Journal•ISSN: 0026-1394
Metrologia
IOP Publishing
About: Metrologia is an academic journal published by IOP Publishing. The journal publishes majorly in the area(s): Calibration & Metrology. It has an ISSN identifier of 0026-1394. Over the lifetime, 5408 publications have been published receiving 88726 citations.
Topics: Calibration, Metrology, Measurement uncertainty, Laser, Radiometer
Papers published on a yearly basis
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TL;DR: The International Temperature Scale of 1990 as mentioned in this paper was adopted by the International Committee of Weights and Measures at its meeting in 1989, in accordance with the request embodied in Resolution 7 of the 18th General Conference of WEMS of 1987.
Abstract: The International Temperature Scale of 1990 was adopted by the International Committee of Weights and Measures at its meeting in 1989, in accordance with the request embodied in Resolution 7 of the 18th General Conference of Weights and Measures of 1987. This scale supersedes the International Practical Temperature Scale of 1968 (amended edition of 1975) and the 1976 Provisional 0.5 K to 30 K Temperature Scale.
1,412 citations
TL;DR: In this article, the authors presented an improved dispersion formula for standard air, (n − 1)s × 108 = 8342, where σ is the vacuum wave-number in μm-1.
Abstract: Present knowledge of the refractive index of air is reviewed. Regarding the absolute values there are as yet no definite indications that the standard adopted in 1953 on the basis of Barrell and Sears' measurements should be changed, but new experiments aiming at reducing the present uncertainty of about ± 5 × 10-8 would be desirable. Several recent investigations have contributed important new information on the dispersion of air, which has made it possible to derive an improved dispersion formula for standard air, (n − 1)s × 108 = 8342.13 + 2406030 (130 − σ2)-1 + 15997 (38.9 − σ2)−1, where σ is the vacuum wave-number in μm-1. The deviations from the 1953 formula are small and practically negligible in most spectroscopic work. An equation for the dependence of refractivity on temperature and pressure based on theoretical considerations has been derived. For the range of atmospheric conditions normally found in a laboratory the equation can be approximated by the formula (n − 1)tp = (n − 1)s × 0.00138823 p/(1 + 0.003671 t), with p in torr, t in °C, and (n − 1)s given by the dispersion formula for standard air. The effect of carbon dioxide and water vapour is discussed. From Erickson's dispersion data for water vapour, combined with Barrell and Sears' absolute measurements, one obtains the equation ntpf – ntp = −f (5.722 − 0.0457 σ2) × 10-8 for the difference in refractive index of moist air, containing f torr of water vapour, and dry air at equal temperature and total pressure. The equation is valid for visible radiations and normal atmospheric conditions.
1,229 citations
TL;DR: In this article, an atom interferometer that can measure g, the local acceleration due to gravity, with a resolution of Δg/g = 2 × 10−8 after a single 1.3 s measurement cycle was built.
Abstract: We have built an atom interferometer that can measure g, the local acceleration due to gravity, with a resolution of Δg/g = 2 × 10−8 after a single 1.3 s measurement cycle, 3 × 10−9 after 1 min and 1 × 10−10 after two days of integration time. The difference between our value for g and one obtained by a falling corner-cube optical interferometer is (7 ± 7) × 10−9 g. The atom interferometer uses velocity-selective stimulated Raman transitions and laser-cooled caesium atoms in an atomic fountain. We extend previous methods of analysing the interferometer to include the effects of a gravitational gradient. We also present detailed experimental and theoretical studies of potential systematic errors and noise sources.
775 citations
TL;DR: The agreement between calculation and experiment within an experimental uncertainty of ± 3 × 10-8 was established in this paper. But the agreement was only for the case where the carbon dioxide content of normal laboratory air has increased.
Abstract: The Edlen equation for the refractive index of air, published in 1966, is still widely used. Subsequent to its formulation, however, improved data have become available on the density of air and the refractivity of water vapour. The practical temperature scale has also been revised and the carbon dioxide content of normal laboratory air has increased. These effects result in a discrepancy of typically 1 × 10-7. The consequent revision of the equation brings the agreement between calculation and experiment within an experimental uncertainty of ± 3 × 10-8.
503 citations
TL;DR: The design improvements incorporated in a new generation of absolute gravimeters, the FG5, have led to an instrumental uncertainty estimate of 1,1 × 10-8 m s-2 (1,0 μGal).
Abstract: We describe the design improvements incorporated in a new generation of absolute gravimeters, the FG5. A vertically oriented (in-line) interferometer design is used to remove the influence of floor vibration and tilt on the optical path length. The interferometer uses an iodine-stabilized laser as a primary length standard, with circuitry for automatic peak detection and locking. The seismic isolation system is an active long-period seismometer (Super Spring). The new design has improved passive isolation and thermal drift characteristics over previous systems. Programming flexibility and control of the test mass trajectory have been improved. The computer system has also improved real-time analysis and system capability. The FG5 instrument has a higher level of robustness, reliability and ease of use. These design advances have led to an instrumental uncertainty estimate of 1,1 × 10-8 m s-2 (1,0 μGal). Instrument agreement among nine similar devices is 1,8 μGal and observations under optimal conditions exhibit standard deviations of 5 μGal to 8 μGal.
496 citations