Gas detection method and gas detection device
US7183553B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 2005 |
| Grant date | Feb 27, 2007 |
| Priority date | — |
| Expiry date | Oct 8, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/0691
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The gas detector device comprises at least a VCSEL source and at least a light sensor for detecting a light beam having passed through a sample chamber containing a given gas to be detected. The detection signal of the sensor directly provided to or is time derivated by an electronic derivator and then provided to respective lock-in amplifiers in order to generate a two different 2f-detection, f being the frequency of a wavelength modulation of the source, and thus to provide two corresponding measuring signals the division of which gives a precise value of the gas concentration. The invention uses at least a first modulation reference signal at twice and a second modulation reference signal at twice of the modulation frequency of the laser source. Providing at least a first 2f modulation reference signal has advantages over the prior art, because by using such a reference modulation signal it is possible measure the absolute intensity and therefore to receive the same result at different temperatures or at mode hopping of the laser. A further advantage is that the measurement accuracy is independent from the gas concentration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.