NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Spectral responsivity based calibration of photometer and colorimeter standards
Published
Author(s)
George P. Eppeldauer
Abstract
Several new generation transfer- and working-standard illuminance meters and tristimulus colorimeters have been developed at the National Institute of Standards and Technology (NIST) to measure all kinds of light sources with low uncertainty. The spectral and broad-band (illuminance) responsivities of the photometer (Y) channels of two tristimulus meters were determined at both the Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) facility and the Spectral Comparator Facility (SCF). The two illuminance responsivities agreed within 0.1 % with an overall uncertainty of 0.2 % (k=2) which is a factor of two improvement over the present NIST photometric scale. The first detector-based tristimulus color scale was realized. All channels of the reference tristimulus colorimeter were calibrated at the SIRCUS. The other tristimulus meters were calibrated at the SCF and also against the reference meter on the Photometry bench in broad-band measurement mode. The agreement between detector- and source-based calibrations was within 3 K when a tungsten lamp-standard was measured at 2856 K and 3100 K. The color-temperature uncertainty of tungsten lamp measurements was 4 K (k=2) between 2300 K and 3200 K which is a factor of two improvement over the presently used NIST source-based color temperature scale. One colorimeter was extended with an additional (fifth) channel to apply software implemented matrix corrections. With this correction, the spectral mismatch caused color difference errors were decreased by a factor of 20 for single-color LEDs.
Eppeldauer, G.
(2013),
Spectral responsivity based calibration of photometer and colorimeter standards, Journal of Modern Optics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=913528
(Accessed October 12, 2025)