Verification of Revised Water Vapour Correction to the Index of Refraction of Air

Beers, John S.; Doiron, Theodore D.

doi:10.1088/0026-1394/29/4/008

Cited by 21 publications

(15 citation statements)

References 5 publications

(2 reference statements)

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“…[5][6][7] Yet the applicable experimental results in the windows around 3.5, 4.8, and 10 m reduce to merely two measurements 8,9 at wavelengths of ϭ 3.4 and 10.6 m and one 10 at 28 m that does not allow easy separation of water and dry air. The majority of associated data in the literature extends wavelength coverage by extrapolation of mid-IR or visible [11][12][13] spectra. Another tempting extrapolation of liquidwater data 14 -18 by Clausius-Mossotti-͑Lorentz-Lorenz-͒ type density scaling is challenged to account for the strong permanent dipole moment of the water molecules.…”

Section: Scopementioning

confidence: 99%

Calculated refractivity of water vapor and moist air in the atmospheric window at 10 μm

Mathar

2004

Appl. Opt.

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The HITRAN 2000 database of infrared line transitions has been used to calculate the dispersion coefficient of water vapor at room temperature in the atmospheric window up to 25 microm, confirming an equivalent earlier compilation [Infrared Phys. 26, 371 (1986)]. I complement this line set by using an previously published ultraviolet pseudospectrum [J. Chem. Phys. 68, 1426 (1978)] to improve coverage of the near infrared. The effect of admixtures of abundant nitrogen, oxygen, and carbon dioxide is predicted on the same calculational basis to synthesize the air representative of the mountain that hosts the Very Large Telescope Interferometer and is found to be small compared with the dominant role of water at wavelengths above 3 microm.

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Section: Scopementioning

confidence: 99%

Calculated refractivity of water vapor and moist air in the atmospheric window at 10 μm

Mathar

2004

Appl. Opt.

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“…Until 1991 the refractive index of air was computed from Edlén 1966 equation [ 13 ]. Birch and Downs [ 14 ] recently developed a modified form of the equation that provides significant improvement in uncertainty [ 15 ]. The changes are mainly in the correction for air moisture and in values for CO 2 content of air.…”

Section: The Nist Length Scale Interferometermentioning

confidence: 99%

“…Indirect testing of the revised correction was done at NIST by measuring control standard M5727 with the line scale interferometer over a range of partial pressure of water vapor in air from 467 Pa to 1167 Pa (20 % to 55 % r.h. at 20 °C). These measurements were made as part of this study of systematic effects but results were published separately [ 15 ].…”

Section: Measurement Assurancementioning

confidence: 99%

The NIST length scale interferometer

Beers¹,

Penzes²

1999

J. Res. Natl. Inst. Stand. Technol.

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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.

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“…The indirect method is to measure the parameters of the air composition through various sensors, such as ambient temperature, humidity, air pressure and so on. The refractive index value is calculated in order to obtain the air refractive index formula [4][5][6][7][8][9][10][11][12]. The important characteristic of the indirect measurement method is that it is convenient and easy to use.…”

Section: Introductionmentioning

confidence: 99%

A Real-Time Measurement Method of Air Refractive Index Based on Special Material Etalon

Ren

Ding

2018

Applied Sciences

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In the precise displacement measurement based on laser interferometry, the measurement technology for the refractive index of air is widely used to improve the measurement accuracy. However, the existing measurement method of the refractive index of air based on direct measurement is not easy to realize in practical work because of its complex measurement principle and the huge volume of the measurement device; while the measurement accuracy and speed based on the indirect method cannot adapt to the real-time, fast and accurate measurement requirements of industrially changing environments, resulting in distortion of the results. In this study, a measurement method of the refractive index of air based on a special material etalon is proposed. The method enables rapid and direct measurement of the air refractive index when the environment changes and it is given the realization process. Finally, the experimental results show that the deviation between this method and the modified Edlen formula is about 2.5 × 10 −7 , and that this method can quickly reflect the changes of the environment, which prove the correctness of this method and its ability manage rapid environmental responses. This method is worth popularizing in industrial measurement.

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Verification of Revised Water Vapour Correction to the Index of Refraction of Air

Cited by 21 publications

References 5 publications

Calculated refractivity of water vapor and moist air in the atmospheric window at 10 μm

Calculated refractivity of water vapor and moist air in the atmospheric window at 10 μm

The NIST length scale interferometer

A Real-Time Measurement Method of Air Refractive Index Based on Special Material Etalon

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