红外高光谱干涉仪辐射定标误差敏感性因子的仿真分析

Simulation analysis of error sensitivity factors in radiometric calibration of infrared hyperspectral interferometer

鉴于对高精度高时空分辨率大气探测资料日益增长的科研和业务需求,我国正大力发展星载红外高光谱探测系统。星载红外高光谱干涉仪光机结构复杂,仪器状态会显著影响其定标精度。本文通过理论分析和仿真实验,分别讨论了内黑体发射率、低温黑体发射率、内黑体与环境温度差、非线性系数以及直流电压演算等误差敏感性因子影响辐射定标精度的特征。分析表明定标辐射偏差的绝对值与内黑体/低温黑体发射率呈线性关系,且与内黑体与环境温度差、非线性系数、直流电压呈正相关;提高内黑体发射率和低温黑体发射率到0.985以上、控制内黑体与环境温度差在0.6 K左右、控制干涉仪的非线性效应系数低于0.04,这些方案均是实现0.1 K辐射定标精度的必要条件;辐射定标参数对定标辐射的影响特征结合地面真空实验的定标参数估计,可以迭代得到已测得和未知的定标参数的最优估计,从而提高定标精度。本文的研究结果对于红外高光谱干涉仪的参数设计以及辐射定标误差来源的识别和订正有着十分重要的意义。

Owing to the increasing demand of atmospheric sounding data with high precision and high temporal/spatial resolution,onboard infrared hyperspectral sounding systems,such as interferometer,are being developed extensively.Because of the inherent complicated optical structure of interferometer,the calibration precision is highly affected by the status of the instrument.The sensitivity characteristics of calibration precision were analyzed in this study,with regard to the status of the instrument,such as inner calibration blackbody(ICB)emissivity,low temperature external calibration blackbody(ECB)emissivity,temperature difference between the inner blackbody and environment,nonlinear coefficient and darkcurrent(DC)voltage.The results show that The absolute value of calibration radiation deviation is linearly related to the emissivity of ICB/ECB,and has a positive correlation with the temperature difference between the ICB and environment,nonlinear coefficient,and DC voltage.To achieve the 0.1 K radiometric calibration accuracy,it is imperative to increase the emissivity of ICB/ECB to greater than 0.985.This controls the temperature difference between the ICB and environment,setting it at approximately 0.6 K and the nonlinear effect coefficient at less than 0.04.The influence of the radiometric calibration parameters on calibration radiation combined with the estimation of calibration parameters in the ground vacuum experiment enables initeratively obtaining the optimal estimation of the measured and unknown calibration parameters,thereby enhancing calibration accuracy.The findings of this study are highly significant in the design of the parameters of the infrared hyperspectral interferometer.They also aid in the identification and correction of the source of the radiometric calibration error.