The scattered light distribution of surfaces in the long-wave infrared ($\lambda \sim {8{-}12}\;\unicode{x00B5}{\rm m}$) is measured using a small set of thermal camera images. This method can extract scatter patterns considerably faster than standard laboratory bidirectional reflectance distribution function measurements and is appropriate for passive homogeneous surfaces. Specifically, six images are used in this study, each taken with respect to a thermal light source at an angle ranging from 10° to 60° to the normal of the surface. This data is deconvolved with the shape of the light source to estimate the scattering pattern. Both highly specular (black Masonite) and diffuse (painted drywall) surfaces are tested. Errors between the estimated scattering distribution and a directly measured one using a goniometer stage and quantum-cascade laser (QCL) are less than or equal to 3% except for extremely specular surfaces where viable QCL measurements cannot be made due to the increased relative contribution of speckle noise.

中文翻译：

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基于摄影的实时长波红外散射估计技术

长波红外表面散射光分布 ( $\lambda \sim {8{-}12}\;\unicode{x00B5}{\rm m}$) 是使用一小组热像仪图像测量的。这种方法可以比标准实验室双向反射分布函数测量更快地提取散射图案，并且适用于被动均匀表面。具体来说，本研究中使用了六幅图像，每幅图像都是相对于热光源以与表面法线成 10° 到 60° 的角度拍摄的。该数据与光源的形状去卷积以估计散射模式。高镜面（黑色 Masonite）和漫反射（涂漆石膏板）表面都经过测试。