用于激光吸收光谱二维重建的光谱优化选择方法研究

Method of Optimal Spectral Lines Selection for Two-Dimensional Reconstruction of Laser Absorption Spectroscopy

关键词:  激光吸收光谱  多光谱重建  线性相关指数  光谱选择  光谱数量

Key words:  Laser absorption spectroscopy  Multi-spectral absorption tomography  Linear correlation index  Spectral line selection  Spectral line number

摘要:

光谱组合对多光谱重建技术的重建结果有很大影响，不合理的光谱组合会降低光谱测量的有效性，加大重建误差。为了从海量的光谱数据库中选出适用于被测流场参数范围的最优光谱组合，提出了一种基于向量组线性相关性的光谱选择方法，采用数值仿真的方法开展研究，仿真结果验证了方法的可行性与可靠性。分析了测量信号无噪声和存在噪声时，光谱数量与重建结果的关系。研究发现最优光谱组合的线性相关指数小于0.01时，该组合存在光谱的冗余。保证测量有效性的同时光谱数量最少的光谱组合为线性相关指数不小于0.01的最优光谱组合。测量存在噪声时，光谱数量越多，噪声的抑制效果越好，重建结果精度更高。通过重复测量法可以有效降低噪声影响，用最少数量的光谱实现更多光谱的测量效果。

Abstract:

Spectral line combination has a great influence on the reconstruction result of multi-spectral laser absorption tomography. Poor spectral combination reduces the effectiveness of spectrum measurement and increases reconstruction error. In order to select the optimal spectrum combination suitable for the target flow field parameter range from the massive spectrum database， this paper proposes a spectrum selection method based on the linear correlation of the vector group. Numerical simulations verify the feasibility and reliability of the method. The relationship between the number of spectra and the reconstruction results is analyzed when the measured signal is noise-free and noisy. It is found that when the linear correlation index （LCI） of the optimal spectral combination is less than 0.01， the combination has spectral redundancy. The line combination with the least number of spectra while ensuring the validity of the measurement is the optimal spectrum combination with an LCI not less than 0.01. When there is noise in the measurement， the more the number of spectra lines， the better the noise suppression effect， and the higher the accuracy of the reconstruction result. The repeated measurement method can effectively reduce the effect of noise and use the least number of spectra to achieve more spectral measurement effects.