两种红外干涉图采集及光谱复原方法的对比研究

Comparative Study on Two Infrared Interferogram Acquisition and Spectrum Recovery Methods

目前,傅里叶变换红外(FTIR)光谱仪主要的数据采样方法有He-Ne激光触发方法和Brault方法。Brault方法使用硬件计数器而且采集到的数据有延时,会增加数据处理的时间,因此讨论了一种基于Brault方法改进的数据采样与处理方法,该方法采用同步数据采集卡,同时采样两路数据,用近似的相似三角形法得到精确的He-Ne激光过零点信息,然后根据三次样条插值方法重采样干涉信号,实现了软件数据采样与处理。将该方法与He-Ne激光触发方法得到的光谱图进行对比。结果表明,两种方法得到的背景光谱图中H2O和CO2的吸收峰与标准吸收谱带一致,基于Brault方法改进的数据采样与处理方法提高了光谱的信噪比,其激光过零点信息可得到动镜扫描速度的稳定性,而He-Ne激光触发方法的采样与处理时间小于改进的Brault方法。

The primary data sampling methods of Fourier transform infrared （FTIR） spectrometer include He-Ne laser triggering method and Brault method. The Brault method uses the hardware counter and the collected data has time delay, which may lead to the increase of subsequent data processing time. Therefore an improved data sampling and processes method based on the Brault method is proposed. The method adopts the synchronous data acquisition card, and samples two-path data simultaneously, to get the precise zero crossing information of He- Ne laser with approximate similar triangle method. Interference signal is resampled according to the cubic spline interpolation method, and the software data sampling and processing is realized. In addition, the spectra obtained by the He-Ne laser triggering method and the proposed method are compared. The comparison results show that the background of H2O and CO2 absorption peaks in spectra obtained by the two methods are consistent with the standard absorption spectra, the improved data sampling and processing method based on the Brault method improves the signal-to-noise ratio of the spectrum, and the laser zero crossing information can get the stability of the moving mirror scanning speed. However, sampling and processing time for the He-Ne laser triggering method is less than that for the improved Brault method.