Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

Klein, Alexander; Witzel, Oliver; Ebert, Volker

doi:10.3390/s141121497

Cited by 74 publications

(40 citation statements)

References 29 publications

(20 reference statements)

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“…Throughout the paper, 5 ppmv CO signals were used for 2f-WMS calibration. In case a breath test would require a larger dynamic range, rapid time-division multiplexed methods could be used for quasi-simultaneous DAS and WMS detection [31].…”

Section: Sensor Performancementioning

confidence: 99%

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes

Ghorbani¹,

Schmidt²

2017

Opt. Express

102

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We present a compact sensor for carbon monoxide (CO) in air and exhaled breath based on a room temperature interband cascade laser (ICL) operating at 4.69 µm, a lowvolume circular multipass cell and wavelength modulation absorption spectroscopy. A fringelimited (1σ) sensitivity of 6.5 × 10 −8 cm −1 Hz -1/2 and a detection limit of 9 ± 5 ppbv at 0.07 s acquisition time are achieved, which constitutes a 25-fold improvement compared to direct absorption spectroscopy. Integration over 10 s increases the precision to 0.6 ppbv. The setup also allows measuring the stable isotope 13 CO in breath. We demonstrate quantification of indoor air CO and real-time detection of CO expirograms from healthy non-smokers and a healthy smoker before and after smoking. Isotope ratio analysis indicates depletion of 13 CO in breath compared to natural abundance.

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Section: Sensor Performancementioning

confidence: 99%

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes

Ghorbani¹,

Schmidt²

2017

Opt. Express

102

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“…nerate the first harmonic (1f) and second harmonic (2f) absorption signals. 2.2 to maximize the 2f signal 15 . The analyzer compensate for laser wavelength & calibration drifts.…”

Section: Alignment Controlmentioning

confidence: 99%

Optical sensors for harsh environment applications

Sharma

Maity

Bekal

et al. 2015

Sensors for Extreme Harsh Environments II

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The development of a harsh environment ammonia slip sensor based on tunable diode laser absorption spectroscopy is presented. A hybrid optical sensor design, through combination of wavelength modulation spectroscopy (WMS) and alignment control, is proposed as an approach towards reliable in-situ measurements in misalignment prone harsh environments. 1531.59 nm, 1553.4 nm and 1555.56 nm are suggested as possible absorption lines for trace ammonia measurement (<1ppm at 10m path length at 500K) in gas turbine exhaust conditions. Design and performance of the alignment control system are presented in detail. Effect of misalignment related measurement degradation is investigated and significant improvement in measurement fidelity is demonstrated through the use of the hybrid optical sensor design.

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“…To overcome this drawback, incorporating quasi-simultaneous direct absorption measurements alongside the WMS can be considered. This approach was recently demonstrated by Klein et al [27]. Additional background information and a detailed evaluation of the obtained measurement data can be found in Espinoza-Nava et al [28].…”

Section: Field-test At An Alcoa Aluminum Smeltermentioning

confidence: 99%

Continuous Emission Monitoring of Tetrafluoromethane Using Quantum Cascade Lasers

et al. 2016

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Recent developments in quantum cascade lasers have enabled the development of new sensors for in-situ applications that have so far only been possible with extractive systems. In this work, a sensor is presented using a unique Wavelength Modulation Spectroscopy approach to measure tetrafluoromethane, a strong greenhouse gas. The sensor was characterized in a laboratory environment indicating a long-term detection limit of 20 ppb·m and a short-term value of well below 10 ppb·m. To demonstrate the feasibility of the sensor in a real-world environment, it was installed at an Alcoa aluminum smelter. A co-located Fourier Transform Infrared Spectrometer allowed direct comparison measurements of both systems. General agreement between the two methods was observed, leading to the conclusion that the developed in-situ quantum cascade laser based sensor has the potential to continuously measure tetrafluoromethane at aluminum smelters.

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Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

Cited by 74 publications

References 29 publications

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes

ICL-based TDLAS sensor for real-time breath gas analysis of carbon monoxide isotopes

Optical sensors for harsh environment applications

Continuous Emission Monitoring of Tetrafluoromethane Using Quantum Cascade Lasers

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