弹光调制傅里叶变换光谱技术研究

The Study of Photo-Elastic Modulator-Based Fourier Transform Spectroscopy

为进一步提高弹光调制傅里叶变换光谱仪光谱分辨率,提出了一种折返式弹光调制干涉仪结构,该结构通过在弹光晶体前后表面镀制相互交错的的全反射膜,并让入射光线以约10°的倾斜角入射,使得被测光束在晶体内部产生多次反射,增大光在干涉仪中的传播距离并提高了调制光程差。建立了折返式弹光调制傅里叶变换光谱仪干涉-光谱反演数学模型,并在此基础上设计搭建了相应的前置收集光系统,并进行了激光光源和氙灯光源的遥测实验,实验所得干涉条纹清晰、稳定,结果表明,所设计的多次反射式弹光调制傅里叶变换光谱仪的光谱分辨率达到13cm-1,且该方案使得光线在晶体内部产生反射,降低了光能损失,保证了系统性噪比。最后的光谱反演结果表明,所设计光谱系统的技术可行,为后续的样机研制以及光谱、辐射标定等工作奠定了基础。

In order to enhance the spectrum resolution of current photo-elastic modulator-based Fourier transform spectrometer, a multi-reflected photo-elastic modulator-based interferometer structure was proposed in the present paper.Through coating re-flecting film alternatingly on the photo-elastic crystal and light oblique incidence,and allowing the incident ray to have the multi-reflection in the crystal and exit from the other side of the crystal,the authors increased the light propagation distance in the crystal and enhanced the optical path difference at last.Based on this,the function of interference-spectrum retrieval was estab-lished,the optical system matched to the multi-reflected PEM-based interferometer was designed,and finally,the experimental system of multi-reflected PEM-based Fourier transform spectroscopy for telemetry was established.The principle of verification tests by using 671 nm laser and xenon lamp shows that the interferogram was clear and stable,and the feasibility of the principle of the system was verified.The expected result shows that the spectrum resolution of the designed PEM-FTs with multi-reflec-tion achieved 13 cm^-1 ,and its luminous flux just didn＇t reduce too much,which ensured the SNR.Through spectral inversion of the interference fringes,the technical feasibility of the spectrum system developed was verified.This work established the basic condition of prototype fabrication,radiation precise calibration,spectral calibration and instrument signal-to-noise ratio test and so on.