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Spectral Reflectance



P Y. Barnes, Albert C. Parr, E A. Early


This document describes the instrumentation, standards, and techniques used to measure spectral reflectance over the ultraviolet, visible, and near infrared wavelength ranges. The organization is as follows. Part I describes the motivation for maintaining reference and transfer spectrophotometers for spectral reflectance measurements, the basics of reflection, and the standards and services that are available from NIST. Part II develops the necessary theory of reflection, beginning with basic definitions and equations and ending with the relevant measurement equations for the experiments described in this documentation. The NIST Spectral Tri-function Automated Reference Reflectometer is described in Part III. This instrument provides the basis for the development of absolute NIST standards of diffuse and specular reflectance standards. The transfer instruments rely on master standards that are periodically calibrated on the high accuracy reference reflectometer described in Part III. References containing details are reproduced in the appendices.
Special Publication (NIST SP) - 250-48
Report Number


bidirectional, diffuse reflectance, reflectance, spectral reflectance, spectrophotometer, spectrophotometry, specular reflectance


Barnes, P. , Parr, A. and Early, E. (1998), Spectral Reflectance, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 19, 2024)
Created March 1, 1998, Updated June 2, 2021