This uncertainty in measurement is only a couple of picometers
' worth but is extremely important for scientists who need very precise measurements.
For step heights, measurement uncertainties in the subnanometer range - and for measurements of the mean structure spacing on extensive lattice standards even in the range of 10 picometers
- have been achieved and confirmed in comparison with optical diffraction measurements.The new measuring instrument is available for dimensional precision measurements with nm resolution on 3D micro and nano structures such as micro gears, micro balls, hardness indenters and nano lattice standards as well as for comparisons of measures; moreover, it serves as a platform for research and development tasks.
The electro-optic coefficient(, a figure representing the level of change in the refractive index, was verified as being 76 picometers
per volt (76pm/V) with infrared light.
After modifying the noise signal amplitudes (so they were less than the FEM signal amplitudes) and changing the units to picometers
, the signals were examined to determine their consistency.
It was found that the "stabilized" FBGs actually drift slightly with time (a few picometers
After modifying the signal amplitudes ([S.sub.0] they were less than the FEM signal amplitudes) and changing the units to picometers
, the noise signals were examined to determine their consistency.
The unit provides eight calibration references between 1297 nm and 1306 nm and 12 references between 1531 nm and 1550 nm, each with a stability of a few picometers
. NIST scientists are now investigating methods to incorporate calibration references in the 850 nm region.