The NIST Standard
The NIST standard is published by the National Institute of Science and Technology. The NIST was founded in 1901 and is one of the oldest laboratories in the United States. First known as the Office of Weights and Measures and then National Bureau of Standards. Today it is known as the National Institute of Science and Technology (NIST). It part of the U.S. Department of Commerce. For more information: https://www.nist.gov/about-nist.
NIST’s vision
“NIST will be the world’s leader in creating critical measurement solutions and promoting equitable standards. Our efforts stimulate innovation, foster industrial competitiveness, and improve the quality of life.”1
How is the NIST Important?
Try to imagine the problems that occurred if countries around the world use a different measurement for the number 4. Today having an internationally accepted standard for measuring UV light for each wavelength is a tangible baseline established and accepted by countries all around the world. The NIST Standard provides users of UV light with a common denominator. The value of 4 mw/cm2 at 365nm is the same whether in South Korea, USA, UK, South Africa or India.
Why is the NIST Important?
Repeatability, repeatability, repeatability! Any instrument requiring calibration needs a baseline number. This number has to be calculable, measureable, repeatable and available to all UV Light Meters manufacturers and UV light users. The NIST standard provide these parameters. Light meters used daily, weekly or even monthly need to be calibrated, preferably on a yearly basis. Through use, wirers break, glass stacks get cracked or dirty, and some component may degrade or even fail. Therefore, they need to be re-calibrated but to a known baseline number no matter where in world or who the manufacturer is. Also, the accuracy of the lab doing the calibration has to be considered. Therefore, accuracy and repeatability to the NIST standard should be the “hallmarks” for UV Light Meters. However, even with the NIST standard, some companies manufacturing UV Light Meters either use their own “in-house” standard or no standard at all.
1. https://www.nist.gov/about-nist.