本文件涉及使用双光束扫描分光光度计测定平面透明塑料和基本无色塑料在光谱可见区域的总透光率。本文件不适用于含有荧光材料的塑料。 本文件适用于厚度不超过10？mm的透明模塑材料、薄膜和薄板。 注1:总光透射率也可通过ISO 13468-1中的单光束仪器测定。 注？2？基本无色的塑料包括浅色的塑料。 注3:如果仪器能够容纳厚度超过10毫米的试样，则可以对其进行测量，但结果不能与使用厚度小于10毫米的试样获得的结果进行比较。

This document covers the determination of the total luminous transmittance, in the visible region of the spectrum, of planar transparent plastics and substantially colourless plastics, using a double-beam scanning spectrophotometer. This document cannot be used for plastics which contain fluorescent materials. This document is applicable to transparent moulding materials, films and sheets not exceeding 10？mm in thickness. NOTE？1？Total luminous transmittance can also be determined by a single-beam instrument as in ISO？13468-1. NOTE？2？Substantially colourless plastics include those which are faintly tinted. NOTE？3？Specimens more than 10？mm thick can be measured provided the instrument can accommodate them, but the results cannot be comparable with those obtained using specimens less than 10？mm thick.