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提出了一种利用TDLAS吸收光谱技术,通过测量一氧化碳吸收谱线的二次谐波和四次谐波的最大值,从而准确计算出一氧化碳浓度的新方法。这种方法的的特点在于,测量结果与激光器的调制强度无关。并且,测量的相对误差与半导体激光器的调制电流所引起的频率变化量的差异没有关系。结果表明,这种利用在吸收谱线上的特殊频点上的二次谐波和四次谐波的相对强度来计算气体浓度的方法,能够高效、实时和高精度地测量一氧化碳气体浓度。
A new method for accurately calculating the concentration of carbon monoxide by TDLAS absorption spectroscopy was proposed by measuring the maximum of the second harmonic and the fourth harmonic of the absorption line of carbon monoxide. The characteristic of this method is that the measurement results are independent of the intensity of the laser modulation. Also, the relative error of the measurement does not depend on the difference in the frequency variation caused by the modulation current of the semiconductor laser. The results show that this method of calculating the concentration of gas using the relative intensities of the second and fourth harmonics at specific frequencies on the absorption line enables the measurement of the concentration of carbon monoxide gas efficiently, in real time and with high accuracy.