基于傅立叶变换红外光谱仪的太阳光谱观测系统定标方法研究

The solar mid-infrared spectral observation with high resolution has lots of advantages in the accurately diagnostic of solar atmosphere model and in the accurate measurement of solar magnetic fields. Up to now, There is no the other choice except for Fourier Transform Infrared Spectrometer (FTIR) if one wants to get high resolution solar spectrum. We hope to carry out high resolution solar spectral observations with FTIR in China. The project mainly has two goals. One is to do the calibration of solar spectral observing system with high accuracy, because the non-linearity of the detector, the sidelobes and the additional phase from the FTIR will influence the intensity, asymmetry, and line center position of a spectral line. The other is to identify, isolate and correct the atmosphere spectral lines from the observational spectrum in order to get the real solar spectrum. To achieve the goal, firstly the simulated analysis based on the synthetic solar spectral profiles considering different instrumental effects will be employed to optimize the corresponding correction algorithm. Then the calibration process will be done not only in the laboratory and but also on the solar observing system to test the feasibility of the calibration algorithm developed in the above-mentioned simulated analysis. Lastly, we hope to have some test observation on the quiet or active regions of the sun. With the project, some scientific preliminary research can be conducted, which is important for the China Giant Solar Telescope and the Accurate Infrared Magnetic field Measurements of the Sun. Moreover, we can also develop some calibration methods which is very useful for the above two projects.

中红外波段的高分辨太阳光谱观测在精确诊断太阳大气模型、精确测量太阳磁场等方面蕴含着巨大的科学潜力，当前傅立叶变换红外光谱仪（FTIR）几乎是获得红外高分辨率太阳光谱的唯一选择。本项目在国内率先开展基于FTIR的高分辨太阳光谱观测。针对甚高分辨率FTIR仪器响应的非线性、旁瓣、附加相位等引起的光谱强度偏差、轮廓不对称性、线心漂移，开展高精度光谱定标方法研究；针对实测太阳光谱中混杂的地球大气谱线，在其辨别、分离和改正方面开展研究。项目首先基于模拟太阳光谱开展仿真分析，模拟各种仪器效应并发展改正算法；其次通过实验室和太阳光谱的实测数据定标，结合模拟结果，优化定标流程和算法；最后开展有限的太阳光谱科学试观测。本项目既可为中国巨型太阳望远镜(CGST)和用于太阳磁场精确测量的中红外观测系统(AIMS)开展科学预研究，也可为其红外光谱数据的定标储备方法。

中红外波段的高分辨太阳光谱观测在精确诊断太阳大气模型、精确测量太阳磁场等方面蕴含着巨大的科学潜力，傅立叶变换红外光谱仪（FTIR）几乎是获得红外高分辨率光谱的唯一选择。本项目在国内率先开展了基于FTIR的天文光谱观测。针对甚高分辨率FTIR中红外太阳光谱观测中面临的四大核心问题——光谱图到干涉图反演（含相位矫正和切趾函数选择）、高光谱分辨率检测、探测器非线性、仪器和大气背景开展了细致研究。取得的成果包括：（1）建成基于傅里叶变换光谱仪的太阳光谱观测系统一套；（2）建立了傅里叶变换光谱仪仿真分析工具、高光谱分辨率检测方法、干涉图到太阳光谱图反演程序、基于模拟退火算法的傅里叶光谱仪非线性改正程序、大气识别和改正以及大气背景测量改正流程；（3）获得太阳宁静区0.4-25μm高分辨率光谱数据集一份；（4）聚焦未来傅里叶变换光谱仪的发展趋势，在国际上率先开展了面阵傅里叶太阳光谱仪的技术探索，搭建了基于CMOS传感器的高速采集系统，并取得了宁静区二维太阳光谱。本项目为国家自然科学基金委重大科研仪器研制项目——“用于太阳磁场精确测量的中红外观测系统（AIMS）”项目储备了技术和科学基础。