应用于碳同位素丰度测量的激光频率刻度系统研究

对应用于激光吸收光谱法碳同位素丰度测量中的激光频率实时刻度系统进行研究. 采用不同自由光谱范围的共焦法布里-珀罗干涉仪对测量过程中的激光扫描频率进行实时测量. 分别采用线性内插法和多项式拟合法对激光频率每次扫描过程中的频率非线性进行分析，通过对4976–4980 cm^-1波段CO₂吸收谱的多次测量平均的实验结果与HITRAN-2008数据库相应的吸收峰数据进行比较，得到两种方法的激光频率刻度精度均可达到10^-4 cm^-1，线性内插法的刻度精度要好于多项式拟合法. 验证了激光频率实时刻度系统在碳同位素丰度测量中应用的可行性. 关键词： 激光频率实时刻度 共焦法布里-珀罗干涉仪 同位素丰度测量 激光吸收光谱法

Laser frequency scale system in carbon isotopic abundance measurement

The real-time laser frequency scale system is developed for measuring the carbon isotopic abundance. By using confocal Fabry-Perot interferometer with different free spectral ranges, the diode laser frequency tuning characteristic is acquired in each laser frequency scanning period. During the course of measurements, two nonlinear analysis techniques are tested, i.e., linear interpolation and polynomial fitting. The absorption line center position for CO₂ between 4976 and 4980 cm^-1 is obtained by 100 average measurements from our experiments. A comparison between the measured absorption spectra and the spectral line positions from the HITRAN-2008 database, shows that the two method can both reach an accuracy of 10^-4 cm^-1 for the laser frequency scale. The best results are obtained with a linear interpolation method. The result shows that the laser frequency real-time scale system is applicable in carbon isotopic abundances measurement.
Keywords： real-time laser frequency scale confocal Fabry-Perot interferometer isotopic abundance measurement laser absorption spectroscopy