Wang Xianli, Hu Chuanzhen, Chu Kaiqin, Smith Zachary J
Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, Anhui, China.
Analyst. 2020 Oct 21;145(20):6607-6616. doi: 10.1039/d0an01390k. Epub 2020 Aug 13.
The majority of problems in analytical Raman spectroscopy are mathematically over-determined, where many more spectral variables are measured than analytic outputs (such as chemical concentrations) are calculated. Thus, to improve spectral throughput and simplify system design, some researchers have explored the use of low resolution Raman systems for cell or tissue classification, achieving accuracy independent of spectral resolution. However, the tradeoffs inherent in this approach have not been systematically studied. Here, we theoretically and experimentally explore the relationship between spectral resolution and analytical error. We show that decreased spectral resolution leads to spectral signal-to-noise ratio and therefore more reliable results and lower limits of detection for equivalent integration times in blind unmixing of hyperspectral images. Our theoretical analysis demonstrates that the primary benefit of low resolution Raman spectroscopy is in overcoming detector noise (such as thermal or electronic noise). Therefore, the benefits are most pronounced when utilizing lower-grade, uncooled detectors. Therefore, using a low-cost CMOS camera we experimentally demonstrate the ability of low resolution Raman spectroscopy to achieve substantially improved imaging performance compared to fully-resolved Raman spectral imaging, paving the way for cost-effective, pervasive Raman spectroscopy.
分析拉曼光谱中的大多数问题在数学上是超定的，即测量的光谱变量比计算的分析输出（如化学浓度）多得多。因此，为了提高光谱通量并简化系统设计，一些研究人员探索了使用低分辨率拉曼系统进行细胞或组织分类，实现了与光谱分辨率无关的准确性。然而，这种方法固有的权衡尚未得到系统研究。在这里，我们从理论和实验上探索光谱分辨率与分析误差之间的关系。我们表明，降低光谱分辨率会导致光谱信噪比提高，从而在高光谱图像的盲解混中，对于等效积分时间能得到更可靠的结果和更低的检测限。我们的理论分析表明，低分辨率拉曼光谱的主要优势在于克服探测器噪声（如热噪声或电子噪声）。因此，在使用较低等级的非制冷探测器时，这种优势最为明显。因此，我们使用低成本的互补金属氧化物半导体（CMOS）相机通过实验证明，与全分辨率拉曼光谱成像相比，低分辨率拉曼光谱能够显著提高成像性能，为经济高效、广泛应用的拉曼光谱铺平了道路。
