基于特征谱线的干涉型光谱仪在轨光谱定标方法研究

For spaceborne interference spectrometer, central wavelength shifts and spectral resolution changes on orbit will lead to the appearance of spikes and dips in the spectra, which may effects the facticity of the measured data. This project proposed an indirect spectral calibration method for the full working band calibration of interference spectrometer. First，base on the study of detecting principle and spectrum reconstruction algorithm, a whole process simulation system is built to simulate recovering spectra from input spectra. By this system, how instrument and recovering parameter affect wavelength position and resolution is researched, and the quantitative relation between them is established. Then, a spectrum-match technique base on spectral characteristic lines is employed to scale the key interference parameters, by the accurately match between simulated and observed spectrum. And wavelength position and resolution are calibrated indirectly according to the quantitative relation. In this method, spectral deconvolution algorithm is replaced by interference data simulation and spectrum reconstruction process to simulate the observed spectrum, which is accord with the indirect detection principle of interferometer spectrometer. This is a new on-orbit spectral calibration method, which can improve the calibration accuracy and frequency.

星载干涉型光谱仪在轨运行中，波长偏移和带宽变化将导致光谱曲线出现尖锐毛刺而影响光谱的真实性。本项目提出一种间接实现干涉型光谱仪全工作波段在轨光谱定标的方法。通过对典型光谱仪探测原理和光谱复原算法的分析研究，构建从入射光谱到复原光谱的全过程仿真系统，并利用该仿真系统探索干涉参量（仪器参数和复原参量）对波长位置和分辨率的作用机理，建立两者间的定量关系模型。采用基于太阳或大气特征谱线的光谱匹配技术，通过模拟与观测表观辐亮度光谱间的精确匹配，实现关键干涉参量的标定，并依据建立的定量关系模型，间接实现波长位置和分辨率的准确定标。该定标方法使用干涉数据仿真与光谱复原过程，代替传统算法中的光谱卷积过程，解决了无光谱响应函数情况下，如何利用超高光谱降分辨率得到准确模拟观测光谱的难题。它符合干涉型光谱仪间接探测目标光谱的物理原理，是一种能提高在轨光谱定标精度和频次的新方法。

针对干涉型成像光谱仪传统在轨光谱定标方法单参数、窄波段检测，且无法在全工作波段同时对光谱波长位置和分辨率定标的问题，提出基于特征谱线的间接在轨光谱定标方法。该方法根据傅里叶光谱学原理，构建与波长位置和分辨率直接相关的干涉参量网格，将其用于光谱复原，通过优化迭代算法求解与特征谱线最匹配时干涉参量的网格值，用于全工作波段波长位置和分辨率的计算，这对可用特征谱线较少的可见短波红外高光谱成像仪在轨光谱定标具有重要意义。同时针对该方法在超高光谱分辨率光谱仪定标中，复原DN谱存在特征谱线不易识别的问题，提出了多谱线拟合的直接定标方法，通过特征谱线筛选、多普勒频移修正、谱峰位置确定处理，实现了超高光谱分辨率光谱仪高精度在轨光谱定标，为其数据反演应用提供基础保证。对HJ1A高光谱成像仪HSI、高分五号温室气体监测仪GMI和红外甚高光谱分辨率探测仪AIUS的光谱定标，很好地验证了方法的有效性。