Apparatus for the measurement of the refractive index of a gas
US4733967A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 19, 1987 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Mar 19, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/45
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus capable of measuring either changes in the refractive index, or, if desired, the absolute refractive index, of a gas is provided which comprises a differential plane mirror interferometer to produce a pair of measurement beams and a pair of reference beams; and a gas-tight refractive index cell means (78) comprised, most preferably, of a window (70) affixed to the end of a cylindrical tube (73) closest to the interferometer and a mirror (75) affixed to the other end of the tube (73), the cell (78) being aligned to the interferometer so that the reference beams pass inside of the tube (73) in a sealed volume and the measurement beams pass outside of the tube (73), such as in ambient air, for the measurement of changes in the refractive index of the gas surrounding the gas-tight cell (78). When the absolute refractive index of a gas is to be measured, the gas-tight cell (78) comprises, most preferably, a window (70) affixed to the ends of a pair of cylindrical concentric tubes (73, 86) closest to the interferometer and a mirror (75) affixed to the other ends of the tubes (73, 86) to provide two sealed volumes, with the cell (78) being aligned to the interferometer so that t…
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