高温目标辐射亮度比的方向性研究

Directionality of radiation ratio of high temperature target

为研究高温目标在短波红外发射辐射的方向性,建立多角度观测物理模型;以燃烧竹炭作为小面元高温目标,在暗室条件下使用ASD FieldSpec3光谱仪对高温目标的辐射亮度进行多角度观测和分析。仅使用一台光谱仪无法同时获取多个角度的观测数据,且以不同角度观测时,高温目标温度发生明显改变,本文采用一种自定义的降温模型计算多角度观测的参比辐射亮度,并提出一个概念-辐射亮度比(多角度辐射亮度/参比辐射亮度),用以消除高温目标降温的影响。结果表明,降温模型精度很高,辐射亮度比这一概念很好地刻画了高温目标在短波红外辐射的方向性,余弦函数、傅里叶级数均可实现对辐射亮度比随角度变化的高精度拟合。

To study the directionality of radiation emitted by high temperature targets in short wave infrared, a multi-angle observation physical model is established. The burning bamboo charcoal is used as a small-surface high temperature target, and the radiance of the high temperature targets is observed and analyzed from multi-angle by an ASD Field3 spectrometer under darkroom conditions. The observation data of multiple angles cannot be acquired simultaneously using only one spectrometer, and the temperature of the high temperature target changes significantly when observed at different angles. In this paper, a custom cooling model is used to calculate the reference radiance of multi-angle observations, and a concept -radiance ratio (multi-angle radiance / reference radiance) is proposed to eliminate the effect of high temperature target cooling. The results show that the accuracy of the cooling model is extremely high. The directionality of high-temperature targets can be well characterized by the concept of radiance ratio in short wave infrared radiation. High-precision fitting of the radiance ratio with angle can be achieved by a cosine function and a Fourier series.