractive element was analyzed, especially for the double-layer diffractive elements in the infrared band. The influence of different design wavelengths on the diffraction efficiency was obtained, and the appropriate design wavelength can be improved by 15%. According to the theory of double-layer diffractive optical element, a mid and far infrared optical system with-double layer diffractive element was designed, and the transfer function(MTF) of the wave is 0.6, and the long wave infrared is 0.2.