Method and apparatus for the measurement of the refractive index of a gas
US4685803A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 23, 1986 |
| Grant date | Aug 11, 1987 |
| Priority date | — |
| Expiry date | Jan 23, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/45
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical apparatus capable of measuring the absolute refractive index of a gas is provided which comprises: (1) an evacuated cell (50) comprised, most preferably, of a bellows (52) with transparent plano windows (41, 61) which have diameters larger than the outside diameter of said bellows (52) attached to each end of said bellows (52); (2) means, most preferably, high reflectivity mirror coating spots (46, 47, 66, 67), for obtaining reflections from the surfaces on the vacuum sides of said windows (41, 61); (3) means for varying the distances between said high reflectivity mirror coatings from less than a few micrometers to approximately 100 millimeters; (4) means, most preferably a first differential plane mirror interferometer (23) with its measurement leg in the gas to be measured outside of the vacuum cell (50); means, most preferably a second differential plane mirror interferometer (33) with its measurement leg in the vacuum cell (50); (6) means, for measuring the first phase variation (73, 75, 77) in said first differential plane mirror interferometer (23) as said distance varies from zero to approximately 100 milimeters; (7) means, for measuring the second phase variatio…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.