Long-path infrared spectrometer
US9097583B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 21, 2013 |
| Grant date | Aug 4, 2015 |
| Priority date | — |
| Expiry date | May 21, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/39
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A tunable mid-infrared laser operated in a pulsed mode is coupled off-axis into a high-finesse optical cavity to produce a long-path spectrometer. The cavity receives a gas sample. Laser pulses may be wavelength-scanned by stepping an external grating, allowing the grating to mechanically settle, then measuring the ring-down with a set of laser pulses, before moving on the next wavelength. A detector receiving infrared light exiting the cavity supplies a cavity ring-down trace representative of sample absorption of the infrared pulses. A processor determines an absolute absorption spectrum of the gas sample from the ring-down trace and analyzes sample gas composition and trace concentration from that spectrum. The absorption baseline is highly reproducible and stable, improving the accuracy of multivariate fits, and the spectral resolution can be better than 0.001 cm−1 (contingent upon the laser source), allowing for high-resolution measurements of sharp absorption features.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.