Handheld, battery-powered near-IR TDL sensor for stand-off detection of gas and vapor plumes

Wainner, Richard T.; Green, B.D.; Allen, Mark G.; Frish, Michael B.; White, Michael A.; Stafford-Evans, J.

doi:10.1007/s00340-002-0984-7

Cited by 71 publications

(31 citation statements)

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“…Wavelength modulation spectroscopy (WMS) has high sensitivity and signal-to-noise ratio (SNR) to determine the gas parameters [9][10][11][12][13]. In WMS, line width is necessary to calculate the harmonics whether you use the 2nd harmonic detection or the ''calibration-free 2f/1f'' method [14][15][16][17]. As mentioned above, line widths are also determined by gas parameters.…”

Section: Introductionmentioning

confidence: 98%

Calibration-free wavelength modulation for gas sensing in tunable diode laser absorption spectroscopy

et al. 2014

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A method is proposed that employs the ratios of the 2nd and 4th harmonics at the line center to measure line width under high absorption. The measured line width is then applied in the ''calibration-free 2f/1f'' formula to detect gas pressure and concentration. To verify this method, the transitions of CO 2 at 6,982.0678 cm -1 and H 2 O at 6,979.2995 cm -1 are selected to measure the line width, gas pressure, and concentration in laboratory and field environments, respectively. Experimental results are very consistent with the expectations.

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Section: Introductionmentioning

confidence: 98%

Calibration-free wavelength modulation for gas sensing in tunable diode laser absorption spectroscopy

et al. 2014

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“…Attempts have been made to further shorten the wavelength for this application by using blue/green semiconductor lasers. Semiconductor lasers lasing at wavelengths ranging from visible to infrared are increasingly being used in sensing equipment for combustion-gas sensing and greenhouse-gases, medical equipment, and IT-agriculture fields [5][6][7][8][9]. Some examples of these applications are shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Reliability of semiconductor lasers used in current communication systems and sensing equipment

Fukuda

2007

Microelectronics Reliability

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“…Harmonic detection was reported for the first time 1982 by Cassidy [9] and subsequently has been widely used. [10,11] Harmonic detection separates the useful signal from background noise and improves the signal-tonoise ratio and sensitivity and also uses modulation and demodulation to reduce random noise. This approach has achieved high sensitivity for methane, carbon monoxide, carbon dioxide, and other gases.…”

Section: Introductionmentioning

confidence: 99%

Novel Gas Concentration Measurements based on Harmonic Detection and a Broadband Light Source

Wang

Kong

et al. 2014

Instrumentation Science & Technology

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& The determination of gas concentration based on harmonic detection was studied theoretically and experimentally. The principle of second harmonic detection technology based on a broadband light source and the impact of modulation parameters on the harmonic signals were analyzed theoretically. The principles of multiple modulation were analyzed in order to improve the detection resolution. A fiber Bragg grating bonded to a carbon fiber cantilever was designed to achieve wavelength modulation. The impact of the modulation frequency and voltage amplitude on the second harmonic signals were studied experimentally. The output of the detector and the impact of the random noise were analyzed at different modulation frequencies and amplitudes. The optimum frequency and amplitude were determined to be 40 Hz and 2 V. The measurement of acetylene was carried out using this system. The results show that the gas measurement limit was 500 ppm, the stability was 3.92%, and the system sensitivity was 1 mV=ppm.

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Handheld, battery-powered near-IR TDL sensor for stand-off detection of gas and vapor plumes

Cited by 71 publications

References 0 publications

Calibration-free wavelength modulation for gas sensing in tunable diode laser absorption spectroscopy

Calibration-free wavelength modulation for gas sensing in tunable diode laser absorption spectroscopy

Reliability of semiconductor lasers used in current communication systems and sensing equipment

Novel Gas Concentration Measurements based on Harmonic Detection and a Broadband Light Source

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