宽谱调谐二极管激光吸收光谱的数据预处理研究

二极管激光吸收光谱以温度扫描实现快速宽谱调谐,其原始数据不便于传统的处理及运算,适当的预处理是进行后续数据处理的基础。在分析了温度调谐数据特征的基础上,利用Savitzky-Golay滤波器去除了波长序列中温度检测噪声的干扰,选择单调的波长区间对信号幅值进行三次样条插值,以固定的波长点对应采样点,得到一组位置固定的幅值序列用于后期处理。此方法将两列检测数据合并为一列,相同的起始点和固定的波长位置不仅将多周期平均后的信噪比提升为原始数据的6倍,也使多组数据的比较及评价成为可能,一致的波长分辨率保证了线形检测的精确度,减小了吸收峰的频带宽度,有助于后续的处理、运算以及评价。

Data Preprocessing of Broad-Spectrum Tunable-Diode-Laser Absorption Spectroscopy

The diode-laser absorption spectroscopy has been tuned with fast speed and wide wavelength range by temperature scanning. The system original data does not suit for traditional processing and operation, therefore the proper data preprocessing is the basis of the follow-up operation. The original data is processed according to the characteristics of temperature tuning signal. The temperature detection noise in wavelength sequence is removed by Savitzky-Golay filter, then cubic spline interpolation is applied to obtain amplitude sequence with fixed wavelength position for follow-up operation. The result sequence, which has both information of amplitude and wavelength as the same starting point and fixed wavelength position, not only has 6 times higher signal-to-noise ratio than that of original signal by multi periods averaging, but also makes the comparison and evaluation between different signals possible. The consistent wavelength resolution ensures the precision of lineshape detection and decreases the frequency bandwidth of absorption peaks. The experimental results indicate that the data preprocessing provided is beneficial to follow-up operation, calculation and evaluation in such systems.