Analysis of relative wavelength response characterization and its effects on scanned-WMS gas sensing  

作　　者：Dao Zheng Zhi-Min Peng Yan-Jun Ding Yan-Jun Du 郑道;彭志敏;丁艳军;杜艳君(State Key Laboratory of Power Systems,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]State Key Laboratory of Power Systems,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China

出　　处：《Chinese Physics B》2021年第4期281-292,共12页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.51906120 and 11972213);China Postdoctoral Science Foundation(Grant Nos.2018M640125 and 2019T120088);the National Basic Research Program of China(Grant No.2016YFC0201104)。

摘　　要：Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly used summation method.A detailed comparison of the three-step method and the summation method,for the wavelength-scanned WMS gas-sensing,was performed with different laser parameters(modulation indexes and scan indexes) and gas properties(pressures and concentrations).Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions.Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method.In addition,the three-step method is further improved by introducing a coupling term for the 2^(nd) harmonic amplitude.Experiments with CO_(2) absorption transition at 6976.2026 cm^(-1) were conducted and validated the simulation analysis.The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method,although the deviation of the deduced CO_(2) concentrations between these two methods does not exceed 0.2%.

关 键 词：tunable diode laser absorption spectroscopy relative wavelength response characterization scanned-wavelength-modulation spectroscopy(WMS) 

分 类 号：O433[机械工程—光学工程] TP212[理学—光学]