Metrology
Free-Field Reciprocity Calibration of Microphones
pressure calibration by the reciprocity · method. Key words: acoustic calibrations; acoustic measurements; anechoic cham- ber measurements; calibration; free-field · microphone calibration; metrology; mi- crophone calibration; plane-wave free- field acoustic measurements; reciprocity ·
added Oct 30, 2026
Read article →NIST Measurement Services: NIST Calibration Services for Water Flowmeters
The WFCF 3700/100 is used to · provide water flowmeter calibration services as reported in [1] for the Calibration Service · ID Number 18020C. The WFCF 3700/100 uses the static gravimetric method [2] and an · error-free uni-directional diverter with a collection/bypass unit (CB unit) to perform
added Oct 27, 2026
Read article →Calibration of the superconducting gravimeter based on a cold atom absolute gravimeter at NIM
For example, the calibration precision should be better than 1‰ for constraining the Earth tide model or oceanic tide model.[5] In 2017, the 10th International Comparison of Absolute Gravimeters (ICAG-2017) was held at Changping Campus of the National Institute of Metrology (NIM) China.[6] The accur…
added Oct 24, 2026
Read article →Charting the course towards dimensional measurement traceability by X-ray computed tomography | NIST
Here we provide a high-level discussion about traceability of X-ray CT dimensional measurements, review relevant work in understanding X-ray CT measurement uncertainty, and provide a framework for model-based uncertainty assessment and instrument scale calibration as a unified approach to traceabili…
added Oct 22, 2026
Read article →Towards a quantum representation of the ampere using single electron pumps. | NPL Publications
Our pump can generate a current of up to 150 pA, corresponding to almost a billion electrons per second, with an experimentally demonstrated current accuracy better than 1.2 parts per million (ppm) and strong evidence, based on fitting data to a model, that the true accuracy is approaching 0.01 ppm.
added Oct 19, 2026
Read article →Research on volumetric error compensation for NC machine tool based on laser tracker measurement | Request PDF
In this paper, a novel and convenient positioning error measurement approach by utilizing a single laser tracker is proposed followed by two corresponding mathematical models including a laser tracker base point coordinate model and a target mirror coordinates model.
added Oct 16, 2026
Read article →Kilogram: Silicon Spheres and the International Avogadro Project | NIST
For the SI redefinition, several measurements of silicon spheres were used to determine a value of NA at 6.02214076 x 1023 mol-1 (constituents per mole). Provided by scientists in the International Avogadro Coordination, the combined measurements ...
added Oct 14, 2026
Read article →Head to Head: Photonic Pressure Sensors vs. Mercury-Based Standard | NIST
To make the FLOC more accurate than the manometer, the PML team must measure the refractive index of nitrogen at a pressure that is known more accurately than the mercury manometer can currently provide. To get this information, the team is building a device called the variable-length optical cavity…
added Oct 11, 2026
Read article →Realization of the candela | NIST
It is realized using a detector-based method, which is directly traceable to the Division's Reference Cryogenic Radiometer, the Primary Optical Watt Radiometer (POWR), and is maintained on a set of well-characterized filtered detectors, the ...
added Oct 9, 2026
Read article →High-accuracy optical power measurements by using electrical-substitution cryogenic radiometer | Request PDF
At National Metrology Institute of Turkey (UME, Ulusal Metroloji Enstitüsü), luminous intensity unit of candela was realized using detector-based approach and photometric scale was re-established depending on this new realization.
added Oct 6, 2026
Read article →Accurate graphene quantum Hall arrays for the new International System of Units | Nature Communications
The 2019 redefinition of the International System of Units requires a 100 Ω quantum resistance standard for the ideal electrical realization of the kilogram via the Kibble Balance.
added Oct 4, 2026
Read article →Programmable Josephson Voltage Standards and Arbitrary Waveform Synthesizers | NIST
Two of these devices are both well known and trusted by the research and development communities. One is the programmable Josephson voltage standard (PJVS), which generates user-specified DC voltages from -10 V to 10 V.
added Oct 2, 2026
Read article →Primary thermometry - NPL
This offers an alternative temperature measurement technique, enabling calibrations to be traceable to thermodynamic temperature instead of to ITS-90. NPL is using a primary radiometer to measure thermodynamic temperatures of ITS-90 fixed point cells over the range from ~232 °C up to ~1085 °C. ...
added Sep 26, 2026
Read article →Interferometers calibrate gauge blocks over optical fiber | Laser Focus World
They are "among the most commonly used standards for maintaining traceability in dimensional metrology," according to an online description by Britain's National Physical Laboratory (Middlesex, England).1 Yet even at this year's annual meeting ...
added Sep 24, 2026
Read article →Towards the optical second: verifying optical clocks at the SI limit - PMC
The pursuit of ever more precise measures of time and frequency motivates redefinition of the second in terms of an optical atomic transition. To ensure continuity with the current definition, based on the microwave hyperfine transition in 133Cs, it ...
added Sep 22, 2026
Read article →Kilogram: Mass and Planck's Constant | NIST
In 1999, in a letter published in the journal Metrologia, they proposed assigning a fixed value to the Planck constant as the basis for a new kilogram definition. Mohr and Taylor explored the use of a Kibble balance, a complex device that measures ...
added Sep 20, 2026
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