如果材料被辐照，入射光辐射的一部分被反射，另一部分被吸收，第三部分被发射。材料的这种作用可以通过材料的物理、辐射、发光或光谱特性来描述。荧光材料可以用同样的方式描述，但其行为与作为荧光重新发射的辐射部分的源相同。反射、透射、荧光和总辐射或亮度可用于描述荧光材料。形容词spectral用于区分光谱特性与辐射或发光特性。本报告概述了材料受到辐射时发生的过程，以及材料的特性，这些特性对确定材料的一般行为和少数特殊情况下的行为非常重要。 该报告还澄清了特征和过程的定义。报告有英文、德文和法文版本。它由214页和2个表格组成。

If a material is irradiated, some portion of the incident optical radiation is reflected, another portion absorbed, and a third portion transmitted. This action of a material can be described by the physical, radiant, luminous or spectral characteristics of the material. Fluorescent materials can be described in the same manner but behave as sources for the portion of the radiation which is re-emitted as fluorescence. The terms reflected, transmitted, fluorescent, and total radiance or luminance can be used to describe fluorescent materials. The adjective spectral is used to distinguish spectral properties from radiant or luminous properties.The report is a survey of the processes which occur if a material is irradiated, and of the characteristics of the material which are important in determining its behavior in general and in a few special cases. The report also clarifies the definitions of characteristics and processes.The report is in English, German, and French. It consists of 214 pages and 2 tables.