The National Cooperative Highway Research Program (NCHRP Project 05-16) awarded The National Institute of Standards and Technology (NIST) a contract to develop a dedicated reference instrument for measuring retroreflective materials, and a calibration program that provides traceability to the relevant national scales maintained by NIST. The most critical aspect of the NIST Reference Retroreflectometer is the absolute alignment of the three components: thesource, the goniometer, and the detector. Presented are the methods for aligning the components and the uncertainty of the four angles defined as the CIE goniometer system. The expanded uncertainty (k=2) for the observation angle, alpha, is 0,00057 ; for the entrance angle components, beta 1 and beta 2, is 0,0090 ; and for the rotation angle, epsilon, is 0,061 .
Proceedings Title: Commission Internationale de L'eclairage | 25th | | CIE
Conference Dates: June 25-July 2, 2003
Conference Title: Publications Commission Internationale De L'Eclairage CIE
Pub Type: Conferences
calibration standard, retroreflection, retroreflectometer, uncertainty