The NIST length scale interferometer

Abstract

The National Institute of Standards and Technology (NIST) interferometer for measuring graduated length scales has been in use since 1965. It was developed in response to the redefinition of the meter in 1960 from the prototype platinum-iridium bar to the wavelength of light. The history of the interferometer is recalled, and its design and operation described. A continuous program of modernization by making physical modifications, measurement procedure changes and computational revisions is described, and the effects of these changes are evaluated. Results of a long-term measurement assurance program, the primary control on the measurement process, are presented, and improvements in measurement uncertainty are documented.

Certification of New Standard Reference Material 2806b Medium Test Dust in Hydraulic Oil

“…A Geller MRS-4XY scanning electron microscope 10 × to 50,000 × pitch standard was made traceable to the SI by means of the NIST Line Scale Interferometer (LSI) [3,4]. W. B. Penzes, NIST Precision Engineering Division (683) did the measurements.…”

“…The diameters are made traceable to the NIST Line Scale Interferometer (LSI) through a NIST calibration of a Geller MRS-4XY pitch standard [3,4]. The certified diameters are correlated with the numeric concentration of particles greater than each diameter, referred to as the cumulative number size distribution.…”

“…(2) An experimental design was developed through the NIST Statistical Engineering Division to determine the number of bottles to be analyzed. (3) NIST designed multiple statistical tests coded in DATAPLOT [5,6] to assure the production process of SRM 2806b produced a high quality material. (4) Material homogeneity measurements were made with laser-based extinction particle counters and statistical tests designed by NIST.…”

Line scale measurement using image registration

“…This type of measurement requires that line scales are calibrated with high accuracy level. In the last two decades National Institutes of Metrology have been developing research on line scale measurement in order to meet this requirement [1][2][3][4], However, these researches have the purpose of reducing the measurement uncertainty through improvements in displacement measuring systems or through error compensation of movement systems and not exactly by using image processing techniques. In such systems, these techniques are used only for identification of the markings throughout the scale, not to extract measurements.…”

Measurement Uncertainty Evaluation of the Null Detector Method Using Monte Carlo

“…The measurements may vary in accuracy from tenth of a millimeter [2] to a couple of nanometers [3,4].…”