The Candela and Photometric and Radiometric Measurements

Published

January 1, 2001

Author(s)

Albert C. Parr

Abstract

The national measurement system for photometric and radiometric quantities is presently based upon techniques and a measurement chain that make these quantities traceable to a high accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of most photometric and radiometric quantities upon absolute detector based technology as was envisioned by the 1979 redefinition. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements.

Citation

Journal of Research (NIST JRES) -

Volume

106 No. 1

NIST Pub Series

Journal of Research (NIST JRES)

Pub Type

NIST Pubs

Keywords

laser power, photometry, radiation temperature, radiometric, standards

Citation

Parr, A. (2001), The Candela and Photometric and Radiometric Measurements, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD (Accessed July 4, 2025)