Method for calibration-free scanned-wavelength modulation spectroscopy for gas sensing
US9939376B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 2012 |
| Grant date | Apr 10, 2018 |
| Priority date | — |
| Expiry date | Jul 26, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of calibration-free scanned-wavelength modulation spectroscopy (WMS) absorption sensing is provided by obtaining absorption lineshape measurements of a gas sample on a sensor using 1f-normalized WMS-2f where an injection current to an injection current-tunable diode laser (TDL) is modulated at a frequency f, where a wavelength modulation and an intensity modulation of the TDL are simultaneously generated, extracting using a numerical lock-in program and a low-pass filter appropriate band-width WMS-nf (n=1, 2, . . . ) signals, where the WMS-nf signals are harmonics of the f, determining a physical property of the gas sample according to ratios of the WMS-nf signals, determining the zero-absorption background using scanned-wavelength WMS, and determining non-absorption losses using at least two of the harmonics, where a need for a non-absorption baseline measurement is removed from measurements in environments where collision broadening has blended transition linewidths, where calibration free WMS measurements without knowledge of the transition linewidth is enabled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.