8 March 2017 Detection of NH3 using logarithmic-transformed wavelength modulation spectroscopy
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Proceedings Volume 10255, Selected Papers of the Chinese Society for Optical Engineering Conferences held October and November 2016; 102552L (2017) https://doi.org/10.1117/12.2263414
Event: Selected Papers of the Chinese Society for Optical Engineering Conferences held October and November 2016, 2016, Jinhua, Suzhou, Chengdu, Xi'an, Wuxi, China
Abstract
Conventional wavelength modulation spectroscopy is improved by logarithmic-transformed data processing for trace gas sensing. Via the logarithmic-transformation, the optic intensity modulation is isolated from the gas absorption induced laser power attenuation, and then the optic intensity modulation is offset by its equivalent which is obtained from a referenced beam. The method is validated by the detection of P(6) NH3-absorption line in a stainless tube with effective path length of 24.5 cm, under room temperature (296 K) and atmospheric pressure (1.01e5 Pa). The second harmonic is recovered while the residual amplitude modulation and distortion of curve are eliminated. A 0.7 ppm (part per million) detection limit is inferred on the assumption that the signal is equal with the noise.
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Menglong Cong, Dandan Sun, Shanshan Zhang, "Detection of NH3 using logarithmic-transformed wavelength modulation spectroscopy", Proc. SPIE 10255, Selected Papers of the Chinese Society for Optical Engineering Conferences held October and November 2016, 102552L (8 March 2017); doi: 10.1117/12.2263414; https://doi.org/10.1117/12.2263414
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