影响光谱辐亮度标定因素的分析

在利用漫反射板标定光谱辐亮度的实验装置中，标准灯完全可以近似为点光源。通过对进入光谱仪的辐射通量的数值积分，可以对应求出仪器的实测光谱辐亮度的计算公式。计算表明，实测光谱辐亮度并不等于漫反射板表面的光谱辐亮度，而有一个随标定条件变化的微小差值。通过计算，对光谱仪与漫反射板的距离、光谱仪入射挟缝的光轴与漫反射板法线的夹角以及标准灯与漫反射板的距离等影响光谱仪标定的因素进行分析，得到了最佳的标定条件。讨论了理想标定情况、光谱仪视场趋于一点的极限情况和采用实际的双向反射分布函数已知的漫反射板标定时，实测光谱辐亮度的计算情况。

Analysis of Factors Affecting Spectral Radiance Calibration by Applying a Diffuse Plane

For experimental setup to calibrate spectral radiance by applying a diffuse plane, the measured spectral radiance can be obtained through integral of spectral radiation flux entering the spectrometer. Calculation shows that the measured spectral radiance by the spectrometer is not equal to the spectral radiance on diffuse plane surface, there is a deviation varying with actual calibration condition. The effect caused by variation of distance between spectrometer and diffuse plane, angle from the light axis of the spectrometer′s entrance slit to the diffuse plane′s normal, distance between standard lamp and diffuse plane are analysed, and optimized conditions for spectral radiance calibration are obtained. Finally, the idealized spectral radiance calibration, spectral radiance limit when the viewing area shrinks to a point, and actual spectral radiance calibration by applying a diffuse plane of known bidirectional reflectance distribution function at optimized conditions are discussed.