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基于可调谐半导体激光吸收光谱(TDLAS)技术的传感器系统性能受激光器特性、探测器特性、调制参数、激光器控制电路和信号采集电路等的影响。激光器和探测器特性与当前的生产制造水平密切相关,对于直接吸收法,调制参数主要指扫描幅度和扫描频率,而扫描幅度的确定以得到完整吸收信号为准。对扫描频率的选择和优化进行了详细的讨论。在一定的理论基础上通过实验分别观察各扫描频率对直接吸收信号的影响,通过分析检测信号的特征,如幅值、半峰全宽、调整的判定系数、信噪比、积分吸光度及偏差等得出其变化规律,总结出扫描频率的选择依据。该研究为TDLAS直接吸收法中扫描频率的确定提供了实验依据。
The performance of a sensor system based on tunable semiconductor laser absorption spectroscopy (TDLAS) is affected by the characteristics of the laser, the characteristics of the detector, the modulation parameters, the laser control circuit and the signal acquisition circuit. Laser and detector characteristics are closely related to the current manufacturing level. For the direct absorption method, the modulation parameter mainly refers to the scanning amplitude and the scanning frequency, and the scanning amplitude is determined in order to obtain the complete absorption signal. The selection and optimization of scanning frequency are discussed in detail. On the basis of a certain theory, the effect of each scanning frequency on the direct absorption signal is observed through experiments. By analyzing the characteristics of the detected signal, such as amplitude, full width at half maximum, adjusted judgment coefficient, signal to noise ratio, integral absorbance and deviation Come to its changing law, summed up the choice of scanning frequency basis. This study provides an experimental basis for the determination of scanning frequency in TDLAS direct absorption method.