| Zugriffsnummer | 33205 |
| Dokumenttyp | Zeitschriftenartikel |
| Peer Review | mit Peer Review |
| Sprache | Englisch |
| Titel | Rapid, time-division multiplexed, direct absorption- and wavelength modulation-spectroscopy |
| Autor(in); Institution |
Klein, Alexander; 3.2, Gasanalytik und Zustandsverhalten, PTB-Braunschweig
Witzel, Oliver; 3.2, Gasanalytik und Zustandsverhalten, PTB-Braunschweig
Ebert, Volker; 3.2, Gasanalytik und Zustandsverhalten, PTB-Braunschweig
|
| Quelle/Jahr | Sensors: 14 (2014), 21497 - 21513 |
| Availability | [online only] |
| ISSN | 1424-8220 |
| DOI | |
| Verlag | Basel: MDPI |
| Freie Schlagworte | trace gas measurement ; absorption spectroscopy ; TDLAS ; WMS ; hygrometer ; calibration-free |
| Zusammenfassung | We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS) with the enhanced noise rejection of wavelength modulation spectroscopy (WMS). In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS) spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS) and an additional 20 kHz sinusoidal modulation (WMS). The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 µm for H2O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K). A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer. |
| Kostenfreier Zugang | Open Access Gold |
| Rechteinformation | CC BY 4.0 ; Creative Commons Attribution 4.0 License |