星载紫外遥感辐射计积分球定标新方法的研究

Research on the New Technology of Calibrations of Spectroradiometer for Ultraviolet Space Borne Remote Sensing Based on Integrating Sphere

在紫外波段,使用常规手段实现高精度的辐射定标是比较困难的,这主要是由于标准灯的定标不确定度约4%和漫反射板双向反射分布函数(BRDF)的测量不确定度4%—6%所致。为了提高定标精度,本文应用积分球辐亮度定标方法[1],获得了接近理想的大面积辐亮度光源(约2%),标定了在研的星载紫外遥感光谱辐射计的亮度响应度。文中将标准灯考虑为均匀亮度的点光源,对辐射计的投影视场进行了照明因子修正。同时进行了常规的灯-板定标方法与积分球定标新方法的比较,得到了采用两种方法标定的辐射计亮度响应度有较好的一致性(3%)的结论。初步的定标数据分析比对显示,漫反射板BRDF的测量不确定度和仪器投影视场内辐亮度的计算不确定度是比对中不一致主要的来源。

In the ultraviolet wavelength range, the high precision radiometric calibration of spectroradiometer is quite difficult. It is mainly caused by the relatively larger uncertainty（4% ） in the irradiance calibration of FEL standard lamp and uncertainty（4%--6% ） in the measurements of the diffuser bidirectional reflectance distribution function（BRDF）. In this article, the calibration technique of sphere integrator is used to improve the precision of calibration, the large area uniform（ ～ 2% ） source of radiance close to the ideal one is achieved to acquire the radiance responsivities of the spectroradiometer under development for ultraviolet remote sensing from space. The FEL standard lamp is assumed to be a uniform point source to get a correction for the illuminating factor. In the mean time, a comparison between the conventional FEL ＋ diffuser method and the new sphere integrator method is performed. A conclusion is drawn that the radiance responsivities using these two techniques are consistent within 3%. A preliminary analysis of calibration data points out that the uncertainties in measurements of the diffuser BRDF and the calculation of the radiance in the FOV of spectroradiometer account for the discrepancy between the comparisons of these two techniques.