Lv Shengyujie, Lou Xiaoping, Gai Qiaona, Mu Taotao
School of Instrument Science and Opto-Electronics Engineering, Beijing Information Science and Technology University, Beijing 100192, China.
Sensors (Basel). 2024 Feb 14;24(4):1217. doi: 10.3390/s24041217.
The portable Raman spectrometer boasts portability, rapid analysis, and high flexibility. It stands as a crucial and powerful technical tool for analyzing the chemical composition of samples, whether biological or non-biological, across diverse fields. To improve the resolution of grating spectrometers and ensure a wide spectral range, many spectrometer systems have been designed with double-grating structures. However, the impact of external forces, such as installation deviations and inevitable collisions, may cause differences between the actual state of the internal spectrometer components and their theoretical values. Therefore, spectrometers must be calibrated to establish the relationship between the wavelength and the pixel positions. The characteristic peaks of commonly used calibration substances are primarily distributed in the 200-2000 cm-1 range. The distribution of characteristic peaks in other wavenumber ranges is sparse, especially for spectrometers with double-channel spectral structures and wide spectral ranges. This uneven distribution of spectral peaks generates significant errors in the polynomial fitting results used to calibrate spectrometers. Therefore, to satisfy the calibration requirements of a dual-channel portable Raman spectrometer with a wide spectral range, this study designed a calibration method based on an optical frequency comb, which generates dense and uniform comb-like spectral signals at equal intervals. The method was verified experimentally and compared to the traditional calibration method of using a mercury-argon lamp. The results showed that the error bandwidth of the calibration results of the proposed method was significantly smaller than that of the mercury-argon lamp method, thus demonstrating a substantial improvement in the calibration accuracy.
便携式拉曼光谱仪具有便携性、分析速度快和灵活性高的特点。它是分析各种领域中生物或非生物样品化学成分的关键且强大的技术工具。为了提高光栅光谱仪的分辨率并确保宽光谱范围，许多光谱仪系统采用了双光栅结构进行设计。然而，诸如安装偏差和不可避免的碰撞等外力影响，可能会导致光谱仪内部组件的实际状态与其理论值之间存在差异。因此，必须对光谱仪进行校准，以建立波长与像素位置之间的关系。常用校准物质的特征峰主要分布在200 - 2000 cm-1范围内。在其他波数范围内特征峰的分布较为稀疏，特别是对于具有双通道光谱结构和宽光谱范围的光谱仪。光谱峰的这种不均匀分布会在用于校准光谱仪的多项式拟合结果中产生显著误差。因此，为了满足宽光谱范围双通道便携式拉曼光谱仪的校准要求，本研究设计了一种基于光学频率梳的校准方法，该方法能以等间隔产生密集且均匀的梳状光谱信号。通过实验对该方法进行了验证，并与使用汞氩灯的传统校准方法进行了比较。结果表明，所提方法校准结果的误差带宽明显小于汞氩灯方法，从而证明校准精度有了大幅提高。
