1.1本规程涵盖了近红外分光光度计可接受转移标准的制备和使用程序。在绝对基础上校准材料反射系数的程序包含在CIE第44号出版物中 (9) . 压制粉末样品和烧结PTFE材料都用作此类校准的传输标准，因为它们具有非常稳定的反射系数，几乎随波长恒定，并且通量分布与完美反射扩散器的通量分布非常相似。 1.2以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 大多数具有反射能力的商用反射计和分光光度计测量相对反射率。仪器读数是参考样本反射的测量辐射与试样反射的测量辐射的比率。该比率取决于特定的仪器参数。 国家标准化实验室和一些研究实验室测量根据基本原理校准的仪器的反射率，从而建立CIE第44号出版物中所述的绝对反射率标度 (5) . 这些测量非常困难，而且成本高昂，因此通常由专业实验室进行测量。 在绝对刻度上测量的标准可用于将该刻度转换为反射计。虽然存在此类程序，但对机械性能的约束限制了某些光学性能的适用性，尤其是与反射辐射的几何分布相关的性能。 因此，除了烧结PTFE标准外，足够坚固或可清洁以用作永久传输标准的反射系数标准在反射辐射的几何分布上与完美的扩散器有很大的不同。 来自此类标准的反射辐射的几何分布具有足够的漫反射性，因此此类标准可以为定向半球反射计或某些定向反射计提供可靠的校准。尽管压制粉末标准会受到污染和破坏，但压制粉末的反射系数可以在给定批次粉末的不同样本之间充分再现，以允许将绝对反射系数值分配给批次中的所有粉末。 在重新表面处理或清洁试样后，烧结PTFE材料在同一试样内表现出足够的再现性，以允许分配绝对反射率因子值。 规程E 259涵盖了包装粉末反射率标准的制备 . 本规程描述了这些材料和烧结PTFE材料的光谱和物理特性。

1.1 This practice covers procedures for the preparation and use of acceptable transfer standards for NIR spectrophotometers. Procedures for calibrating the reflectance factor of materials on an absolute basis are contained in CIE Publication No. 44 (9) . Both the pressed powder samples and the sintered PTFE materials are used as transfer standards for such calibrations because they have very stable reflectance factors that are nearly constant with wavelength and because the distribution of flux resembles closely that from the perfect reflecting diffuser. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== Most commercial reflectometers and spectrophotometers with reflectance capability measure relative reflectance. The instrument reading is the ratio of the measured radiation reflected from the reference specimen to the measured radiation reflected by the test specimen. That ratio is dependent on specific instrument parameters. National standardizing laboratories and some research laboratories measure reflectance on instruments calibrated from basic principles, thereby establishing a scale of absolute reflectance as described in CIE Publication No. 44 (5) . These measurements are sufficiently difficult and of prohibitive cost that they are usually left to laboratories that specialize in them. A standard that has been measured on an absolute scale could be used to transfer that scale to a reflectometer. While such procedures exist, the constraints placed on the mechanical properties restrict the suitability of some of the optical properties, especially those properties related to the geometric distribution of reflected radiation. Thus, reflectance factor standards that are sufficiently rugged or cleanable to use as permanent transfer standards, with the exception of the sintered PTFE standards, depart considerably from the perfect diffuser in the geometric distribution of reflected radiation. The geometric distribution of reflected radiance from such standards is sufficiently diffuse that such a standard can provide a dependable calibration of a directional-hemispherical or certain directional-directional reflectometers. Although pressed powder standards are subject to contamination and breakage, the reflectance factor of pressed powder can be sufficiently reproducible from specimen to specimen from a given lot of powder to allow the assignment of absolute reflectance factor values to all of the powder in a lot. Sintered PTFE materials exhibit sufficient reproducibility from within the same specimen after resurfacing or cleaning the specimen to allow the assignment of absolute reflectance factor values. Preparation of packed powder reflectance standards is covered in Practice E 259 . This practice describes the spectral and physical properties of these materials and of the sintered PTFE materials.