随着气体参数和分子光谱常数测量精度要求的提高，TDLAS中直接吸收光谱测得的吸收率函数由于信噪比和精度较低越来越难以满足要求。考虑到吸收率函数的重要性（可直接确定气体浓度等参数）和波长调制光谱（灵敏度高、抗干扰能力强）的优点，本项研究拟在扫描波长调制光谱（Scanned-WMS）策略下，充分考虑低频扫描和高频调制耦合作用，基于切比雪夫多项式逼近理论建立一种高精度的吸收率函数复现模型；随后以CO2等分子特征吸收谱线为例，通过数值模拟分析谐波检测精度对所建立模型复现吸收率函数精度的影响，确定不同调制深度下复现吸收率函数需要采用的谐波阶次，并据此建立基于Scanned-WMS的吸收率函数高精度复现方法；最后利用高温炉和激波管模拟多种温度环境对理论研究成果进行实验验证和优化。项目预期可为气体参数高精度测量、分子光谱常数高精度标定以及极端环境下气体参数测量提供新的测量方法，拓展TDLAS的应用范围。

Since the measurement accuracy of gas and spectral line parameters is required to be higher and higher, the tunable diode laser absorption spectroscopy (TDLAS) is hard to satisfy this demand as the absorbance measured by the direct absorption has relatively low signal-to-noise ratio and precision. Considering the importance of absorbance (can be used to infer gas parameters) and the advantage of wavelength modulation spectroscopy (WMS) (highly sensitive and noise resistant), in this project, a high-precision model to recover the absorbance will be built based on the Chebyshev polynomials in the scanned wavelength modulation (Scanned-WMS) scheme. In this model, the coupling effect of the low-frequency scan and high-frequency modulation will be fully addressed. Meanwhile, taking the typical CO2 transition as an example, the influence of the accuracy of harmonic detection on the model and the optimal order of harmonic for different modulation indexes will be discussed through numerical simulations. Then, based on this model, a high-precision measurement method to recover the absorbance will be established with the Scanned-WMS. Finally, the proposed method will be experimentally verified under different temperature conditions produced by a high-temperature tube furnace and a shock tube. The proposed method is expected to extend the application of TDLAS and provide a new measurement method for the high-precision measurements of spectral line parameters and the trace gas sensing in extreme environments.