现代工业生产对气体测量技术的精度、灵敏度、响应速度、稳定性等性能指 标产生了更高的需求，TDLAS 技术可以有效实现对被测气体单一吸收谱线的高 分辨率测量，同时具有成本低、选择性强、响应快、精度高、运行稳定、体积小 等优点，在多领域的生产和研究中逐渐得到广泛应用。本文从吸收光谱的基本原 理出发，围绕直接吸收（DAS）、波长调制（WMS）、扫描-波长调制等测量方法 的研究和应用展开了如下的工作：

    1. 基于吸收光谱理论，分别对 DAS、WMS、2𝑓/1𝑓 等主流方法的测量原理 进行了理论推导，进而延伸出了适用于不同工况的技术思路。其中，直接吸收法 从吸收谱线的线型分布函数出发，给出了积分测量和整条吸收率曲线同步拟合 两种测量方案；波长调制法推导了谐波的通项表达式，并且考虑到激光光强和波 长的非线性响应，根据标定的谐波幅值得到了实用的气体浓度测量方案；在谐波 通项表达式的基础上，推导了 2𝑓/1𝑓 信号的近似线性的通项表达式，实现了气 体浓度的免标定测量。

    2. 为了改善传统波长调制光谱仅测量单项吸收参数的缺陷，采用了使调制 中心进行相对低频的扫描，再进行锁相滤波测量变化的谐波曲线信号的扫描-波 长调制光谱（scan-WMS）。基于吸收信号的频谱分析，对滤波过程的系统误差进 行了深入研究和数值模拟，结果表明调制扫描频率之比𝐾、波长扫描深度𝑠、波 长扫描波形是较为显著的影响因素。

    3. 基于 scan-WMS 的频谱分析，给出了谐波曲线和光谱吸收截面之间的数 值关系，推导了𝑛 次谐波理论模型的精确通项公式，并由此提出了使用单次谐波 曲线𝑅𝑛 计算吸收截面𝛼 的反演方法，实现了利用兼具高灵敏度和信噪比的谐波 曲线同步测量多项吸收气体参数和谱线常数的目标。

    4. 基于 WMS 法中调制信号的谐波分析，开发了使用所有倍频谐波幅值数 据计算完整直接吸收数据，并以波长调制的一倍频信号为中间变量建立激光瞬 时光强信号𝐼 与激光瞬时频率𝜐 之间的关系式，实现多气体参数同步拟合测量的 WM-DAS 方法。基于建立的 WM-DAS 测量和离线处理方案，开发了实用的气体 体积分数在线测量系统，编写了稳定运行的采集和数据处理程序，开发出了实用的在线监测分析仪表，并在磨煤机、锅炉水冷壁等工业应用检测场景中验证了稳 定性。

基于上述方法，本文提出并验证了多种高精度、高灵敏度、抗干扰、多参数 同步测量的气体监测技术，开发了实用化的测量系统，为环保、能源等行业的应 用场景提供了有力的技术支持。

Modern industrial production has produced a higher demand for performance indexes such as precision, sensitivity, response speed and stability of gas measurement technology. TDLAS technology can effectively realize high-resolution measurement of a single absorption spectrum line of measured gas, and has the advantages of low cost, strong selectivity, fast response, high precision, stable operation and small size. It has been widely used in many fields of production and research. Based on the basic principle of absorption spectrum, the research and application of measurement methods such as direct absorption (DAS), wavelength modulation (WMS) and scanning-wavelength modulation are carried out as follows:

1.Based on the absorption spectrum theory, the measurement principles of DAS, WMS, 2𝑓/1𝑓 and other mainstream methods are theoretically derived, and then the technical ideas suitable for different working conditions are extended. Based on the linear distribution function of the absorption spectrum, the direct absorption method presents two measurement schemes: integral measurement and synchronous fitting of the whole absorption curve. The general expression of harmonics is derived by wavelength modulation method, and considering the nonlinear response of laser intensity and wavelength, a practical measurement scheme of gas concentration is obtained according to the calibrated harmonic amplitude. Based on the harmonic general term expression, the approximate linear general term expression of 2𝑓/1𝑓 signal is derived to realize the calibration free measurement of gas concentration.

2.In order to improve the traditional wavelength modulated spectrum which only measures a single absorption parameter, a relatively low frequency scanning is developed for the modulation center, and then phase-locked filtering is used to measure the scan-wavelength modulated spectrum (scan-WMS) of the harmonic curve signal. Based on the Fourier spectrum analysis of the absorbed signal, the systematic errors of the filtering process are studied and simulated. The results show that the ratio of the modulation scanning frequency 𝐾, the wavelength scanning depth 𝑠 and the wavelength scanning waveform are significant factors.

3.Based on the spectrum analysis of scan-WMS, the numerical relationship between the harmonic curve and the spectral absorption cross section is given in the frequency domain of Fourier transform, and the exact general term formula of the theoretical model of the 𝑛th harmonic wave is derived. The inversion method of the absorption cross section 𝛼 is proposed by using the single harmonic curve 𝑅𝑛 . The harmonic curve with high sensitivity and signal-to-noise ratio is used to measure multiple absorption gas parameters and spectral line constants synchronously.

4.Based on WMS method of Fourier spectrum of modulated signal is developed using all times frequency harmonic amplitude data calculate complete absorption data directly, and the one times frequency of wavelength modulation signals for the intermediate variable to establish instantaneous laser intensity and the relation between laser instantaneous 𝐼 and frequency argument 𝜐, I realize the gas parameters of synchronous fitting measurement method of WM - DAS. Based on the established measurement and off-line processing scheme of WM-DAS, a practical on-line measurement system of gas volume fraction is developed, and a stable operation collection and data processing program is written. Then, combining with the constant current dilution gas high fidelity preprocessing technology and distributed multi-point wheel measurement, the developed on-line monitoring and analysis instrument is applied to the industrial site. The on-line monitoring of CO/H2S near the wall of coal mill outlet and pulverized coal boiler water wall is realized.

Based on the above methods, a variety of gas monitoring technologies with high precision, high sensitivity, anti-interference and multi-parameter synchronous measurement are proposed and verified in this paper, and a practical measurement system is developed, which provides strong technical support for the application scenarios of environmental protection and energy industries.