为了实现二氧化碳气体温度的实时、非接触测量, 研究基于可调谐二极管激光吸收光谱技术(TDLAS)的温度测量方法。根据单激光器的电流调谐特性和谱线对的选择标准, 选取6241.402828 ｃｍ-1、6242.672190 cm-1处的两条对温度有不同依赖关系的二氧化碳谱线进行分析。针对二次谐波幅度法和一、二次谐波幅度比值法所存在的问题, 提出应用一次谐波信号的TDLAS温度测量方案。首先测量两吸收谱线的一次谐波峰峰值和平均值, 以峰峰值和平均值的比值作为单吸收线的输出, 再以两吸收线输出值之比来实现气体温度的测量。实验结果表明: 在200~1000 K范围内, 气体温度测量误差小于30 K。该温度测量方案可消除光强波动对温度测量产生的影响, 且仅需检测一次谐波信号, 系统结构简单, 性能稳定, 可以满足二氧化碳气体温度实时、非接触测量的需要。

For real-time, non-contact measurement of the carbon dioxide temperature, tunable diode laser absorption spectroscopy (TDLAS) temperature measuring method using first harmonic was studied. According to the current tuning characteristics of a single laser and the selection criteria of spectral line pairs, two carbon dioxide lines of 6241.402828 and 6242.672190 cm-1 with different temperature dependence were analyzed. The temperature measurement scheme using TDLAS first harmonic signal was proposed with focus on the existing problems of the second harmonic amplitude method and the first to second harmonic signal amplitude ratio method. First, the first harmonic peak-peak values and the average values of the two absorption lines were measured, and the ratio of the peak-peak value and the average value was used as the system output value of single absorption line. Then after the gas temperature was measured with the ratio of two absorption lines output value.It is experimentally shown that the gas temperature measurement error is less than 30 K in the range of 200~1000 K. The influence of light intensity fluctuation on the temperature measurement can be eliminated by the scheme and stable performance and simple structure are realized, meeting the need of real-time and non-contact temperature measurement of carbon dioxide.