Spectroscopic method and apparatus
US5913234A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1997 |
| Grant date | Jun 15, 1999 |
| Priority date | — |
| Expiry date | Oct 20, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/1702
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for determining the concentration of a substance of interest by gas-coupled photoacoustic spectroscopy (GC-PAS) with an essentially monochromatic beam of radiation in an optical portion of the electromagnetic spectrum; the radiation is selected so as to be absorbed by the substance of interest and the beam is modulated at a sonic frequency which is sufficiently high for generating a primary signal that depends upon the absorption coefficient of the substance of interest as well as upon parameters of operating the method; in order to compensate for these operating parameters, the beam is additionally modulated at a sonic frequency which is sufficiently low for generating a secondary signal which does not depend upon the absorption coefficient of the substance of interest, but, depends only upon parameters of operating the method; a ratio of the first and the second signal is obtained to generate a compensated signal for determining the concentration of the substance of interest.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.