Re-Analysis of the Uncertainty of the 0.895 [mu]m Diameter (NIST SRM[Trademark] 1690) and the 0.269 [mu]m Diameter (NIST SRM[Trademark] 1691) Sphere Standards
George W. Mulholland
The uncertainties of the mean diameters of the 1.0 micrometer SRM 1690 polystyrene spheres and of the 0.3 micrometer SRM 1691 polystyrene spheres are recomputed using the current NIST Guidelines for computing uncertainty. The revised expanded uncertainty (approximately 95 % confidence level) for SRM 1690 polystyrene spheres is equal to 0.005 micrometer compared to previous value of 0.008 micrometer. The revised expanded uncertainty for SRM 1691 is equal to 0.004 micrometer compared to the previous value of 0.007. The major cause of the reduction in the uncertainty for the 1.0 micrometer spheres is from a decrease in the recomputed uncertainty of the refractive index of the polystyrene spheres. The 1.0 micrometer spheres were used in calibrating the electron microscope used to size the 0.3 micrometer spheres, and the reduction in the uncertainty of 1.0 micrometer SRM uncertainty was the biggest factor in the decrease in the uncertainty of the 0.3 micrometer spheres.
Re-Analysis of the Uncertainty of the 0.895 [mu]m Diameter (NIST SRM[Trademark] 1690) and the 0.269 [mu]m Diameter (NIST SRM[Trademark] 1691) Sphere Standards, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=861336
(Accessed December 5, 2023)