### Abstract

^{–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 language | English |
---|---|

Pages (from-to) | 2400-2409 |

Number of pages | 10 |

Journal | Optical Engineering |

Volume | 43 |

Issue number | 10 |

DOIs | |

Publication status | Published - 2004 |

MoE publication type | A1 Journal article-refereed |

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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.

Research output: Contribution to journal › Article › Scientific › peer-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

Y1 - 2004

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

DO - 10.1117/1.1787834

M3 - Article

VL - 43

SP - 2400

EP - 2409

JO - Optical Engineering

JF - Optical Engineering

SN - 0091-3286

IS - 10

ER -