Acoustic method for determination of the effective temperature and refractive index of air in accurate length interferometry

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Abstract

An acoustic method for the measurement of the effective temperature and refractive index of air for precision length interferometry is described. The method can be used to improve the accuracy of interferometric length measurements outside the best laboratory conditions and also in industrial conditions. The method is based on the measurement of speed of 50-kHz ultrasound over the same distance measured with a laser interferometer. The measured speed of ultrasound is used to define the effective temperature or the refractive index of air along the laser beam path using the equations presented. The measured speed of sound, Cramer equation, dispersion correction, and Edlén equations are used in the fitting of new equations for the effective air temperature and refractive index of air as a function of speed of 50-kHz ultrasound. The standard uncertainties of the effective temperature and the refractive index of air equations are 15 mK and 1.7×10–8, respectively. The uncertainties of the effective temperature and refractive index of air measured with the test setup for distances of about 5 m are 25 mK and 2.6×10–8, respectively.
Original languageEnglish
Pages (from-to)2400-2409
Number of pages10
JournalOptical Engineering
Volume43
Issue number10
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

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Interferometry
Refractive index
interferometry
Acoustics
refractivity
acoustics
air
Air
Ultrasonics
Temperature
temperature
Acoustic wave velocity
Interferometers
Laser beams
interferometers
laser beams
Lasers
lasers

Cite this

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title = "Acoustic method for determination of the effective temperature and refractive index of air in accurate length interferometry",
abstract = "An acoustic method for the measurement of the effective temperature and refractive index of air for precision length interferometry is described. The method can be used to improve the accuracy of interferometric length measurements outside the best laboratory conditions and also in industrial conditions. The method is based on the measurement of speed of 50-kHz ultrasound over the same distance measured with a laser interferometer. The measured speed of ultrasound is used to define the effective temperature or the refractive index of air along the laser beam path using the equations presented. The measured speed of sound, Cramer equation, dispersion correction, and Edl{\'e}n equations are used in the fitting of new equations for the effective air temperature and refractive index of air as a function of speed of 50-kHz ultrasound. The standard uncertainties of the effective temperature and the refractive index of air equations are 15 mK and 1.7×10–8, respectively. The uncertainties of the effective temperature and refractive index of air measured with the test setup for distances of about 5 m are 25 mK and 2.6×10–8, respectively.",
author = "Virpi Korpelainen and Antti Lassila",
year = "2004",
doi = "10.1117/1.1787834",
language = "English",
volume = "43",
pages = "2400--2409",
journal = "Optical Engineering",
issn = "0091-3286",
publisher = "International Society for Optics and Photonics SPIE",
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}

Acoustic method for determination of the effective temperature and refractive index of air in accurate length interferometry. / Korpelainen, Virpi; Lassila, Antti.

In: Optical Engineering, Vol. 43, No. 10, 2004, p. 2400-2409.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Acoustic method for determination of the effective temperature and refractive index of air in accurate length interferometry

AU - Korpelainen, Virpi

AU - Lassila, Antti

PY - 2004

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N2 - An acoustic method for the measurement of the effective temperature and refractive index of air for precision length interferometry is described. The method can be used to improve the accuracy of interferometric length measurements outside the best laboratory conditions and also in industrial conditions. The method is based on the measurement of speed of 50-kHz ultrasound over the same distance measured with a laser interferometer. The measured speed of ultrasound is used to define the effective temperature or the refractive index of air along the laser beam path using the equations presented. The measured speed of sound, Cramer equation, dispersion correction, and Edlén equations are used in the fitting of new equations for the effective air temperature and refractive index of air as a function of speed of 50-kHz ultrasound. The standard uncertainties of the effective temperature and the refractive index of air equations are 15 mK and 1.7×10–8, respectively. The uncertainties of the effective temperature and refractive index of air measured with the test setup for distances of about 5 m are 25 mK and 2.6×10–8, respectively.

AB - An acoustic method for the measurement of the effective temperature and refractive index of air for precision length interferometry is described. The method can be used to improve the accuracy of interferometric length measurements outside the best laboratory conditions and also in industrial conditions. The method is based on the measurement of speed of 50-kHz ultrasound over the same distance measured with a laser interferometer. The measured speed of ultrasound is used to define the effective temperature or the refractive index of air along the laser beam path using the equations presented. The measured speed of sound, Cramer equation, dispersion correction, and Edlén equations are used in the fitting of new equations for the effective air temperature and refractive index of air as a function of speed of 50-kHz ultrasound. The standard uncertainties of the effective temperature and the refractive index of air equations are 15 mK and 1.7×10–8, respectively. The uncertainties of the effective temperature and refractive index of air measured with the test setup for distances of about 5 m are 25 mK and 2.6×10–8, respectively.

U2 - 10.1117/1.1787834

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SN - 0091-3286

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