The results of a comparison between calculated and measured values of the refractive index of air
- 1 July 1988
- journal article
- Published by IOP Publishing in Journal of Physics E: Scientific Instruments
- Vol. 21 (7) , 694-695
- https://doi.org/10.1088/0022-3735/21/7/015
Abstract
When optical techniques are applied to high-accuracy length measurement in the free atmosphere it is essential to apply a correction for the refractive index of the air. This can be obtained either by calculation using Edlen's equation or by direct measurement using a gas refractometer. An investigation of the accuracy achievable using Edlen's equation has been made using a high-precision interference gas refractometer developed at the NPL. The results have shown that a correction to the water vapour term in Edlen's equation is required to achieve the highest accuracy.Keywords
This publication has 5 references indexed in Scilit:
- The measurement of humidity variations in gases resulting from the adsorption of water on to surfacesJournal of Physics E: Scientific Instruments, 1988
- Optical path length changes induced in cell windows and solid etalons by evacuationJournal of Physics E: Scientific Instruments, 1988
- Bi-directional fringe counting interference refractometerPrecision Engineering, 1983
- The Refractive Index of AirMetrologia, 1966
- The refraction and dispersion of air and dispersion of air for the visible spectrumPhilosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1939