多谱线TDLAS测温中谱线选择的实验研究

Experimental investigation on absorption line selection in temperature measurement from tunable diode laser absorption spectroscopy

采用可调谐半导体激光吸收光谱技术,利用两条谱线可以测量激光路径上的平均温度。在利用多条谱线测量激光路径的平均温度时,测量的精确度主要受制于测量信号的离散程度以及谱线低能级能量的分散程度。利用中心波长为1392.5 nm(7181.32 cm^(-1))的激光器快速扫描4条H_2O的波数为7182.950、7182.209、7181.156、7179.752 cm^(-1)的吸收谱线,研究了不同的谱线组合方式对激光路径平均温度测量精密度的影响。实验结果表明,进行谱线选取时,通过依次去掉一条谱线并计算其余谱线测量标准偏差的结果,能够快速反映出被去掉谱线对温度测量精确度的权重。通过谱线选择,测量得到的路径上平均温度的标准偏差小于20 K。

Using the tunable diode laser absorption spectroscopy （TDLAS） technique, the average temperature along the laser pattt can be measured using two absorption lines. When the average temperature along the laser path is measured by using multiple absorption lines, the measurement accuracy is mainly determined by the deviation of the measured signals and the lower energy of the absorption lines. The laser with a central wavelength of 1 392.5 nm （7 181.32 cm-1 ） can rapidly scan four absorption lines of H20, in which the wave number is 7 182. 950, 7 182. 209, 7 181. 156, and 7 179. 752 cm-1 respectively, and investigate the influence of different combinations of spectral lines on precision of average temperature along laser path. The experimental results show that the weight of the accuracy to the measured temperature of every absorption line can be quickly reflected from calculating the standard deviation of the measured temperature. The standard deviation of the average temperature along the laser path is less than 20 K by absorption line selection.