Re-Analysis of the Uncertainty of the 0.895 mm Diameter (NIST SRMRG 1690) and the 0.269 mm Diameter (NIST SRMRG 1691) Sphere Standards.
Re-Analysis of the Uncertainty of the 0.895 mm Diameter
(NIST SRMRG 1690) and the 0.269 mm Diameter (NIST SRMRG
1691) Sphere Standards.
(523 K)
Mulholland, G. W.
Journal of Research of the National Institute of
Standards and Technology, Vol. 110, No. 1, 27-30,
January/February 2005.
Keywords:
standards; uncertainty; light scattering; Mie
Scattering; polystyrene spheres; Standard Reference
Materials; transmission electron microscopy
Abstract:
The uncertainties of the mean diameters of the nominal
1.0 mm SRMRG 1690 polystyrene spheres and of the nominal
0.3 mm SRMRG 1691 polystyrene spheres are recomputed
using the current NIST Guidelines for computing
uncertainty. The revised expanded uncertainty
(approximately 95% confidence level) for SRMRG 1690
polystyrene spheres is equal to 0.005 mm compared to
previous value of 0.008 mm. The revised expanded
uncertainty for SRMRG 1691 is equal to 0.004 mm compared
to the previous value of 0.007 mm. The major cause of
the reduction in the uncertainty for the 1.0 mm spheres
is from a decrease in the recomputed uncertainty of the
refractive index of the polystyrene spheres. The 1.0 mm
spheres were used in calibrating the electron microscope
used to size the 0.3 mm spheres, and the reduction in
the uncertainty of 1.0 mm SRMRG uncertainty was the
biggest factor in the decrease in the uncertainty of the
0.3 mm spheres.
