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。

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 on TDLAS 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.