基于激光吸收光谱技术的CO_2痕量检测及调制参数的优化

采用可调谐激光吸收光谱技术,在室温下对中心波长为2004nm的分布反馈式半导体激光器进行波长调制,可得到CO_2在2004nm处的二次谐波幅值,根据Beer-Lambert定律,计算出CO_2的浓度。正弦调制参数是影响系统检测灵敏度和精度的重要因素,通过对正弦调制信号频率、幅值与二次谐波线型之间关系的研究,实现了每米光程下10ppm的检测下限。

Measurement of Concentration of Carbon Dioxide Gas with TDLAS and Modulation Parameters Optimization

Based on the technology of tunable laser absorption spectroscopy,modulation the center wavelength of 2004 nm distributed feedback semiconductor laser at a room-temperature,the second harmonic amplitude at 2004nm of CO2 can be obtained. The CO2 concentration can be calculated via the Beer-Lambert law. Sinusoidal modulation parameter is a important factor that affect the sensitivity and accuracy of the system,through the research about the relationship between sinusoidal modulation signal frequency,amplitude and line of the second harmonic,we finally achieved the de-tection limit of 5ppm under 12 m optical path.