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230031 2 合肥工业大学仪器科学与光电工程学院, 安徽 合肥 230009 摘要 采用可调谐半导体激光吸收光谱(TDLAS)技术， 利用氧气在 760 nm 波段的吸收谱线对氧气浓度进行实时在线 测量。研制了基于 TDLAS 直接吸收技术的氧气检测系统， 采用压控放大器设计了自动增益控制模块， 实现了对光谱 信号幅度的精确控制， 解决了现场测量中信号幅度波动的问题； 采用归一化洛伦兹函数实现 Voigt 函数的近似计算， 并 结合 Levenberg-Marquardt 非线性拟合算法实现了对光谱吸光度曲线的快速 Voigt 线型拟合， 以适应实时在线检测需要。 实验结果表明， 该算法可以实现吸光度曲线的 Voigt 线型拟合， 对固定浓度的氧气进行连续测量得到系统的最低检测 限为 523×10 -6 m， 系统的标准偏差为 1.75%。检测系统稳定可靠， 满足实时在线氧气浓度检测应用。 关键词 光谱学; 可调谐半导体激光吸收光谱; 自动增益控制; Levenberg-Marquardt 非线性拟合; 氧气浓度测量 中图分类号 O657.3 文献标识码 A Abstract The tunable diode laser absorption spectroscopy (TDLAS) technology and oxygen absorption lines near 760 nm are used to realize real-time on-line measurement of oxygen concentration. A detection system based onTDLAS direct absorption technique is designed. In order to solve signal amplitude fluctuation for on-site measurement, an automatic gain control module is designed using voltage controlled amplifier to achieve precise control of the spectrum signal amplitude; generalized Lorentz function is adopted to realize the approximate calculation of Voigt function combining Levenberg-Marquardt nonlinear fitting method to realize fast Voigt profile fitting of the absorbance spectrum curve, to meet the requirement of real-time on-line detection. Experimental results show that the algorithm can achieve Voigt profile fitting of absorbance curve. A fixed concentration of oxygen is continuously measured. Minimum detection limit of the system is 523 × 10 -6 m, and standard deviation is 1.75%.Detection system is reliable and meets the real-time on-line oxygen concentration detection applications.

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