基于可调谐半导体激光吸收光谱的氧气测量方法的研究

O2是工业过程中广泛应用的重要气体,在工业生产环境下实现O2浓度的快速在线检测对提高燃烧效率和节能减排具有重要的意义.可调谐半导体激光吸收光谱谐波探测技术是一种具有高灵敏、高选择性、快速响应等特点的气体检测新技术,该技术利用了半导体激光器的可调谐和窄线宽特性,通过精心选择待测气体的某条吸收线可排除其他气体的干扰,实现待测气体浓度的高灵敏快速在线检测.文章以可调谐分布反馈(Distributed feedback,DFB)半导体激光器作为光源,通过波长调制方法对760 nm附近氧气某一吸收线的二次谐波信号测量,从而实现了对氧气浓度的快速在线检测.系统指标达到:检测范围0.01%～20%;检测精度0.1%;长期稳定性1%.

Monitoring of Oxygen Concentration Based on Tunable Diode Laser Absorption Spectroscopy

Oxygen is a widely used important gas in the industrial process. It is very meaningful to on-line monitor the oxygen concentration for the enhancement of combustion efficiency and reduction in environmental pollution. Tunable diode laser absorption spectroscopy (TDLAS) is a highly sensitive, highly selective and fast time response trace gas detection technique. With the features of tunability and narrow linewidth of distributed feedback (DFB) diode laser and by precisely tuning the laser output wavelength to a single isolated absorption line of the gas, TDLAS technique can be utilized to accurately implement gas concentration measurement with very high sensitivity. In the present paper, the authors used a DFB laser was used as the light source, and by employing wavelength modulation method and measuring the second harmonic signal of one absorption line near 760 nm of oxygen molecule, the authors built a system for online monitoring of oxygen concentration. The characteristics of the system are as follows： the scope of detection is 0.01%-20% ; detection accuracy is 0.1 %, long term stability is 1 %.