中波红外微型静态傅里叶变换光谱仪的设计与分析

提出一种基于微光学元件的空间调制微型傅里叶变换红外光谱仪,通过引入红外微结构衍射光学元件、多级微反射镜和微透镜阵列,实现仪器的微型化.介绍了微型傅里叶变换红外光谱仪的结构及基本原理,分析了微型准直系统和聚焦耦合光学系统的设计理论,研究了单片折衍混合准直透镜的残存像差、衍射面的衍射效率、多级微反射镜的衍射、微透镜阵列的孔径衍射和中继系统的轴向装配误差对光谱复原的影响.最后,对中波红外微型傅里叶变换光谱仪进行了建模仿真,得到的复原光谱与理想的光谱曲线比较符合,实际的光谱复原误差为2.89%.该中波红外微型静态傅里叶变换光谱仪无可动部件,且采用了微光学元件取代了传统的红外镜头,不仅稳定性良好,而且体积小、重量轻,有利于在线监测应用.

Design and analysis of medium wave infrared miniature static Fourier transform spectrometer

This paper presents a spatial modulation Fourier transform micro-spectrometer based on micro-optical elements. The infrared microstructure diffractive optical elements, multi-step micro-mirrors and microlens array are introduced to realize the miniaturization of the instrument. In addition, the structure and basic principle of Fourier transform infrared micro-spectrometer are introduced. The design theory of micro-collimation system is analyzed based on the negative dispersion, the abberation correction and the arbitrary phase modulation characteristics of diffractive optical element. Combined with the characteristics of micro-static interference system, the micro-focusing coupled optical system is analyzed and designed. Based on the wave aberration theory and the Sellmeier dispersion formula, the influence of residual aberration on spectral recovery and the diffraction efficiency of diffraction surface in single-chip hybrid diffractive-refractive collimating lens are studied. The effects of diffraction of multi-stage micro-mirrors and the aperture diffraction of microlens array on spectral recovery are studied by using the scalar diffraction theory. Furthermore, the influence of axial assembly error of relay system on the whole system performance is studied. The results show that the diffraction efficiency of the diffraction surface, the diffraction of the multistage micro-mirror and the microlens array have no effect on the recovery spectrum when the working band of the system is 3.7-4.8 μm. Finally, in order to verify the accuracy of the system design results, an optical simulation software is used to simulate the infrared micro-Fourier transform spectrum. The accuracy of the system model is verified by the simulation that the reconstructed spectrum is in agreement with the ideal spectral curve and the actual spectral recovery error is 2.89%. The medium-wave infrared micro-static Fourier transform spectrometer has no movable parts and adopts micro-optics element to replace the traditional infrared lens. Therefore, it has the advantages of not only good stability, but also small size and light weight so that it is helpful in on-line monitoring applications and provides a new design idea about the micro-Fourier transform spectrometer.