1.1 本规程涵盖了制备压制粉末转移标准的程序。这些标准可用于电磁频谱的近紫外、可见光和近红外区域。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 ( 2. ) . 压制粉末标准被用作此类校准的传输标准，因为它们具有高反射系数，几乎与波长恒定，并且反射通量的几何分布类似于完美反射扩散器的几何分布。 1.2 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 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====== 5.1 所有商用反射计都测量相对反射率。仪器读数是反射系数，即参考试样反射的光与试样反射的光的比率。该比率取决于特定的仪器参数。 5.2 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 ( 2. ) . 这些测量非常困难，通常由专业实验室进行。 5.3 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，尤其是与反射光的几何分布相关的性能。 因此，足够坚固且能够清洁的反射因子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。 5.4 来自压制粉末斑块的反射辐射的几何分布具有足够的漫反射性，可以为定向半球反射计提供可靠的校准。尽管压制粉末标准品会受到污染和破坏，但压制粉末标准品的定向半球反射系数可以在由给定批次粉末制成的样品之间充分再现，以便允许将绝对反射系数值分配给批次中的所有粉末。 5.5 本规程描述了如何从粉末中制备白色反射率因子标准，使标准化实验室能够将反射率的绝对比例分配给斑块。 注1: 压粉前，应将套环和容器牢固固定到位。

1.1 This practice covers procedures for preparing pressed powder transfer standards. These standards can be used in the near-ultraviolet, visible and near-infrared region of the electromagnetic spectrum. Procedures for calibrating the reflectance factor of materials on an absolute basis are contained in CIE Publication No. 44 ( 2 ) . Pressed powder standards are used as transfer standards for such calibrations because they have a high reflectance factor that is nearly constant with wavelength, and because the geometric distribution of reflected flux resembles that from the perfect reflecting diffuser. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 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 ====== 5.1 All commercial reflectometers measure relative reflectance. The instrument reading is the reflectance factor, the ratio of the light reflected by a reference specimen to that reflected by a test specimen. That ratio is dependent on specific instrument parameters. 5.2 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 ( 2 ) . These measurements are sufficiently difficult that they are usually left to laboratories that specialize in them. 5.3 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 optical properties, especially those properties related to the geometric distribution of the reflected light. Thus, reflectance factor standards which are sufficiently rugged and able to be cleaned, depart considerably from the perfect diffuser in the geometric distribution of reflected radiance. 5.4 The geometric distribution of reflected radiance from a pressed powder plaque is sufficiently diffuse to provide a dependable calibration of a directional-hemispherical reflectometer. Although pressed powder standards are subject to contamination and breakage, the directional-hemispherical reflectance factor of pressed powder standards can be sufficiently reproducible from specimen to specimen made from a given lot of powder, so as to allow one to assign absolute reflectance factor values to all the powder in a lot. 5.5 This practice describes how to prepare white reflectance factor standards from a powder in a manner that allows a standardizing laboratory to assign the absolute scale of reflectance to the plaque. Note 1: The collar and receptacle should be securely held in place before pressing the powder.