Peng Zhimin, Du Yanjun, Ding Yanjun
State Key Laboratory of Power Systems, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
Sensors (Basel). 2020 Jan 26;20(3):681. doi: 10.3390/s20030681.
The absorbance is of great importance in the tunable diode laser absorption spectroscopy (TDLAS) as it contains information of both gas properties and spectroscopic parameters. A novel, calibration-free wavelength modulation-direct absorption spectroscopy (WM-DAS) is proposed and experimentally verified in this two-part paper. This method combines the capability of absorbance measurement from DAS and the advantages of enhanced noise rejection and high sensitivity from WMS. In this , we focus on the full theoretical basis and procedures of this method from the following three aspects: the high-accuracy characterizations of laser frequency and intensity, noise rejection ability by extracting the characteristic spectra through the fast Fourier transform (FFT) of the light intensity, and the simultaneous fitting strategy for both baseline and absorbance. The preliminary validation experiment of CO transition at 4300.6999 cm in a static gas cell shows the high accuracy of the proposed method.
在可调谐二极管激光吸收光谱法（TDLAS）中，吸光度非常重要，因为它包含了气体特性和光谱参数的信息。在这篇分两部分的论文中，提出了一种新型的、无需校准的波长调制直接吸收光谱法（WM-DAS）并进行了实验验证。该方法结合了直接吸收光谱法（DAS）测量吸光度的能力以及波长调制光谱法（WMS）增强的噪声抑制能力和高灵敏度的优点。在此，我们从以下三个方面关注该方法的完整理论基础和步骤：激光频率和强度的高精度表征、通过光强的快速傅里叶变换（FFT）提取特征光谱的噪声抑制能力以及基线和吸光度的同时拟合策略。在静态气室中对4300.6999 cm处的CO跃迁进行的初步验证实验表明了该方法的高精度。
