Gas detection technology algorithm based on TDLAS

被引：0

作者：

Jia J. ^{[1
]}

Li W. ^{[1
]}

Chai H. ^{[1
]}

Zhang S. ^{[1
]}

Zhang M. ^{[1
]}

Cui H. ^{[1
]}

Liu J. ^{[1
]}

Liu Z. ^{[1
]}

机构：

[1] Beijing Orient Institute for Measurement and Test, Beijing

来源：

Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | 2019年 / 48卷 / 05期

关键词：

Gas detection; Harmonic signal; Numerical simulation; TDLAS;

D O I：

10.3788/IRLA201948.0517007

中图分类号：

学科分类号：

摘要：

Tunable diode laser absorption spectroscopy (TDLAS) is a high sensitive and high resolution gas absorption spectrum detection technology, with fast response, high precision, excellent single mode characteristics and strong versatility. The temperature and concentration of the detected gas were calculated by measuring the absolute absorption intensity in the direct absorption method of TDLAS, but was easily affected by particle concentration and fluctuation of laser intensity. The laser was modulated through high frequency sinusoidal signal in the wavelength modulation method of TDLAS, making the laser output frequency and intensity modulated simultaneously, with the characteristics of high signal-tonoise ratio and sensitivity, but the gas parameters were determined by calibration experiments or complex algorithms. Therefore, the expression of harmonic terms containing molecular absorption information was deduced through the theory of absorption spectrum and wavelength modulation, and the relationship between harmonic signal and absolute absorption intensity of detected gas was analysed, establishing the measurement algorithm of absolute absorption intensity based on harmonic signal. The absorption spectral line of NH3 molecule near 1 531 nm was taken as an example for numerical analysis, and the relative errors between theoretical calculation (a=0) and simulation values were no more than 2% when the modulation amplitude reached up to a=0.032 cm-1 (m=2), which further proved the reliability of on-line measurement algorithm. © 2019, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.

引用

共 14 条

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