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.
Report on the SIM Photometry and Radiometry Key Comparison of Spectral Regular Transmittance (SIM.PR-K6.2010)
Published
Author(s)
Catherine Cooksey, Blaza Toman
Abstract
This report details the results of the Inter-American Metrology System (SIM) key comparison on regular spectral transmittance (SIM.PR-K6.2010). Eight national metrology institutes participated in the comparison, which covered the spectral range from 380 nm to 1000 nm and the nominal transmittance range from 0.1 % to 90 % transmittance. The protocol mirrored that of the key comparison conducted by the Consultative Committee on Photometry and Radiometry (CCPR-K6.2010). The National Institute of Standards and Technology (NIST) served as the pilot. Each participant received a single set of 5 comparison (neutral density) filters to measure. The pilot measured all sets before and after the participant measurements. All measurements were completed between December 2016 and February 2018. The results of this comparison were linked to the key comparison reference value (KCRV) of the CCPR comparison and are expressed in terms of degrees of equivalence. While most of the participants can adequately measure spectral regular transmittance and evaluate its uncertainty, there are some cases of non-equivalence that will require further investigation on the part of the participants.
Cooksey, C.
and Toman, B.
(2021),
Report on the SIM Photometry and Radiometry Key Comparison of Spectral Regular Transmittance (SIM.PR-K6.2010), Metrologia, [online], https://doi.org/10.1088/0026-1394/58/1A/02004, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932585
(Accessed October 9, 2025)