Results 151 to 160 of about 825 (180)
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QEPAS sensor for breath analysis: a behavior of pressure
Applied Optics, 2018The measurement of trace gases has increasingly become a key technique in healthcare and other medical applications. Quartz-enhanced photoacoustic spectroscopy (QEPAS) is a suitable method that can provide the required characteristics in such applications for a comparatively low cost and small size.
Tobias Milde +7 more
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QEPAS spectrophones: design, optimization, and performance
Applied Physics B, 2010The impact of design parameters of a spectrophone for quartz-enhanced photoacoustic spectroscopy on its performance was investigated. The microresonator of spectrophone is optimized based on an experimental study. The results show that a 4.4 mm-long tube with 0.6 mm inner diameter yields the highest signal-to-noise ratio, which is ∼30 times higher than
L. Dong +3 more
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Miniaturized QEPAS Detector Concept for Methane
Conference on Lasers and Electro-Optics, 2020QEPAS enables very compact detectors due to the small detection volume. Currently limitations originate from bulky control electronics, like lock-in amplifiers. We report on reducing size and energy of FPGA based devices and their application in methane detection.
Hervé Tatenguem +4 more
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Modeling and Design of a Semi-Integrated QEPAS Sensor
Journal of Lightwave Technology, 2021Quartz enhanced photo acoustic spectroscopy (QEPAS) has gained a growing interest in recent years for gas sensing technology because of the high sensitivity provided by sharp resonant tuning forks (QTFs) exploited as piezoelectric sound wave detectors; and the modularity, compactness, and robustness of the sensors.
Martino De Carlo +5 more
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QEPAS detector for rapid spectral measurements
Applied Physics B, 2010A quartz enhanced photoacoustic spectroscopy sensor designed for fast response was used in combina- tion with a pulsed external cavity quantum cascade laser to rapidly acquire gas absorption data over the 1196- 1281 cm −1 spectral range. The system was used to measure concentrations of water vapor, pentafluoroethane (freon- 125), acetone, and ethanol ...
A. A. Kosterev +5 more
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A Novel QEPAS with Microresonator in the Open Environment
International Journal of Thermophysics, 2012An improved quartz-enhanced photoacoustic spectroscopy (QEPAS) sensing system for trace gas detection is proposed. The optical fiber Fabry–Perot (F–P) demodulation method is used to replace the conventional electrical one in the QEPAS system. The experimental QEPAS system, which has a microresonator consisting of two stainless steel tubes with a length
Cheng Lin +4 more
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Acetylene-enhanced methane-QEPAS sensing
Optics LettersMethane (CH4), as a critical greenhouse gas and explosive hazard, demands highly sensitive detection for environmental monitoring and industrial safety. To address the limitation of its slow relaxation in quartz-enhanced photoacoustic spectroscopy (QEPAS), this paper reported a novel acetylene (C2H2)-enhanced QEPAS technique for CH4 sensing for the ...
Jin Sun +4 more
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Compact portable QEPAS multi-gas sensor
SPIE Proceedings, 2011A quartz-enhanced photoacoustic spectroscopy (QEPAS) based multi-gas sensor was developed to quantify concentrations of carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen chloride (HCl), and carbon dioxide (CO2) in ambient air. The sensor consists of a compact package of dimensions 25cm x 25cm x 10cm and was designed to operate at atmospheric ...
Lei Dong +3 more
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QEPAS methane sensor performance for humidified gases
Applied Physics B, 2008A trace gas sensor based on quartz enhanced photoacoustic spectroscopy (QEPAS) was evaluated using humidified nitrogen samples and ambient air. Relaxation processes following vibrational excitation of 2ν3 state of CH4 were investigated. Sensor performance at different gas pressures could be predicted based on a developed kinetic model.
A.A. Kosterev +4 more
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A QEPAS sensor with a ~1.37 μm DFB laser
Asia Communications and Photonics Conference 2013, 2013We demonstrate a QEPAS sensor using a ~1.37μm DFB laser as light source and a quartz tuning fork as a transducer to detect water vapor concentration in the air.
Ping Gong +3 more
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